Bump ApiSurface from 4.0.36 to 4.0.39 (#132)

* Bump ApiSurface from 4.0.36 to 4.0.39

Bumps [ApiSurface](https://github.com/G-Research/ApiSurface) from 4.0.36 to 4.0.39.
- [Release notes](https://github.com/G-Research/ApiSurface/releases)
- [Commits](https://github.com/G-Research/ApiSurface/compare/ApiSurface.4.0.36...ApiSurface.4.0.39)

---
updated-dependencies:
- dependency-name: ApiSurface
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

* Bump deps

---------

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Smaug123 <3138005+Smaug123@users.noreply.github.com>

.config/dotnet-tools.json

@@ -3,13 +3,13 @@
   "isRoot": true,
   "tools": {
     "fantomas": {
-      "version": "6.3.0-alpha-005",
+      "version": "6.3.4",
       "commands": [
         "fantomas"
       ]
     },
     "fsharp-analyzers": {
-      "version": "0.23.0",
+      "version": "0.25.0",
       "commands": [
         "fsharp-analyzers"
       ]

.editorconfig

@@ -2,7 +2,6 @@ root=true
 
 [*]
 charset=utf-8
-end_of_line=crlf
 trim_trailing_whitespace=true
 insert_final_newline=true
 indent_style=space

.gitattributes

@@ -1,5 +1,5 @@
-* eol=auto
-*.sh text eol=lf
-*.yaml text
-*.nix text eol=lf
-hooks/pre-push text eol=lf
+* eol=auto
+*.sh text eol=lf
+*.yaml text
+*.nix text eol=lf
+hooks/pre-push text eol=lf

.github/workflows/dotnet.yaml

@@ -28,7 +28,7 @@ jobs:
       with:
         fetch-depth: 0 # so that NerdBank.GitVersioning has access to history
     - name: Install Nix
-      uses: cachix/install-nix-action@v25
+      uses: cachix/install-nix-action@v26
       with:
         extra_nix_config: |
           access-tokens = github.com=${{ secrets.GITHUB_TOKEN }}
@@ -49,7 +49,7 @@ jobs:
         with:
           fetch-depth: 0 # so that NerdBank.GitVersioning has access to history
       - name: Install Nix
-        uses: cachix/install-nix-action@v25
+        uses: cachix/install-nix-action@v26
         with:
           extra_nix_config: |
             access-tokens = github.com=${{ secrets.GITHUB_TOKEN }}
@@ -58,7 +58,7 @@ jobs:
       - name: Build project
         run: nix develop --command dotnet build ./WoofWare.Myriad.Plugins/WoofWare.Myriad.Plugins.fsproj
       - name: Run analyzers
-        run: nix run .#fsharp-analyzers -- --project ./WoofWare.Myriad.Plugins/WoofWare.Myriad.Plugins.fsproj --analyzers-path ./.analyzerpackages/g-research.fsharp.analyzers/0.6.0/ --verbosity detailed --report ./analysis.sarif --treat-as-error GRA-STRING-001 GRA-STRING-002 GRA-STRING-003 GRA-UNIONCASE-001 GRA-INTERPOLATED-001 GRA-TYPE-ANNOTATE-001 GRA-VIRTUALCALL-001 GRA-IMMUTABLECOLLECTIONEQUALITY-001 GRA-JSONOPTS-001 GRA-LOGARGFUNCFULLAPP-001
+        run: nix run .#fsharp-analyzers -- --project ./WoofWare.Myriad.Plugins/WoofWare.Myriad.Plugins.fsproj --analyzers-path ./.analyzerpackages/g-research.fsharp.analyzers/*/ --verbosity detailed --report ./analysis.sarif --treat-as-error GRA-STRING-001 GRA-STRING-002 GRA-STRING-003 GRA-UNIONCASE-001 GRA-INTERPOLATED-001 GRA-TYPE-ANNOTATE-001 GRA-VIRTUALCALL-001 GRA-IMMUTABLECOLLECTIONEQUALITY-001 GRA-JSONOPTS-001 GRA-LOGARGFUNCFULLAPP-001 GRA-DISPBEFOREASYNC-001 --exclude-analyzers PartialAppAnalyzer
 
   build-nix:
     runs-on: ubuntu-latest
@@ -66,7 +66,7 @@ jobs:
       - name: Checkout
         uses: actions/checkout@v4
       - name: Install Nix
-        uses: cachix/install-nix-action@v25
+        uses: cachix/install-nix-action@v26
         with:
           extra_nix_config: |
             access-tokens = github.com=${{ secrets.GITHUB_TOKEN }}
@@ -79,7 +79,7 @@ jobs:
       - name: Checkout
         uses: actions/checkout@v4
       - name: Install Nix
-        uses: cachix/install-nix-action@v25
+        uses: cachix/install-nix-action@v26
         with:
           extra_nix_config: |
             access-tokens = github.com=${{ secrets.GITHUB_TOKEN }}
@@ -92,7 +92,7 @@ jobs:
       - name: Checkout
         uses: actions/checkout@v4
       - name: Install Nix
-        uses: cachix/install-nix-action@v25
+        uses: cachix/install-nix-action@v26
         with:
           extra_nix_config: |
             access-tokens = github.com=${{ secrets.GITHUB_TOKEN }}
@@ -105,7 +105,7 @@ jobs:
     steps:
       - uses: actions/checkout@master
       - name: Install Nix
-        uses: cachix/install-nix-action@v25
+        uses: cachix/install-nix-action@v26
         with:
           extra_nix_config: |
             access-tokens = github.com=${{ secrets.GITHUB_TOKEN }}
@@ -118,7 +118,7 @@ jobs:
     steps:
       - uses: actions/checkout@master
       - name: Install Nix
-        uses: cachix/install-nix-action@v25
+        uses: cachix/install-nix-action@v26
         with:
           extra_nix_config: |
             access-tokens = github.com=${{ secrets.GITHUB_TOKEN }}
@@ -132,7 +132,7 @@ jobs:
       with:
         fetch-depth: 0 # so that NerdBank.GitVersioning has access to history
     - name: Install Nix
-      uses: cachix/install-nix-action@v25
+      uses: cachix/install-nix-action@v26
       with:
         extra_nix_config: |
           access-tokens = github.com=${{ secrets.GITHUB_TOKEN }}
@@ -142,23 +142,37 @@ jobs:
       run: nix develop --command dotnet build --no-restore --configuration Release
     - name: Pack
       run: nix develop --command dotnet pack --configuration Release
-    - name: Upload NuGet artifact
+    - name: Upload NuGet artifact (plugin)
       uses: actions/upload-artifact@v4
       with:
-        name: nuget-package
+        name: nuget-package-plugin
         path: WoofWare.Myriad.Plugins/bin/Release/WoofWare.Myriad.Plugins.*.nupkg
+    - name: Upload NuGet artifact (attributes)
+      uses: actions/upload-artifact@v4
+      with:
+        name: nuget-package-attribute
+        path: WoofWare.Myriad.Plugins.Attributes/bin/Release/WoofWare.Myriad.Plugins.Attributes.*.nupkg
 
   expected-pack:
     needs: [nuget-pack]
     runs-on: ubuntu-latest
     steps:
-      - name: Download NuGet artifact
+      - name: Download NuGet artifact (plugin)
         uses: actions/download-artifact@v4
         with:
-          name: nuget-package
+          name: nuget-package-plugin
+          path: packed-plugin
       - name: Check NuGet contents
         # Verify that there is exactly one nupkg in the artifact that would be NuGet published
-        run: if [[ $(find . -maxdepth 1 -name 'WoofWare.Myriad.Plugins.*.nupkg' -printf c | wc -c) -ne "1" ]]; then exit 1; fi
+        run: if [[ $(find packed-plugin -maxdepth 1 -name 'WoofWare.Myriad.Plugins.*.nupkg' -printf c | wc -c) -ne "1" ]]; then exit 1; fi
+      - name: Download NuGet artifact (attributes)
+        uses: actions/download-artifact@v4
+        with:
+          name: nuget-package-attribute
+          path: packed-attribute
+      - name: Check NuGet contents
+        # Verify that there is exactly one nupkg in the artifact that would be NuGet published
+        run: if [[ $(find packed-attribute -maxdepth 1 -name 'WoofWare.Myriad.Plugins.Attributes.*.nupkg' -printf c | wc -c) -ne "1" ]]; then exit 1; fi
 
   all-required-checks-complete:
     needs: [check-dotnet-format, check-nix-format, build, build-nix, linkcheck, flake-check, analyzers, nuget-pack, expected-pack]
@@ -174,13 +188,43 @@ jobs:
     steps:
       - uses: actions/checkout@v4
       - name: Install Nix
-        uses: cachix/install-nix-action@v25
+        uses: cachix/install-nix-action@v26
         with:
           extra_nix_config: |
             access-tokens = github.com=${{ secrets.GITHUB_TOKEN }}
-      - name: Download NuGet artifact
+      - name: Download NuGet artifact (plugin)
         uses: actions/download-artifact@v4
         with:
-          name: nuget-package
-      - name: Publish to NuGet
-        run: nix develop --command dotnet nuget push "WoofWare.Myriad.Plugins.*.nupkg" --api-key ${{ secrets.NUGET_API_KEY }} --source https://api.nuget.org/v3/index.json
+          name: nuget-package-plugin
+          path: packed-plugin
+      - name: Publish to NuGet (plugin)
+        run: nix develop --command dotnet nuget push "packed-plugin/WoofWare.Myriad.Plugins.*.nupkg" --api-key ${{ secrets.NUGET_API_KEY }} --source https://api.nuget.org/v3/index.json --skip-duplicate
+      - name: Download NuGet artifact (attribute)
+        uses: actions/download-artifact@v4
+        with:
+          name: nuget-package-attribute
+          path: packed-attribute
+      - name: Publish to NuGet (attribute)
+        run: nix develop --command dotnet nuget push "packed-attribute/WoofWare.Myriad.Plugins.Attributes.*.nupkg" --api-key ${{ secrets.NUGET_API_KEY }} --source https://api.nuget.org/v3/index.json --skip-duplicate
+
+  github-release-plugin:
+    runs-on: ubuntu-latest
+    if: ${{ !github.event.repository.fork && github.ref == 'refs/heads/main' }}
+    needs: [all-required-checks-complete]
+    environment: main-deploy
+    permissions:
+      contents: write
+    steps:
+      - uses: actions/checkout@v4
+      - name: Download NuGet artifact (plugin)
+        uses: actions/download-artifact@v4
+        with:
+          name: nuget-package-plugin
+      - name: Download NuGet artifact (attribute)
+        uses: actions/download-artifact@v4
+        with:
+          name: nuget-package-attribute
+      - name: Tag and release plugin
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: sh .github/workflows/tag.sh

.github/workflows/tag.sh

@@ -0,0 +1,17 @@
+#!/bin/sh
+
+find . -maxdepth 1 -type f -name '*.nupkg' -exec sh -c 'tag=$(basename "$1" .nupkg); git tag "$tag"; git push origin "$tag"' shell {} \;
+
+export TAG
+TAG=$(find . -maxdepth 1 -type f -name 'WoofWare.Myriad.Plugins.*.nupkg' -exec sh -c 'basename "$1" .nupkg' shell {} \; | grep -v Attributes)
+
+case "$TAG" in
+  *"
+"*)
+    echo "Error: TAG contains a newline; multiple plugins found."
+    exit 1
+    ;;
+esac
+
+# target_commitish empty indicates the repo default branch
+curl -L -X POST -H "Accept: application/vnd.github+json" -H "Authorization: Bearer $GITHUB_TOKEN" -H "X-GitHub-Api-Version: 2022-11-28" https://api.github.com/repos/Smaug123/WoofWare.Myriad/releases -d '{"tag_name":"'"$TAG"'","target_commitish":"","name":"'"$TAG"'","draft":false,"prerelease":false,"generate_release_notes":false}'

CHANGELOG.md

@@ -0,0 +1,6 @@
+Notable changes are recorded here.
+
+# WoofWare.Myriad.Plugins 1.4 -> 2.0
+
+This transition split the attributes (e.g. `[<JsonParseAttribute>]`) into their own assembly, WoofWare.Myriad.Plugins.Attributes.
+The new assembly has minimal dependencies, so you may safely use it from your own code.

ConsumePlugin/Catamorphism.fs

@@ -0,0 +1,22 @@
+namespace ConsumePlugin
+
+open WoofWare.Myriad.Plugins
+
+type Const<'a> =
+    | Verbatim of 'a
+    | String of string
+
+type PairOpKind =
+    | NormalSeq
+    | ThenDoSeq
+
+[<CreateCatamorphism "TreeCata">]
+type Tree<'a, 'b> =
+    | Const of Const<'a> * 'b
+    | Pair of Tree<'a, 'b> * Tree<'a, 'b> * PairOpKind
+    | Sequential of Tree<'a, 'b> list
+    | Builder of Tree<'a, 'b> * TreeBuilder<'b, 'a>
+
+and TreeBuilder<'b, 'a> =
+    | Child of TreeBuilder<'b, 'a>
+    | Parent of Tree<'a, 'b>

ConsumePlugin/ConsumePlugin.fsproj

@@ -39,10 +39,23 @@
     <Compile Include="GeneratedSerde.fs">
       <MyriadFile>SerializationAndDeserialization.fs</MyriadFile>
     </Compile>
+    <Compile Include="Catamorphism.fs" />
+    <Compile Include="GeneratedCatamorphism.fs">
+      <MyriadFile>Catamorphism.fs</MyriadFile>
+    </Compile>
+    <Compile Include="FSharpForFunAndProfitCata.fs" />
+    <Compile Include="GeneratedFileSystem.fs">
+      <MyriadFile>FSharpForFunAndProfitCata.fs</MyriadFile>
+    </Compile>
+    <Compile Include="List.fs" />
+    <Compile Include="ListCata.fs">
+      <MyriadFile>List.fs</MyriadFile>
+    </Compile>
   </ItemGroup>
 
   <ItemGroup>
     <PackageReference Include="RestEase" Version="1.6.4"/>
+    <ProjectReference Include="..\WoofWare.Myriad.Plugins.Attributes\WoofWare.Myriad.Plugins.Attributes.fsproj" />
     <ProjectReference Include="..\WoofWare.Myriad.Plugins\WoofWare.Myriad.Plugins.fsproj"/>
     <PackageReference Include="Myriad.Sdk" Version="0.8.3"/>
     <PackageReference Include="Myriad.Core" Version="0.8.3"/>

ConsumePlugin/FSharpForFunAndProfitCata.fs

@@ -0,0 +1,52 @@
+namespace ConsumePlugin
+
+open WoofWare.Myriad.Plugins
+
+type File =
+    {
+        Name : string
+        FileSize : int
+    }
+
+type Directory =
+    {
+        Name : string
+        DirSize : int
+        Contents : FileSystemItem list
+    }
+
+and [<CreateCatamorphism "FileSystemCata">] FileSystemItem =
+    | Directory of Directory
+    | File of File
+
+type Book =
+    {
+        title : string
+        price : decimal
+    }
+
+type ChocolateType =
+    | Dark
+    | Milk
+    | SeventyPercent
+
+type Chocolate =
+    {
+        chocType : ChocolateType
+        price : decimal
+    }
+
+    override this.ToString () = this.chocType.ToString ()
+
+type WrappingPaperStyle =
+    | HappyBirthday
+    | HappyHolidays
+    | SolidColor
+
+[<CreateCatamorphism "GiftCata">]
+type Gift =
+    | Book of Book
+    | Chocolate of Chocolate
+    | Wrapped of Gift * WrappingPaperStyle
+    | Boxed of Gift
+    | WithACard of Gift * message : string

ConsumePlugin/GeneratedCatamorphism.fs

@@ -0,0 +1,138 @@
+//------------------------------------------------------------------------------
+//        This code was generated by myriad.
+//        Changes to this file will be lost when the code is regenerated.
+//------------------------------------------------------------------------------
+
+
+
+
+
+namespace ConsumePlugin
+
+open WoofWare.Myriad.Plugins
+
+/// Description of how to combine cases during a fold
+type TreeBuilderCataCase<'b, 'a, 'TreeBuilder, 'Tree> =
+    /// How to operate on the Child case
+    abstract Child : 'TreeBuilder -> 'TreeBuilder
+    /// How to operate on the Parent case
+    abstract Parent : 'Tree -> 'TreeBuilder
+
+/// Description of how to combine cases during a fold
+type TreeCataCase<'a, 'b, 'TreeBuilder, 'Tree> =
+    /// How to operate on the Const case
+    abstract Const : Const<'a> -> 'b -> 'Tree
+    /// How to operate on the Pair case
+    abstract Pair : 'Tree -> 'Tree -> PairOpKind -> 'Tree
+    /// How to operate on the Sequential case
+    abstract Sequential : 'Tree list -> 'Tree
+    /// How to operate on the Builder case
+    abstract Builder : 'Tree -> 'TreeBuilder -> 'Tree
+
+/// Specifies how to perform a fold (catamorphism) over the type Tree and its friends.
+type TreeCata<'b, 'a, 'TreeBuilder, 'Tree> =
+    {
+        /// How to perform a fold (catamorphism) over the type TreeBuilder
+        TreeBuilder : TreeBuilderCataCase<'b, 'a, 'TreeBuilder, 'Tree>
+        /// How to perform a fold (catamorphism) over the type Tree
+        Tree : TreeCataCase<'a, 'b, 'TreeBuilder, 'Tree>
+    }
+
+/// Methods to perform a catamorphism over the type Tree
+[<RequireQualifiedAccess>]
+module TreeCata =
+    [<RequireQualifiedAccess>]
+    type private Instruction<'b, 'a> =
+        | Process__TreeBuilder of TreeBuilder<'b, 'a>
+        | Process__Tree of Tree<'a, 'b>
+        | TreeBuilder_Child
+        | TreeBuilder_Parent
+        | Tree_Pair of PairOpKind
+        | Tree_Sequential of int
+        | Tree_Builder
+
+    let private loop (cata : TreeCata<'b, 'a, 'TreeBuilder, 'Tree>) (instructions : ResizeArray<Instruction<'b, 'a>>) =
+        let treeStack = ResizeArray<'Tree> ()
+        let treeBuilderStack = ResizeArray<'TreeBuilder> ()
+
+        while instructions.Count > 0 do
+            let currentInstruction = instructions.[instructions.Count - 1]
+            instructions.RemoveAt (instructions.Count - 1)
+
+            match currentInstruction with
+            | Instruction.Process__TreeBuilder x ->
+                match x with
+                | TreeBuilder.Child (arg0_0) ->
+                    instructions.Add Instruction.TreeBuilder_Child
+                    instructions.Add (Instruction.Process__TreeBuilder arg0_0)
+                | TreeBuilder.Parent (arg0_0) ->
+                    instructions.Add Instruction.TreeBuilder_Parent
+                    instructions.Add (Instruction.Process__Tree arg0_0)
+            | Instruction.Process__Tree x ->
+                match x with
+                | Tree.Const (arg0_0, arg1_0) -> cata.Tree.Const arg0_0 arg1_0 |> treeStack.Add
+                | Tree.Pair (arg0_0, arg1_0, arg2_0) ->
+                    instructions.Add (Instruction.Tree_Pair (arg2_0))
+                    instructions.Add (Instruction.Process__Tree arg0_0)
+                    instructions.Add (Instruction.Process__Tree arg1_0)
+                | Tree.Sequential (arg0_0) ->
+                    instructions.Add (Instruction.Tree_Sequential ((List.length arg0_0)))
+
+                    for elt in arg0_0 do
+                        instructions.Add (Instruction.Process__Tree elt)
+                | Tree.Builder (arg0_0, arg1_0) ->
+                    instructions.Add Instruction.Tree_Builder
+                    instructions.Add (Instruction.Process__Tree arg0_0)
+                    instructions.Add (Instruction.Process__TreeBuilder arg1_0)
+            | Instruction.TreeBuilder_Child ->
+                let arg0_0 = treeBuilderStack.[treeBuilderStack.Count - 1]
+                treeBuilderStack.RemoveAt (treeBuilderStack.Count - 1)
+                cata.TreeBuilder.Child arg0_0 |> treeBuilderStack.Add
+            | Instruction.TreeBuilder_Parent ->
+                let arg0_0 = treeStack.[treeStack.Count - 1]
+                treeStack.RemoveAt (treeStack.Count - 1)
+                cata.TreeBuilder.Parent arg0_0 |> treeBuilderStack.Add
+            | Instruction.Tree_Pair (arg2_0) ->
+                let arg0_0 = treeStack.[treeStack.Count - 1]
+                treeStack.RemoveAt (treeStack.Count - 1)
+                let arg1_0 = treeStack.[treeStack.Count - 1]
+                treeStack.RemoveAt (treeStack.Count - 1)
+                cata.Tree.Pair arg0_0 arg1_0 arg2_0 |> treeStack.Add
+            | Instruction.Tree_Sequential (arg0_0) ->
+                let arg0_0_len = arg0_0
+
+                let arg0_0 =
+                    seq {
+                        for i = treeStack.Count - 1 downto treeStack.Count - arg0_0 do
+                            yield treeStack.[i]
+                    }
+                    |> Seq.toList
+
+                treeStack.RemoveRange (treeStack.Count - arg0_0_len, arg0_0_len)
+                cata.Tree.Sequential arg0_0 |> treeStack.Add
+            | Instruction.Tree_Builder ->
+                let arg0_0 = treeStack.[treeStack.Count - 1]
+                treeStack.RemoveAt (treeStack.Count - 1)
+                let arg1_0 = treeBuilderStack.[treeBuilderStack.Count - 1]
+                treeBuilderStack.RemoveAt (treeBuilderStack.Count - 1)
+                cata.Tree.Builder arg0_0 arg1_0 |> treeStack.Add
+
+        treeBuilderStack, treeStack
+
+    /// Execute the catamorphism.
+    let runTreeBuilder
+        (cata : TreeCata<'b, 'a, 'TreeBuilderRet, 'TreeRet>)
+        (x : TreeBuilder<'b, 'a>)
+        : 'TreeBuilderRet
+        =
+        let instructions = ResizeArray ()
+        instructions.Add (Instruction.Process__TreeBuilder x)
+        let treeBuilderRetStack, treeRetStack = loop cata instructions
+        Seq.exactlyOne treeBuilderRetStack
+
+    /// Execute the catamorphism.
+    let runTree (cata : TreeCata<'b, 'a, 'TreeBuilderRet, 'TreeRet>) (x : Tree<'a, 'b>) : 'TreeRet =
+        let instructions = ResizeArray ()
+        instructions.Add (Instruction.Process__Tree x)
+        let treeBuilderRetStack, treeRetStack = loop cata instructions
+        Seq.exactlyOne treeRetStack

ConsumePlugin/GeneratedFileSystem.fs

@@ -0,0 +1,152 @@
+//------------------------------------------------------------------------------
+//        This code was generated by myriad.
+//        Changes to this file will be lost when the code is regenerated.
+//------------------------------------------------------------------------------
+
+
+
+
+
+namespace ConsumePlugin
+
+open WoofWare.Myriad.Plugins
+
+/// Description of how to combine cases during a fold
+type FileSystemItemCataCase<'FileSystemItem> =
+    /// How to operate on the Directory case
+    abstract Directory : name : string -> dirSize : int -> contents : 'FileSystemItem list -> 'FileSystemItem
+    /// How to operate on the File case
+    abstract File : File -> 'FileSystemItem
+
+/// Specifies how to perform a fold (catamorphism) over the type FileSystemItem and its friends.
+type FileSystemCata<'FileSystemItem> =
+    {
+        /// How to perform a fold (catamorphism) over the type FileSystemItem
+        FileSystemItem : FileSystemItemCataCase<'FileSystemItem>
+    }
+
+/// Methods to perform a catamorphism over the type FileSystemItem
+[<RequireQualifiedAccess>]
+module FileSystemItemCata =
+    [<RequireQualifiedAccess>]
+    type private Instruction =
+        | Process__FileSystemItem of FileSystemItem
+        | FileSystemItem_Directory of string * int * int
+
+    let private loop (cata : FileSystemCata<'FileSystemItem>) (instructions : ResizeArray<Instruction>) =
+        let fileSystemItemStack = ResizeArray<'FileSystemItem> ()
+
+        while instructions.Count > 0 do
+            let currentInstruction = instructions.[instructions.Count - 1]
+            instructions.RemoveAt (instructions.Count - 1)
+
+            match currentInstruction with
+            | Instruction.Process__FileSystemItem x ->
+                match x with
+                | FileSystemItem.Directory ({
+                                                Name = name
+                                                DirSize = dirSize
+                                                Contents = contents
+                                            }) ->
+                    instructions.Add (Instruction.FileSystemItem_Directory (name, dirSize, (List.length contents)))
+
+                    for elt in contents do
+                        instructions.Add (Instruction.Process__FileSystemItem elt)
+                | FileSystemItem.File (arg0_0) -> cata.FileSystemItem.File arg0_0 |> fileSystemItemStack.Add
+            | Instruction.FileSystemItem_Directory (name, dirSize, contents) ->
+                let contents_len = contents
+
+                let contents =
+                    seq {
+                        for i = fileSystemItemStack.Count - 1 downto fileSystemItemStack.Count - contents do
+                            yield fileSystemItemStack.[i]
+                    }
+                    |> Seq.toList
+
+                fileSystemItemStack.RemoveRange (fileSystemItemStack.Count - contents_len, contents_len)
+                cata.FileSystemItem.Directory name dirSize contents |> fileSystemItemStack.Add
+
+        fileSystemItemStack
+
+    /// Execute the catamorphism.
+    let runFileSystemItem (cata : FileSystemCata<'FileSystemItemRet>) (x : FileSystemItem) : 'FileSystemItemRet =
+        let instructions = ResizeArray ()
+        instructions.Add (Instruction.Process__FileSystemItem x)
+        let fileSystemItemRetStack = loop cata instructions
+        Seq.exactlyOne fileSystemItemRetStack
+namespace ConsumePlugin
+
+open WoofWare.Myriad.Plugins
+
+/// Description of how to combine cases during a fold
+type GiftCataCase<'Gift> =
+    /// How to operate on the Book case
+    abstract Book : Book -> 'Gift
+    /// How to operate on the Chocolate case
+    abstract Chocolate : Chocolate -> 'Gift
+    /// How to operate on the Wrapped case
+    abstract Wrapped : 'Gift -> WrappingPaperStyle -> 'Gift
+    /// How to operate on the Boxed case
+    abstract Boxed : 'Gift -> 'Gift
+    /// How to operate on the WithACard case
+    abstract WithACard : 'Gift -> message : string -> 'Gift
+
+/// Specifies how to perform a fold (catamorphism) over the type Gift and its friends.
+type GiftCata<'Gift> =
+    {
+        /// How to perform a fold (catamorphism) over the type Gift
+        Gift : GiftCataCase<'Gift>
+    }
+
+/// Methods to perform a catamorphism over the type Gift
+[<RequireQualifiedAccess>]
+module GiftCata =
+    [<RequireQualifiedAccess>]
+    type private Instruction =
+        | Process__Gift of Gift
+        | Gift_Wrapped of WrappingPaperStyle
+        | Gift_Boxed
+        | Gift_WithACard of string
+
+    let private loop (cata : GiftCata<'Gift>) (instructions : ResizeArray<Instruction>) =
+        let giftStack = ResizeArray<'Gift> ()
+
+        while instructions.Count > 0 do
+            let currentInstruction = instructions.[instructions.Count - 1]
+            instructions.RemoveAt (instructions.Count - 1)
+
+            match currentInstruction with
+            | Instruction.Process__Gift x ->
+                match x with
+                | Gift.Book (arg0_0) -> cata.Gift.Book arg0_0 |> giftStack.Add
+                | Gift.Chocolate (arg0_0) -> cata.Gift.Chocolate arg0_0 |> giftStack.Add
+                | Gift.Wrapped (arg0_0, arg1_0) ->
+                    instructions.Add (Instruction.Gift_Wrapped (arg1_0))
+                    instructions.Add (Instruction.Process__Gift arg0_0)
+                | Gift.Boxed (arg0_0) ->
+                    instructions.Add Instruction.Gift_Boxed
+                    instructions.Add (Instruction.Process__Gift arg0_0)
+                | Gift.WithACard (arg0_0, message) ->
+                    instructions.Add (Instruction.Gift_WithACard (message))
+                    instructions.Add (Instruction.Process__Gift arg0_0)
+            | Instruction.Gift_Wrapped (arg1_0) ->
+                let arg0_0 = giftStack.[giftStack.Count - 1]
+                giftStack.RemoveAt (giftStack.Count - 1)
+                cata.Gift.Wrapped arg0_0 arg1_0 |> giftStack.Add
+            | Instruction.Gift_Boxed ->
+                let arg0_0 = giftStack.[giftStack.Count - 1]
+                giftStack.RemoveAt (giftStack.Count - 1)
+                cata.Gift.Boxed arg0_0 |> giftStack.Add
+            | Instruction.Gift_WithACard (message) ->
+                let arg0_0 = giftStack.[giftStack.Count - 1]
+                giftStack.RemoveAt (giftStack.Count - 1)
+                cata.Gift.WithACard arg0_0 message |> giftStack.Add
+
+        giftStack
+
+    /// Execute the catamorphism.
+    let runGift (cata : GiftCata<'GiftRet>) (x : Gift) : 'GiftRet =
+        let instructions = ResizeArray ()
+        instructions.Add (Instruction.Process__Gift x)
+        let giftRetStack = loop cata instructions
+        Seq.exactlyOne giftRetStack

ConsumePlugin/GeneratedMock.fs

@@ -5,6 +5,9 @@
 
 namespace SomeNamespace
 
+open System
+open WoofWare.Myriad.Plugins
+
 /// Mock record type for an interface
 type internal PublicTypeMock =
     {
@@ -13,6 +16,7 @@ type internal PublicTypeMock =
         Mem3 : int * option<System.Threading.CancellationToken> -> string
     }
 
+    /// An implementation where every method throws.
     static member Empty : PublicTypeMock =
         {
             Mem1 = (fun x -> raise (System.NotImplementedException "Unimplemented mock function"))
@@ -22,10 +26,38 @@ type internal PublicTypeMock =
 
     interface IPublicType with
         member this.Mem1 (arg_0_0, arg_0_1) = this.Mem1 (arg_0_0, arg_0_1)
-        member this.Mem2 (arg_0_0) = this.Mem2 (arg_0_0)
+        member this.Mem2 arg_0_0 = this.Mem2 (arg_0_0)
         member this.Mem3 (arg_0_0, arg_0_1) = this.Mem3 (arg_0_0, arg_0_1)
 namespace SomeNamespace
 
+open System
+open WoofWare.Myriad.Plugins
+
+/// Mock record type for an interface
+type public PublicTypeInternalFalseMock =
+    {
+        Mem1 : string * int -> string list
+        Mem2 : string -> int
+        Mem3 : int * option<System.Threading.CancellationToken> -> string
+    }
+
+    /// An implementation where every method throws.
+    static member Empty : PublicTypeInternalFalseMock =
+        {
+            Mem1 = (fun x -> raise (System.NotImplementedException "Unimplemented mock function"))
+            Mem2 = (fun x -> raise (System.NotImplementedException "Unimplemented mock function"))
+            Mem3 = (fun x -> raise (System.NotImplementedException "Unimplemented mock function"))
+        }
+
+    interface IPublicTypeInternalFalse with
+        member this.Mem1 (arg_0_0, arg_0_1) = this.Mem1 (arg_0_0, arg_0_1)
+        member this.Mem2 arg_0_0 = this.Mem2 (arg_0_0)
+        member this.Mem3 (arg_0_0, arg_0_1) = this.Mem3 (arg_0_0, arg_0_1)
+namespace SomeNamespace
+
+open System
+open WoofWare.Myriad.Plugins
+
 /// Mock record type for an interface
 type internal InternalTypeMock =
     {
@@ -33,6 +65,7 @@ type internal InternalTypeMock =
         Mem2 : string -> int
     }
 
+    /// An implementation where every method throws.
     static member Empty : InternalTypeMock =
         {
             Mem1 = (fun x -> raise (System.NotImplementedException "Unimplemented mock function"))
@@ -41,9 +74,12 @@ type internal InternalTypeMock =
 
     interface InternalType with
         member this.Mem1 (arg_0_0, arg_0_1) = this.Mem1 (arg_0_0, arg_0_1)
-        member this.Mem2 (arg_0_0) = this.Mem2 (arg_0_0)
+        member this.Mem2 arg_0_0 = this.Mem2 (arg_0_0)
 namespace SomeNamespace
 
+open System
+open WoofWare.Myriad.Plugins
+
 /// Mock record type for an interface
 type private PrivateTypeMock =
     {
@@ -51,6 +87,7 @@ type private PrivateTypeMock =
         Mem2 : string -> int
     }
 
+    /// An implementation where every method throws.
     static member Empty : PrivateTypeMock =
         {
             Mem1 = (fun x -> raise (System.NotImplementedException "Unimplemented mock function"))
@@ -59,24 +96,53 @@ type private PrivateTypeMock =
 
     interface PrivateType with
         member this.Mem1 (arg_0_0, arg_0_1) = this.Mem1 (arg_0_0, arg_0_1)
-        member this.Mem2 (arg_0_0) = this.Mem2 (arg_0_0)
+        member this.Mem2 arg_0_0 = this.Mem2 (arg_0_0)
 namespace SomeNamespace
 
+open System
+open WoofWare.Myriad.Plugins
+
+/// Mock record type for an interface
+type private PrivateTypeInternalFalseMock =
+    {
+        Mem1 : string * int -> unit
+        Mem2 : string -> int
+    }
+
+    /// An implementation where every method throws.
+    static member Empty : PrivateTypeInternalFalseMock =
+        {
+            Mem1 = (fun x -> raise (System.NotImplementedException "Unimplemented mock function"))
+            Mem2 = (fun x -> raise (System.NotImplementedException "Unimplemented mock function"))
+        }
+
+    interface PrivateTypeInternalFalse with
+        member this.Mem1 (arg_0_0, arg_0_1) = this.Mem1 (arg_0_0, arg_0_1)
+        member this.Mem2 arg_0_0 = this.Mem2 (arg_0_0)
+namespace SomeNamespace
+
+open System
+open WoofWare.Myriad.Plugins
+
 /// Mock record type for an interface
 type internal VeryPublicTypeMock<'a, 'b> =
     {
         Mem1 : 'a -> 'b
     }
 
+    /// An implementation where every method throws.
     static member Empty () : VeryPublicTypeMock<'a, 'b> =
         {
             Mem1 = (fun x -> raise (System.NotImplementedException "Unimplemented mock function"))
         }
 
     interface VeryPublicType<'a, 'b> with
-        member this.Mem1 (arg_0_0) = this.Mem1 (arg_0_0)
+        member this.Mem1 arg_0_0 = this.Mem1 (arg_0_0)
 namespace SomeNamespace
 
+open System
+open WoofWare.Myriad.Plugins
+
 /// Mock record type for an interface
 type internal CurriedMock<'a> =
     {
@@ -88,6 +154,7 @@ type internal CurriedMock<'a> =
         Mem6 : int * string -> 'a * int -> string
     }
 
+    /// An implementation where every method throws.
     static member Empty () : CurriedMock<'a> =
         {
             Mem1 = (fun x -> raise (System.NotImplementedException "Unimplemented mock function"))
@@ -99,9 +166,9 @@ type internal CurriedMock<'a> =
         }
 
     interface Curried<'a> with
-        member this.Mem1 (arg_0_0) (arg_1_0) = this.Mem1 (arg_0_0) (arg_1_0)
-        member this.Mem2 (arg_0_0, arg_0_1) (arg_1_0) = this.Mem2 (arg_0_0, arg_0_1) (arg_1_0)
-        member this.Mem3 ((arg_0_0, arg_0_1)) (arg_1_0) = this.Mem3 (arg_0_0, arg_0_1) (arg_1_0)
+        member this.Mem1 arg_0_0 arg_1_0 = this.Mem1 (arg_0_0) (arg_1_0)
+        member this.Mem2 (arg_0_0, arg_0_1) arg_1_0 = this.Mem2 (arg_0_0, arg_0_1) (arg_1_0)
+        member this.Mem3 ((arg_0_0, arg_0_1)) arg_1_0 = this.Mem3 (arg_0_0, arg_0_1) (arg_1_0)
 
         member this.Mem4 ((arg_0_0, arg_0_1)) ((arg_1_0, arg_1_1)) =
             this.Mem4 (arg_0_0, arg_0_1) (arg_1_0, arg_1_1)
@@ -111,3 +178,31 @@ type internal CurriedMock<'a> =
 
         member this.Mem6 (arg_0_0, arg_0_1) (arg_1_0, arg_1_1) =
             this.Mem6 (arg_0_0, arg_0_1) (arg_1_0, arg_1_1)
+namespace SomeNamespace
+
+open System
+open WoofWare.Myriad.Plugins
+
+/// Mock record type for an interface
+type internal TypeWithInterfaceMock =
+    {
+        /// Implementation of IDisposable.Dispose
+        Dispose : unit -> unit
+        Mem1 : string option -> string[] Async
+        Mem2 : unit -> string[] Async
+    }
+
+    /// An implementation where every method throws.
+    static member Empty : TypeWithInterfaceMock =
+        {
+            Dispose = (fun _ -> ())
+            Mem1 = (fun x -> raise (System.NotImplementedException "Unimplemented mock function"))
+            Mem2 = (fun x -> raise (System.NotImplementedException "Unimplemented mock function"))
+        }
+
+    interface TypeWithInterface with
+        member this.Mem1 arg_0_0 = this.Mem1 (arg_0_0)
+        member this.Mem2 () = this.Mem2 (())
+
+    interface System.IDisposable with
+        member this.Dispose () : unit = this.Dispose ()

ConsumePlugin/GeneratedRestClient.fs

@@ -32,7 +32,7 @@ module PureGymApi =
                             (match client.BaseAddress with
                              | null -> System.Uri "https://whatnot.com"
                              | v -> v),
-                            System.Uri ("v1/gyms/", System.UriKind.Relative)
+                            System.Uri (("v1/gyms/"), System.UriKind.Relative)
                         )
 
                     let httpMessage =
@@ -117,7 +117,7 @@ module PureGymApi =
                 }
                 |> (fun a -> Async.StartAsTask (a, ?cancellationToken = ct))
 
-            member _.GetGym (gymId : int, ct : CancellationToken option) =
+            member _.GetGym (gym : int, ct : CancellationToken option) =
                 async {
                     let! ct = Async.CancellationToken
 
@@ -127,8 +127,8 @@ module PureGymApi =
                              | null -> System.Uri "https://whatnot.com"
                              | v -> v),
                             System.Uri (
-                                "v1/gyms/{gym_id}"
-                                    .Replace ("{gym_id}", gymId.ToString () |> System.Web.HttpUtility.UrlEncode),
+                                "v1/gyms/{gym}"
+                                    .Replace ("{gym}", gym.ToString () |> System.Web.HttpUtility.UrlEncode),
                                 System.UriKind.Relative
                             )
                         )
@@ -211,6 +211,72 @@ module PureGymApi =
                 }
                 |> (fun a -> Async.StartAsTask (a, ?cancellationToken = ct))
 
+            member _.PostStringToString (foo : Map<string, string> option, ct : CancellationToken option) =
+                async {
+                    let! ct = Async.CancellationToken
+
+                    let uri =
+                        System.Uri (
+                            (match client.BaseAddress with
+                             | null -> System.Uri "https://whatnot.com"
+                             | v -> v),
+                            System.Uri ("some/url", System.UriKind.Relative)
+                        )
+
+                    let httpMessage =
+                        new System.Net.Http.HttpRequestMessage (
+                            Method = System.Net.Http.HttpMethod.Post,
+                            RequestUri = uri
+                        )
+
+                    let queryParams =
+                        new System.Net.Http.StringContent (
+                            foo
+                            |> (fun field ->
+                                match field with
+                                | None -> null :> System.Text.Json.Nodes.JsonNode
+                                | Some field ->
+                                    ((fun field ->
+                                        let ret = System.Text.Json.Nodes.JsonObject ()
+
+                                        for (KeyValue (key, value)) in field do
+                                            ret.Add (
+                                                key.ToString (),
+                                                System.Text.Json.Nodes.JsonValue.Create<string> value
+                                            )
+
+                                        ret
+                                    )
+                                        field)
+                                    :> System.Text.Json.Nodes.JsonNode
+                            )
+                            |> (fun node -> if isNull node then "null" else node.ToJsonString ())
+                        )
+
+                    do httpMessage.Content <- queryParams
+                    let! response = client.SendAsync (httpMessage, ct) |> Async.AwaitTask
+                    let response = response.EnsureSuccessStatusCode ()
+                    let! responseStream = response.Content.ReadAsStreamAsync ct |> Async.AwaitTask
+
+                    let! jsonNode =
+                        System.Text.Json.Nodes.JsonNode.ParseAsync (responseStream, cancellationToken = ct)
+                        |> Async.AwaitTask
+
+                    return
+                        match jsonNode with
+                        | null -> None
+                        | v ->
+                            v.AsObject ()
+                            |> Seq.map (fun kvp ->
+                                let key = (kvp.Key)
+                                let value = (kvp.Value).AsValue().GetValue<string> ()
+                                key, value
+                            )
+                            |> Map.ofSeq
+                            |> Some
+                }
+                |> (fun a -> Async.StartAsTask (a, ?cancellationToken = ct))
+
             member _.GetSessions (fromDate : DateOnly, toDate : DateOnly, ct : CancellationToken option) =
                 async {
                     let! ct = Async.CancellationToken
@@ -222,7 +288,52 @@ module PureGymApi =
                              | v -> v),
                             System.Uri (
                                 ("/v2/gymSessions/member"
-                                 + "?fromDate="
+                                 + (if "/v2/gymSessions/member".IndexOf (char 63) > 0 then
+                                        "&"
+                                    else
+                                        "?")
+                                 + "fromDate="
+                                 + ((fromDate.ToString "yyyy-MM-dd") |> System.Web.HttpUtility.UrlEncode)
+                                 + "&toDate="
+                                 + ((toDate.ToString "yyyy-MM-dd") |> System.Web.HttpUtility.UrlEncode)),
+                                System.UriKind.Relative
+                            )
+                        )
+
+                    let httpMessage =
+                        new System.Net.Http.HttpRequestMessage (
+                            Method = System.Net.Http.HttpMethod.Get,
+                            RequestUri = uri
+                        )
+
+                    let! response = client.SendAsync (httpMessage, ct) |> Async.AwaitTask
+                    let response = response.EnsureSuccessStatusCode ()
+                    let! responseStream = response.Content.ReadAsStreamAsync ct |> Async.AwaitTask
+
+                    let! jsonNode =
+                        System.Text.Json.Nodes.JsonNode.ParseAsync (responseStream, cancellationToken = ct)
+                        |> Async.AwaitTask
+
+                    return Sessions.jsonParse jsonNode
+                }
+                |> (fun a -> Async.StartAsTask (a, ?cancellationToken = ct))
+
+            member _.GetSessionsWithQuery (fromDate : DateOnly, toDate : DateOnly, ct : CancellationToken option) =
+                async {
+                    let! ct = Async.CancellationToken
+
+                    let uri =
+                        System.Uri (
+                            (match client.BaseAddress with
+                             | null -> System.Uri "https://whatnot.com"
+                             | v -> v),
+                            System.Uri (
+                                ("/v2/gymSessions/member?foo=1"
+                                 + (if "/v2/gymSessions/member?foo=1".IndexOf (char 63) > 0 then
+                                        "&"
+                                    else
+                                        "?")
+                                 + "fromDate="
                                  + ((fromDate.ToString "yyyy-MM-dd") |> System.Web.HttpUtility.UrlEncode)
                                  + "&toDate="
                                  + ((toDate.ToString "yyyy-MM-dd") |> System.Web.HttpUtility.UrlEncode)),
@@ -403,7 +514,9 @@ module PureGymApi =
 
                     let queryParams =
                         new System.Net.Http.StringContent (
-                            user |> PureGym.Member.toJsonNode |> (fun node -> node.ToJsonString ())
+                            user
+                            |> PureGym.Member.toJsonNode
+                            |> (fun node -> if isNull node then "null" else node.ToJsonString ())
                         )
 
                     do httpMessage.Content <- queryParams
@@ -436,7 +549,7 @@ module PureGymApi =
                         new System.Net.Http.StringContent (
                             user
                             |> System.Text.Json.Nodes.JsonValue.Create<Uri>
-                            |> (fun node -> node.ToJsonString ())
+                            |> (fun node -> if isNull node then "null" else node.ToJsonString ())
                         )
 
                     do httpMessage.Content <- queryParams
@@ -469,7 +582,7 @@ module PureGymApi =
                         new System.Net.Http.StringContent (
                             user
                             |> System.Text.Json.Nodes.JsonValue.Create<int>
-                            |> (fun node -> node.ToJsonString ())
+                            |> (fun node -> if isNull node then "null" else node.ToJsonString ())
                         )
 
                     do httpMessage.Content <- queryParams
@@ -966,7 +1079,7 @@ module ApiWithBasePath =
     /// Create a REST client.
     let make (client : System.Net.Http.HttpClient) : IApiWithBasePath =
         { new IApiWithBasePath with
-            member _.GetPathParam (parameter : string, ct : CancellationToken option) =
+            member _.GetPathParam (parameter : string, cancellationToken : CancellationToken option) =
                 async {
                     let! ct = Async.CancellationToken
 
@@ -999,7 +1112,7 @@ module ApiWithBasePath =
                     let! responseString = response.Content.ReadAsStringAsync ct |> Async.AwaitTask
                     return responseString
                 }
-                |> (fun a -> Async.StartAsTask (a, ?cancellationToken = ct))
+                |> (fun a -> Async.StartAsTask (a, ?cancellationToken = cancellationToken))
         }
 namespace PureGym
 
@@ -1047,3 +1160,129 @@ module ApiWithBasePathAndAddress =
                 }
                 |> (fun a -> Async.StartAsTask (a, ?cancellationToken = ct))
         }
+namespace PureGym
+
+open System
+open System.Threading
+open System.Threading.Tasks
+open System.IO
+open System.Net
+open System.Net.Http
+open RestEase
+
+/// Module for constructing a REST client.
+[<CompilationRepresentation(CompilationRepresentationFlags.ModuleSuffix)>]
+[<RequireQualifiedAccess>]
+module ApiWithHeaders =
+    /// Create a REST client. The input functions will be re-evaluated on every HTTP request to obtain the required values for the corresponding header properties.
+    let make
+        (someHeader : unit -> string)
+        (someOtherHeader : unit -> int)
+        (client : System.Net.Http.HttpClient)
+        : IApiWithHeaders
+        =
+        { new IApiWithHeaders with
+            member _.SomeHeader : string = someHeader ()
+            member _.SomeOtherHeader : int = someOtherHeader ()
+
+            member this.GetPathParam (parameter : string, ct : CancellationToken option) =
+                async {
+                    let! ct = Async.CancellationToken
+
+                    let uri =
+                        System.Uri (
+                            (match client.BaseAddress with
+                             | null ->
+                                 raise (
+                                     System.ArgumentNullException (
+                                         nameof (client.BaseAddress),
+                                         "No base address was supplied on the type, and no BaseAddress was on the HttpClient."
+                                     )
+                                 )
+                             | v -> v),
+                            System.Uri (
+                                "endpoint/{param}"
+                                    .Replace ("{param}", parameter.ToString () |> System.Web.HttpUtility.UrlEncode),
+                                System.UriKind.Relative
+                            )
+                        )
+
+                    let httpMessage =
+                        new System.Net.Http.HttpRequestMessage (
+                            Method = System.Net.Http.HttpMethod.Get,
+                            RequestUri = uri
+                        )
+
+                    do httpMessage.Headers.Add ("X-Foo", this.SomeHeader.ToString ())
+                    do httpMessage.Headers.Add ("Authorization", this.SomeOtherHeader.ToString ())
+                    do httpMessage.Headers.Add ("Header-Name", "Header-Value")
+                    let! response = client.SendAsync (httpMessage, ct) |> Async.AwaitTask
+                    let response = response.EnsureSuccessStatusCode ()
+                    let! responseString = response.Content.ReadAsStringAsync ct |> Async.AwaitTask
+                    return responseString
+                }
+                |> (fun a -> Async.StartAsTask (a, ?cancellationToken = ct))
+        }
+namespace PureGym
+
+open System
+open System.Threading
+open System.Threading.Tasks
+open System.IO
+open System.Net
+open System.Net.Http
+open RestEase
+
+/// Module for constructing a REST client.
+[<CompilationRepresentation(CompilationRepresentationFlags.ModuleSuffix)>]
+[<RequireQualifiedAccess>]
+module ApiWithHeaders2 =
+    /// Create a REST client. The input functions will be re-evaluated on every HTTP request to obtain the required values for the corresponding header properties.
+    let make
+        (someHeader : unit -> string)
+        (someOtherHeader : unit -> int)
+        (client : System.Net.Http.HttpClient)
+        : IApiWithHeaders2
+        =
+        { new IApiWithHeaders2 with
+            member _.SomeHeader : string = someHeader ()
+            member _.SomeOtherHeader : int = someOtherHeader ()
+
+            member this.GetPathParam (parameter : string, ct : CancellationToken option) =
+                async {
+                    let! ct = Async.CancellationToken
+
+                    let uri =
+                        System.Uri (
+                            (match client.BaseAddress with
+                             | null ->
+                                 raise (
+                                     System.ArgumentNullException (
+                                         nameof (client.BaseAddress),
+                                         "No base address was supplied on the type, and no BaseAddress was on the HttpClient."
+                                     )
+                                 )
+                             | v -> v),
+                            System.Uri (
+                                "endpoint/{param}"
+                                    .Replace ("{param}", parameter.ToString () |> System.Web.HttpUtility.UrlEncode),
+                                System.UriKind.Relative
+                            )
+                        )
+
+                    let httpMessage =
+                        new System.Net.Http.HttpRequestMessage (
+                            Method = System.Net.Http.HttpMethod.Get,
+                            RequestUri = uri
+                        )
+
+                    do httpMessage.Headers.Add ("X-Foo", this.SomeHeader.ToString ())
+                    do httpMessage.Headers.Add ("Authorization", this.SomeOtherHeader.ToString ())
+                    do httpMessage.Headers.Add ("Header-Name", "Header-Value")
+                    let! response = client.SendAsync (httpMessage, ct) |> Async.AwaitTask
+                    let response = response.EnsureSuccessStatusCode ()
+                    let! responseString = response.Content.ReadAsStringAsync ct |> Async.AwaitTask
+                    return responseString
+                }
+                |> (fun a -> Async.StartAsTask (a, ?cancellationToken = ct))
+        }

ConsumePlugin/GeneratedSerde.fs

@@ -21,7 +21,7 @@ module InnerTypeWithBothJsonSerializeExtension =
             let node = System.Text.Json.Nodes.JsonObject ()
 
             do
-                node.Add (("it's-a-me"), System.Text.Json.Nodes.JsonValue.Create<string> input.Thing)
+                node.Add (("it's-a-me"), System.Text.Json.Nodes.JsonValue.Create<Guid> input.Thing)
 
                 node.Add (
                     "map",
@@ -245,6 +245,7 @@ module InnerTypeWithBothJsonParseExtension =
                  | v -> v)
                     .AsValue()
                     .GetValue<string> ()
+                |> System.Guid.Parse
 
             {
                 Thing = Thing

ConsumePlugin/GeneratedVault.fs

@@ -462,12 +462,7 @@ module VaultClient =
     let make (client : System.Net.Http.HttpClient) : IVaultClient =
         { new IVaultClient with
             member _.GetSecret
-                (
-                    jwt : JwtVaultResponse,
-                    path : string,
-                    mountPoint : string,
-                    ct : CancellationToken option
-                )
+                (jwt : JwtVaultResponse, path : string, mountPoint : string, ct : CancellationToken option)
                 =
                 async {
                     let! ct = Async.CancellationToken

ConsumePlugin/List.fs

@@ -0,0 +1,19 @@
+namespace ConsumePlugin
+
+open WoofWare.Myriad.Plugins
+
+[<CreateCatamorphism "MyListCata">]
+type MyList<'a> =
+    | Nil
+    | Cons of ConsCase<'a>
+
+and ConsCase<'a> =
+    {
+        Head : 'a
+        Tail : MyList<'a>
+    }
+
+[<CreateCatamorphism "MyList2Cata">]
+type MyList2<'a> =
+    | Nil
+    | Cons of 'a * MyList2<'a>

ConsumePlugin/ListCata.fs

@@ -0,0 +1,118 @@
+//------------------------------------------------------------------------------
+//        This code was generated by myriad.
+//        Changes to this file will be lost when the code is regenerated.
+//------------------------------------------------------------------------------
+
+
+
+
+
+namespace ConsumePlugin
+
+open WoofWare.Myriad.Plugins
+
+/// Description of how to combine cases during a fold
+type MyListCataCase<'a, 'MyList> =
+    /// How to operate on the Nil case
+    abstract Nil : 'MyList
+    /// How to operate on the Cons case
+    abstract Cons : head : 'a -> tail : 'MyList -> 'MyList
+
+/// Specifies how to perform a fold (catamorphism) over the type MyList and its friends.
+type MyListCata<'a, 'MyList> =
+    {
+        /// How to perform a fold (catamorphism) over the type MyList
+        MyList : MyListCataCase<'a, 'MyList>
+    }
+
+/// Methods to perform a catamorphism over the type MyList
+[<RequireQualifiedAccess>]
+module MyListCata =
+    [<RequireQualifiedAccess>]
+    type private Instruction<'a> =
+        | Process__MyList of MyList<'a>
+        | MyList_Cons of 'a
+
+    let private loop (cata : MyListCata<'a, 'MyList>) (instructions : ResizeArray<Instruction<'a>>) =
+        let myListStack = ResizeArray<'MyList> ()
+
+        while instructions.Count > 0 do
+            let currentInstruction = instructions.[instructions.Count - 1]
+            instructions.RemoveAt (instructions.Count - 1)
+
+            match currentInstruction with
+            | Instruction.Process__MyList x ->
+                match x with
+                | MyList.Nil -> cata.MyList.Nil |> myListStack.Add
+                | MyList.Cons ({
+                                   Head = head
+                                   Tail = tail
+                               }) ->
+                    instructions.Add (Instruction.MyList_Cons (head))
+                    instructions.Add (Instruction.Process__MyList tail)
+            | Instruction.MyList_Cons (head) ->
+                let tail = myListStack.[myListStack.Count - 1]
+                myListStack.RemoveAt (myListStack.Count - 1)
+                cata.MyList.Cons head tail |> myListStack.Add
+
+        myListStack
+
+    /// Execute the catamorphism.
+    let runMyList (cata : MyListCata<'a, 'MyListRet>) (x : MyList<'a>) : 'MyListRet =
+        let instructions = ResizeArray ()
+        instructions.Add (Instruction.Process__MyList x)
+        let myListRetStack = loop cata instructions
+        Seq.exactlyOne myListRetStack
+namespace ConsumePlugin
+
+open WoofWare.Myriad.Plugins
+
+/// Description of how to combine cases during a fold
+type MyList2CataCase<'a, 'MyList2> =
+    /// How to operate on the Nil case
+    abstract Nil : 'MyList2
+    /// How to operate on the Cons case
+    abstract Cons : 'a -> 'MyList2 -> 'MyList2
+
+/// Specifies how to perform a fold (catamorphism) over the type MyList2 and its friends.
+type MyList2Cata<'a, 'MyList2> =
+    {
+        /// How to perform a fold (catamorphism) over the type MyList2
+        MyList2 : MyList2CataCase<'a, 'MyList2>
+    }
+
+/// Methods to perform a catamorphism over the type MyList2
+[<RequireQualifiedAccess>]
+module MyList2Cata =
+    [<RequireQualifiedAccess>]
+    type private Instruction<'a> =
+        | Process__MyList2 of MyList2<'a>
+        | MyList2_Cons of 'a
+
+    let private loop (cata : MyList2Cata<'a, 'MyList2>) (instructions : ResizeArray<Instruction<'a>>) =
+        let myList2Stack = ResizeArray<'MyList2> ()
+
+        while instructions.Count > 0 do
+            let currentInstruction = instructions.[instructions.Count - 1]
+            instructions.RemoveAt (instructions.Count - 1)
+
+            match currentInstruction with
+            | Instruction.Process__MyList2 x ->
+                match x with
+                | MyList2.Nil -> cata.MyList2.Nil |> myList2Stack.Add
+                | MyList2.Cons (arg0_0, arg1_0) ->
+                    instructions.Add (Instruction.MyList2_Cons (arg0_0))
+                    instructions.Add (Instruction.Process__MyList2 arg1_0)
+            | Instruction.MyList2_Cons (arg0_0) ->
+                let arg1_0 = myList2Stack.[myList2Stack.Count - 1]
+                myList2Stack.RemoveAt (myList2Stack.Count - 1)
+                cata.MyList2.Cons arg0_0 arg1_0 |> myList2Stack.Add
+
+        myList2Stack
+
+    /// Execute the catamorphism.
+    let runMyList2 (cata : MyList2Cata<'a, 'MyList2Ret>) (x : MyList2<'a>) : 'MyList2Ret =
+        let instructions = ResizeArray ()
+        instructions.Add (Instruction.Process__MyList2 x)
+        let myList2RetStack = loop cata instructions
+        Seq.exactlyOne myList2RetStack

ConsumePlugin/MockExample.fs

@@ -1,5 +1,6 @@
 namespace SomeNamespace
 
+open System
 open WoofWare.Myriad.Plugins
 
 [<GenerateMock>]
@@ -8,6 +9,12 @@ type IPublicType =
     abstract Mem2 : string -> int
     abstract Mem3 : x : int * ?ct : System.Threading.CancellationToken -> string
 
+[<GenerateMock false>]
+type IPublicTypeInternalFalse =
+    abstract Mem1 : string * int -> string list
+    abstract Mem2 : string -> int
+    abstract Mem3 : x : int * ?ct : System.Threading.CancellationToken -> string
+
 [<GenerateMock>]
 type internal InternalType =
     abstract Mem1 : string * int -> unit
@@ -18,6 +25,11 @@ type private PrivateType =
     abstract Mem1 : string * int -> unit
     abstract Mem2 : string -> int
 
+[<GenerateMock false>]
+type private PrivateTypeInternalFalse =
+    abstract Mem1 : string * int -> unit
+    abstract Mem2 : string -> int
+
 [<GenerateMock>]
 type VeryPublicType<'a, 'b> =
     abstract Mem1 : 'a -> 'b
@@ -30,3 +42,9 @@ type Curried<'a> =
     abstract Mem4 : (int * string) -> ('a * int) -> string
     abstract Mem5 : x : int * string -> ('a * int) -> string
     abstract Mem6 : int * string -> y : 'a * int -> string
+
+[<GenerateMock>]
+type TypeWithInterface =
+    inherit IDisposable
+    abstract Mem1 : string option -> string[] Async
+    abstract Mem2 : unit -> string[] Async

ConsumePlugin/RestApiExample.fs

@@ -11,7 +11,7 @@ open RestEase
 [<WoofWare.Myriad.Plugins.HttpClient>]
 [<BaseAddress "https://whatnot.com">]
 type IPureGymApi =
-    [<Get "v1/gyms/">]
+    [<Get("v1/gyms/")>]
     abstract GetGyms : ?ct : CancellationToken -> Task<Gym list>
 
     [<Get "v1/gyms/{gym_id}/attendance">]
@@ -20,8 +20,8 @@ type IPureGymApi =
     [<RestEase.GetAttribute "v1/member">]
     abstract GetMember : ?ct : CancellationToken -> Member Task
 
-    [<RestEase.Get "v1/gyms/{gym_id}">]
-    abstract GetGym : [<Path "gym_id">] gymId : int * ?ct : CancellationToken -> Task<Gym>
+    [<RestEase.Get "v1/gyms/{gym}">]
+    abstract GetGym : [<Path>] gym : int * ?ct : CancellationToken -> Task<Gym>
 
     [<GetAttribute "v1/member/activity">]
     abstract GetMemberActivity : ?ct : CancellationToken -> Task<MemberActivityDto>
@@ -29,11 +29,19 @@ type IPureGymApi =
     [<Get "some/url">]
     abstract GetUrl : ?ct : CancellationToken -> Task<UriThing>
 
+    [<Post "some/url">]
+    abstract PostStringToString :
+        [<Body>] foo : Map<string, string> option * ?ct : CancellationToken -> Task<Map<string, string> option>
+
     // We'll use this one to check handling of absolute URIs too
     [<Get "/v2/gymSessions/member">]
     abstract GetSessions :
         [<Query>] fromDate : DateOnly * [<Query>] toDate : DateOnly * ?ct : CancellationToken -> Task<Sessions>
 
+    [<Get "/v2/gymSessions/member?foo=1">]
+    abstract GetSessionsWithQuery :
+        [<Query>] fromDate : DateOnly * [<Query>] toDate : DateOnly * ?ct : CancellationToken -> Task<Sessions>
+
     // An example from RestEase's own docs
     [<Post "users/new">]
     abstract CreateUserString : [<Body>] user : string * ?ct : CancellationToken -> Task<string>
@@ -116,8 +124,9 @@ type internal IApiWithoutBaseAddress =
 [<WoofWare.Myriad.Plugins.HttpClient>]
 [<BasePath "foo">]
 type IApiWithBasePath =
-    [<Get "endpoint/{param}">]
-    abstract GetPathParam : [<Path "param">] parameter : string * ?ct : CancellationToken -> Task<string>
+    // Example where we use the bundled attributes rather than RestEase's
+    [<WoofWare.Myriad.Plugins.RestEase.Get "endpoint/{param}">]
+    abstract GetPathParam : [<Path "param">] parameter : string * ?cancellationToken : CancellationToken -> Task<string>
 
 [<WoofWare.Myriad.Plugins.HttpClient>]
 [<BaseAddress "https://whatnot.com">]
@@ -125,3 +134,28 @@ type IApiWithBasePath =
 type IApiWithBasePathAndAddress =
     [<Get "endpoint/{param}">]
     abstract GetPathParam : [<Path "param">] parameter : string * ?ct : CancellationToken -> Task<string>
+
+[<WoofWare.Myriad.Plugins.HttpClient>]
+[<Header("Header-Name", "Header-Value")>]
+type IApiWithHeaders =
+    [<Header "X-Foo">]
+    abstract SomeHeader : string
+
+    [<Header "Authorization">]
+    abstract SomeOtherHeader : int
+
+    [<Get "endpoint/{param}">]
+    abstract GetPathParam : [<Path "param">] parameter : string * ?ct : CancellationToken -> Task<string>
+
+[<WoofWare.Myriad.Plugins.HttpClient>]
+[<WoofWare.Myriad.Plugins.RestEase.Header("Header-Name", "Header-Value")>]
+type IApiWithHeaders2 =
+    [<WoofWare.Myriad.Plugins.RestEase.Header "X-Foo">]
+    abstract SomeHeader : string
+
+    [<WoofWare.Myriad.Plugins.RestEase.Header "Authorization">]
+    abstract SomeOtherHeader : int
+
+    [<Get "endpoint/{param}">]
+    abstract GetPathParam :
+        [<WoofWare.Myriad.Plugins.RestEase.Path "param">] parameter : string * ?ct : CancellationToken -> Task<string>

ConsumePlugin/SerializationAndDeserialization.fs

@@ -9,7 +9,7 @@ open System.Text.Json.Serialization
 type InnerTypeWithBoth =
     {
         [<JsonPropertyName("it's-a-me")>]
-        Thing : string
+        Thing : Guid
         Map : Map<string, Uri>
         ReadOnlyDict : IReadOnlyDictionary<string, char list>
         Dict : IDictionary<Uri, bool>

README.md

@@ -1,375 +1,463 @@
-# WoofWare.Myriad.Plugins
-
-[![NuGet version](https://img.shields.io/nuget/v/WoofWare.Myriad.Plugins.svg?style=flat-square)](https://www.nuget.org/packages/WoofWare.Myriad.Plugins)
-[![GitHub Actions status](https://github.com/Smaug123/WoofWare.Myriad/actions/workflows/dotnet.yaml/badge.svg)](https://github.com/Smaug123/WoofWare.Myriad/actions?query=branch%3Amain)
-[![License file](https://img.shields.io/github/license/Smaug123/WoofWare.Myriad)](./LICENSE)
-
-![Project logo: the face of a cartoon Shiba Inu, staring with powerful cyborg eyes directly at the viewer, with a background of stylised plugs.](./WoofWare.Myriad.Plugins/logo.png)
-
-Some helpers in [Myriad](https://github.com/MoiraeSoftware/myriad/) which might be useful.
-
-These are currently somewhat experimental, and I personally am their primary customer.
-The `RemoveOptions` generator in particular is extremely half-baked.
-
-If you would like to ensure that your particular use-case remains unbroken, please do contribute tests to this repository.
-The `ConsumePlugin` assembly contains a number of invocations of these source generators,
-so you just need to add copies of your types to that assembly to ensure that I will at least notice if I break the build;
-and if you add tests to `WoofWare.Myriad.Plugins.Test` then I will also notice if I break the runtime semantics of the generated code.
-
-Currently implemented:
-
-* `JsonParse` (to stamp out `jsonParse : JsonNode -> 'T` methods);
-* `JsonSerialize` (to stamp out `toJsonNode : 'T -> JsonNode` methods);
-* `RemoveOptions` (to strip `option` modifiers from a type).
-* `HttpClient` (to stamp out a [RestEase](https://github.com/canton7/RestEase)-style HTTP client).
-* `GenerateMock` (to stamp out a record type corresponding to an interface).
-
-## `JsonParse`
-
-Takes records like this:
-
-```fsharp
-[<WoofWare.Myriad.Plugins.JsonParse>]
-type InnerType =
-    {
-        [<JsonPropertyName "something">]
-        Thing : string
-    }
-
-/// My whatnot
-[<WoofWare.Myriad.Plugins.JsonParse>]
-type JsonRecordType =
-    {
-        /// A thing!
-        A : int
-        /// Another thing!
-        B : string
-        [<System.Text.Json.Serialization.JsonPropertyName "hi">]
-        C : int list
-        D : InnerType
-    }
-
-```
-
-and stamps out parsing methods like this:
-
-```fsharp
-/// Module containing JSON parsing methods for the InnerType type
-[<RequireQualifiedAccess>]
-[<CompilationRepresentation(CompilationRepresentationFlags.ModuleSuffix)>]
-module InnerType =
-    /// Parse from a JSON node.
-    let jsonParse (node: System.Text.Json.Nodes.JsonNode) : InnerType =
-        let Thing = node.["something"].AsValue().GetValue<string>()
-        { Thing = Thing }
-namespace UsePlugin
-
-/// Module containing JSON parsing methods for the JsonRecordType type
-[<RequireQualifiedAccess>]
-[<CompilationRepresentation(CompilationRepresentationFlags.ModuleSuffix)>]
-module JsonRecordType =
-    /// Parse from a JSON node.
-    let jsonParse (node: System.Text.Json.Nodes.JsonNode) : JsonRecordType =
-        let D = InnerType.jsonParse node.["d"]
-
-        let C =
-            node.["hi"].AsArray() |> Seq.map (fun elt -> elt.GetValue<int>()) |> List.ofSeq
-
-        let B = node.["b"].AsValue().GetValue<string>()
-        let A = node.["a"].AsValue().GetValue<int>()
-        { A = A; B = B; C = C; D = D }
-```
-
-You can optionally supply the boolean `true` to the attribute,
-which will cause Myriad to stamp out an extension method rather than a module with the same name as the type.
-This is useful if you want to reuse the type name as a module name yourself,
-or if you want to apply multiple source generators which each want to use the module name.
-
-### What's the point?
-
-`System.Text.Json`, in a `PublishAot` context, relies on C# source generators.
-The default reflection-heavy implementations have the necessary code trimmed away, and result in a runtime exception.
-But C# source generators [are entirely unsupported in F#](https://github.com/dotnet/fsharp/issues/14300).
-
-This Myriad generator expects you to use `System.Text.Json` to construct a `JsonNode`,
-and then the generator takes over to construct a strongly-typed object.
-
-### Limitations
-
-This source generator is enough for what I first wanted to use it for.
-However, there is *far* more that could be done.
-
-* Make it possible to give an exact format and cultural info in date and time parsing.
-* Make it possible to reject parsing if extra fields are present.
-* Generally support all the `System.Text.Json` attributes.
-
-For an example of using both `JsonParse` and `JsonSerialize` together with complex types, see [the type definitions](./ConsumePlugin/SerializationAndDeserialization.fs) and [tests](./WoofWare.Myriad.Plugins.Test/TestJsonSerialize/TestJsonSerde.fs).
-
-## `JsonSerialize`
-
-Takes records like this:
-```fsharp
-[<WoofWare.Myriad.Plugins.JsonSerialize true>]
-type InnerTypeWithBoth =
-    {
-        [<JsonPropertyName("it's-a-me")>]
-        Thing : string
-        ReadOnlyDict : IReadOnlyDictionary<string, Uri list>
-    }
-```
-
-and stamps out modules like this:
-```fsharp
-module InnerTypeWithBoth =
-    let toJsonNode (input : InnerTypeWithBoth) : System.Text.Json.Nodes.JsonNode =
-        let node = System.Text.Json.Nodes.JsonObject ()
-
-        do
-            node.Add (("it's-a-me"), System.Text.Json.Nodes.JsonValue.Create<string> input.Thing)
-
-            node.Add (
-                "ReadOnlyDict",
-                (fun field ->
-                    let ret = System.Text.Json.Nodes.JsonObject ()
-
-                    for (KeyValue (key, value)) in field do
-                        ret.Add (key.ToString (), System.Text.Json.Nodes.JsonValue.Create<Uri> value)
-
-                    ret
-                ) input.Map
-            )
-
-        node
-```
-
-As in `JsonParse`, you can optionally supply the boolean `true` to the attribute,
-which will cause Myriad to stamp out an extension method rather than a module with the same name as the type.
-
-The same limitations generally apply to `JsonSerialize` as do to `JsonParse`.
-
-For an example of using both `JsonParse` and `JsonSerialize` together with complex types, see [the type definitions](./ConsumePlugin/SerializationAndDeserialization.fs) and [tests](./WoofWare.Myriad.Plugins.Test/TestJsonSerialize/TestJsonSerde.fs).
-
-## `RemoveOptions`
-
-Takes a record like this:
-
-```fsharp
-type Foo =
-    {
-        A : int option
-        B : string
-        C : float list
-    }
-```
-
-and stamps out a record like this:
-
-```fsharp
-[<RequireQualifiedAccess>]
-module Foo =
-    type Short =
-        {
-            A : int
-            B : string
-            C : float list
-        }
-```
-
-### What's the point?
-
-The motivating example is argument parsing.
-An argument parser naturally wants to express "the user did not supply this, so I will provide a default".
-But it's not a very ergonomic experience for the programmer to deal with all these options,
-so this Myriad generator stamps out a type *without* any options,
-and also stamps out an appropriate constructor function.
-
-### Limitations
-
-This generator is *far* from where I want it, because I haven't really spent any time on it.
-
-* It really wants to be able to recurse into the types within the record, to strip options from them.
-* It needs some sort of attribute to mark a field as *not* receiving this treatment.
-* What do we do about discriminated unions?
-
-## `HttpClient`
-
-Takes a type like this:
-
-```fsharp
-[<WoofWare.Myriad.Plugins.HttpClient>]
-type IPureGymApi =
-    [<Get "v1/gyms/">]
-    abstract GetGyms : ?ct : CancellationToken -> Task<Gym list>
-
-    [<Get "v1/gyms/{gym_id}/attendance">]
-    abstract GetGymAttendance : [<Path "gym_id">] gymId : int * ?ct : CancellationToken -> Task<GymAttendance>
-
-    [<Get "v1/member">]
-    abstract GetMember : ?ct : CancellationToken -> Task<Member>
-
-    [<Get "v1/gyms/{gym_id}">]
-    abstract GetGym : [<Path "gym_id">] gymId : int * ?ct : CancellationToken -> Task<Gym>
-
-    [<Get "v1/member/activity">]
-    abstract GetMemberActivity : ?ct : CancellationToken -> Task<MemberActivityDto>
-
-    [<Get "v2/gymSessions/member">]
-    abstract GetSessions :
-        [<Query>] fromDate : DateTime * [<Query>] toDate : DateTime * ?ct : CancellationToken -> Task<Sessions>
-```
-
-and stamps out a type like this:
-
-```fsharp
-/// Module for constructing a REST client.
-[<CompilationRepresentation(CompilationRepresentationFlags.ModuleSuffix)>]
-[<RequireQualifiedAccess>]
-module PureGymApi =
-    /// Create a REST client.
-    let make (client : System.Net.Http.HttpClient) : IPureGymApi =
-        { new IPureGymApi with
-            member _.GetGyms (ct : CancellationToken option) =
-                async {
-                    let! ct = Async.CancellationToken
-
-                    let httpMessage =
-                        new System.Net.Http.HttpRequestMessage (
-                            Method = System.Net.Http.HttpMethod.Get,
-                            RequestUri = System.Uri (client.BaseAddress.ToString () + "v1/gyms/")
-                        )
-
-                    let! response = client.SendAsync (httpMessage, ct) |> Async.AwaitTask
-                    let response = response.EnsureSuccessStatusCode ()
-                    let! stream = response.Content.ReadAsStreamAsync ct |> Async.AwaitTask
-
-                    let! node =
-                        System.Text.Json.Nodes.JsonNode.ParseAsync (stream, cancellationToken = ct)
-                        |> Async.AwaitTask
-
-                    return node.AsArray () |> Seq.map (fun elt -> Gym.jsonParse elt) |> List.ofSeq
-                }
-                |> (fun a -> Async.StartAsTask (a, ?cancellationToken = ct))
-
-            // (more methods here)
-        }
-```
-
-### What's the point?
-
-The motivating example is again ahead-of-time compilation: we wish to avoid the reflection which RestEase does.
-
-### Limitations
-
-RestEase is complex, and handles a lot of different stuff.
-
-* If you set the `BaseAddress` on your input `HttpClient`, make sure to end with a trailing slash
-  on any trailing directories (so `"blah/foo/"` rather than `"blah/foo"`).
-  We combine URIs using `UriKind.Relative`, so without a trailing slash, the last component may be chopped off.
-* Parameters are serialised naively with `toJsonNode` as though the `JsonSerialize` generator were applied,
-  and you can't control the serialisation. You can't yet serialise e.g. a primitive type this way (other than `String`);
-  all body parameters must be types which have a suitable `toJsonNode : 'a -> JsonNode` method.
-* Deserialisation follows the same logic as the `JsonParse` generator,
-  and it generally assumes you're using types which `JsonParse` is applied to.
-* Headers are not yet supported.
-* Anonymous parameters are currently forbidden.
-
-There are also some design decisions:
-
-* Every function must take an optional `CancellationToken` (which is good practice anyway);
-  so arguments are forced to be tupled.
-
-## `GenerateMock`
-
-Takes a type like this:
-
-```fsharp
-[<GenerateMock>]
-type IPublicType =
-    abstract Mem1 : string * int -> string list
-    abstract Mem2 : string -> int
-```
-
-and stamps out a type like this:
-
-```fsharp
-/// Mock record type for an interface
-type internal PublicTypeMock =
-    {
-        Mem1 : string * int -> string list
-        Mem2 : string -> int
-    }
-
-    static member Empty : PublicTypeMock =
-        {
-            Mem1 = (fun x -> raise (System.NotImplementedException "Unimplemented mock function"))
-            Mem2 = (fun x -> raise (System.NotImplementedException "Unimplemented mock function"))
-        }
-
-    interface IPublicType with
-        member this.Mem1 (arg0, arg1) = this.Mem1 (arg0, arg1)
-        member this.Mem2 (arg0) = this.Mem2 (arg0)
-```
-
-### What's the point?
-
-Reflective mocking libraries like [Foq](https://github.com/fsprojects/Foq) in my experience are a rich source of flaky tests.
-The [Grug-brained developer](https://grugbrain.dev/) would prefer to do this without reflection, and this reduces the rate of strange one-in-ten-thousand "failed to generate IL" errors.
-But since F# does not let you partially update an interface definition, we instead stamp out a record,
-thereby allowing the programmer to use F#'s record-update syntax.
-
-### Limitations
-
-* We make the resulting record type at most internal (never public), since this is intended only to be used in tests.
-  You will therefore need an `AssemblyInfo.fs` file [like the one in WoofWare.Myriad's own tests](./ConsumePlugin/AssemblyInfo.fs).
-
-# Detailed examples
-
-See the tests.
-For example, [PureGymDto.fs](./ConsumePlugin/PureGymDto.fs) is a real-world set of DTOs.
-
-## How to use
-
-* In your `.fsproj` file, define a helper variable so that subsequent steps don't all have to be kept in sync:
-    ```xml
-    <PropertyGroup>
-      <WoofWareMyriadPluginVersion>1.3.5</WoofWareMyriadPluginVersion>
-    </PropertyGroup>
-    ```
-* Take a reference on `WoofWare.Myriad.Plugins`:
-    ```xml
-    <ItemGroup>
-        <PackageReference Include="WoofWare.Myriad.Plugins" Version="$(WoofWareMyriadPluginVersion)" />
-    </ItemGroup>
-    ```
-* Point Myriad to the DLL within the NuGet package which is the source of the plugins:
-    ```xml
-    <ItemGroup>
-      <MyriadSdkGenerator Include="$(NuGetPackageRoot)/woofware.myriad.plugins/$(WoofWareMyriadPluginVersion)/lib/net6.0/WoofWare.Myriad.Plugins.dll" />
-    </ItemGroup>
-    ```
-
-Now you are ready to start using the generators.
-For example, this specifies that Myriad is to use the contents of `Client.fs` to generate the file `GeneratedClient.fs`:
-
-```xml
-<ItemGroup>
-    <Compile Include="Client.fs" />
-    <Compile Include="GeneratedClient.fs">
-        <MyriadFile>Client.fs</MyriadFile>
-    </Compile>
-</ItemGroup>
-```
-
-### Myriad Gotchas
-
-* MsBuild doesn't always realise that it needs to invoke Myriad during rebuild.
-  You can always save a whitespace change to the source file (e.g. `Client.fs` above),
-  and MsBuild will then execute Myriad during the next build.
-* [Fantomas](https://github.com/fsprojects/fantomas), the F# source formatter which powers Myriad,
-  is customisable with [editorconfig](https://editorconfig.org/),
-  but it [does not easily expose](https://github.com/fsprojects/fantomas/issues/3031) this customisation
-  except through the standalone Fantomas client.
-  So Myriad's output is formatted without respect to any conventions which may hold in the rest of your repository.
-  You should probably add these files to your [fantomasignore](https://github.com/fsprojects/fantomas/blob/a999b77ca5a024fbc3409955faac797e29b39d27/docs/docs/end-users/IgnoreFiles.md)
-  if you use Fantomas to format your repo;
-  the alternative is to manually reformat every time Myriad changes the generated files.
+# WoofWare.Myriad.Plugins
+
+[![NuGet version](https://img.shields.io/nuget/v/WoofWare.Myriad.Plugins.svg?style=flat-square)](https://www.nuget.org/packages/WoofWare.Myriad.Plugins)
+[![GitHub Actions status](https://github.com/Smaug123/WoofWare.Myriad/actions/workflows/dotnet.yaml/badge.svg)](https://github.com/Smaug123/WoofWare.Myriad/actions?query=branch%3Amain)
+[![License file](https://img.shields.io/github/license/Smaug123/WoofWare.Myriad)](./LICENSE)
+
+![Project logo: the face of a cartoon Shiba Inu, staring with powerful cyborg eyes directly at the viewer, with a background of stylised plugs.](./WoofWare.Myriad.Plugins/logo.png)
+
+Some helpers in [Myriad](https://github.com/MoiraeSoftware/myriad/) which might be useful.
+
+These are currently somewhat experimental, and I personally am their primary customer.
+The `RemoveOptions` generator in particular is extremely half-baked.
+
+If you would like to ensure that your particular use-case remains unbroken, please do contribute tests to this repository.
+The `ConsumePlugin` assembly contains a number of invocations of these source generators,
+so you just need to add copies of your types to that assembly to ensure that I will at least notice if I break the build;
+and if you add tests to `WoofWare.Myriad.Plugins.Test` then I will also notice if I break the runtime semantics of the generated code.
+
+Currently implemented:
+
+* `JsonParse` (to stamp out `jsonParse : JsonNode -> 'T` methods);
+* `JsonSerialize` (to stamp out `toJsonNode : 'T -> JsonNode` methods);
+* `RemoveOptions` (to strip `option` modifiers from a type).
+* `HttpClient` (to stamp out a [RestEase](https://github.com/canton7/RestEase)-style HTTP client).
+* `GenerateMock` (to stamp out a record type corresponding to an interface).
+* `CreateCatamorphism` (to stamp out a non-stack-overflowing [catamorphism](https://fsharpforfunandprofit.com/posts/recursive-types-and-folds/) for a discriminated union).
+
+## `JsonParse`
+
+Takes records like this:
+
+```fsharp
+[<WoofWare.Myriad.Plugins.JsonParse>]
+type InnerType =
+    {
+        [<JsonPropertyName "something">]
+        Thing : string
+    }
+
+/// My whatnot
+[<WoofWare.Myriad.Plugins.JsonParse>]
+type JsonRecordType =
+    {
+        /// A thing!
+        A : int
+        /// Another thing!
+        B : string
+        [<System.Text.Json.Serialization.JsonPropertyName "hi">]
+        C : int list
+        D : InnerType
+    }
+
+```
+
+and stamps out parsing methods like this:
+
+```fsharp
+/// Module containing JSON parsing methods for the InnerType type
+[<RequireQualifiedAccess>]
+[<CompilationRepresentation(CompilationRepresentationFlags.ModuleSuffix)>]
+module InnerType =
+    /// Parse from a JSON node.
+    let jsonParse (node: System.Text.Json.Nodes.JsonNode) : InnerType =
+        let Thing = node.["something"].AsValue().GetValue<string>()
+        { Thing = Thing }
+namespace UsePlugin
+
+/// Module containing JSON parsing methods for the JsonRecordType type
+[<RequireQualifiedAccess>]
+[<CompilationRepresentation(CompilationRepresentationFlags.ModuleSuffix)>]
+module JsonRecordType =
+    /// Parse from a JSON node.
+    let jsonParse (node: System.Text.Json.Nodes.JsonNode) : JsonRecordType =
+        let D = InnerType.jsonParse node.["d"]
+
+        let C =
+            node.["hi"].AsArray() |> Seq.map (fun elt -> elt.GetValue<int>()) |> List.ofSeq
+
+        let B = node.["b"].AsValue().GetValue<string>()
+        let A = node.["a"].AsValue().GetValue<int>()
+        { A = A; B = B; C = C; D = D }
+```
+
+You can optionally supply the boolean `true` to the attribute,
+which will cause Myriad to stamp out an extension method rather than a module with the same name as the type.
+This is useful if you want to reuse the type name as a module name yourself,
+or if you want to apply multiple source generators which each want to use the module name.
+
+### What's the point?
+
+`System.Text.Json`, in a `PublishAot` context, relies on C# source generators.
+The default reflection-heavy implementations have the necessary code trimmed away, and result in a runtime exception.
+But C# source generators [are entirely unsupported in F#](https://github.com/dotnet/fsharp/issues/14300).
+
+This Myriad generator expects you to use `System.Text.Json` to construct a `JsonNode`,
+and then the generator takes over to construct a strongly-typed object.
+
+### Limitations
+
+This source generator is enough for what I first wanted to use it for.
+However, there is *far* more that could be done.
+
+* Make it possible to give an exact format and cultural info in date and time parsing.
+* Make it possible to reject parsing if extra fields are present.
+* Generally support all the `System.Text.Json` attributes.
+
+For an example of using both `JsonParse` and `JsonSerialize` together with complex types, see [the type definitions](./ConsumePlugin/SerializationAndDeserialization.fs) and [tests](./WoofWare.Myriad.Plugins.Test/TestJsonSerialize/TestJsonSerde.fs).
+
+## `JsonSerialize`
+
+Takes records like this:
+```fsharp
+[<WoofWare.Myriad.Plugins.JsonSerialize true>]
+type InnerTypeWithBoth =
+    {
+        [<JsonPropertyName("it's-a-me")>]
+        Thing : string
+        ReadOnlyDict : IReadOnlyDictionary<string, Uri list>
+    }
+```
+
+and stamps out modules like this:
+```fsharp
+module InnerTypeWithBoth =
+    let toJsonNode (input : InnerTypeWithBoth) : System.Text.Json.Nodes.JsonNode =
+        let node = System.Text.Json.Nodes.JsonObject ()
+
+        do
+            node.Add (("it's-a-me"), System.Text.Json.Nodes.JsonValue.Create<string> input.Thing)
+
+            node.Add (
+                "ReadOnlyDict",
+                (fun field ->
+                    let ret = System.Text.Json.Nodes.JsonObject ()
+
+                    for (KeyValue (key, value)) in field do
+                        ret.Add (key.ToString (), System.Text.Json.Nodes.JsonValue.Create<Uri> value)
+
+                    ret
+                ) input.Map
+            )
+
+        node
+```
+
+As in `JsonParse`, you can optionally supply the boolean `true` to the attribute,
+which will cause Myriad to stamp out an extension method rather than a module with the same name as the type.
+
+The same limitations generally apply to `JsonSerialize` as do to `JsonParse`.
+
+For an example of using both `JsonParse` and `JsonSerialize` together with complex types, see [the type definitions](./ConsumePlugin/SerializationAndDeserialization.fs) and [tests](./WoofWare.Myriad.Plugins.Test/TestJsonSerialize/TestJsonSerde.fs).
+
+## `RemoveOptions`
+
+Takes a record like this:
+
+```fsharp
+type Foo =
+    {
+        A : int option
+        B : string
+        C : float list
+    }
+```
+
+and stamps out a record like this:
+
+```fsharp
+[<RequireQualifiedAccess>]
+module Foo =
+    type Short =
+        {
+            A : int
+            B : string
+            C : float list
+        }
+```
+
+### What's the point?
+
+The motivating example is argument parsing.
+An argument parser naturally wants to express "the user did not supply this, so I will provide a default".
+But it's not a very ergonomic experience for the programmer to deal with all these options,
+so this Myriad generator stamps out a type *without* any options,
+and also stamps out an appropriate constructor function.
+
+### Limitations
+
+This generator is *far* from where I want it, because I haven't really spent any time on it.
+
+* It really wants to be able to recurse into the types within the record, to strip options from them.
+* It needs some sort of attribute to mark a field as *not* receiving this treatment.
+* What do we do about discriminated unions?
+
+## `HttpClient`
+
+Takes a type like this:
+
+```fsharp
+[<WoofWare.Myriad.Plugins.HttpClient>]
+type IPureGymApi =
+    [<Get "v1/gyms/">]
+    abstract GetGyms : ?ct : CancellationToken -> Task<Gym list>
+
+    [<Get "v1/gyms/{gym_id}/attendance">]
+    abstract GetGymAttendance : [<Path "gym_id">] gymId : int * ?ct : CancellationToken -> Task<GymAttendance>
+
+    [<Get "v1/member">]
+    abstract GetMember : ?ct : CancellationToken -> Task<Member>
+
+    [<Get "v1/gyms/{gym_id}">]
+    abstract GetGym : [<Path "gym_id">] gymId : int * ?ct : CancellationToken -> Task<Gym>
+
+    [<Get "v1/member/activity">]
+    abstract GetMemberActivity : ?ct : CancellationToken -> Task<MemberActivityDto>
+
+    [<Get "v2/gymSessions/member">]
+    abstract GetSessions :
+        [<Query>] fromDate : DateTime * [<Query>] toDate : DateTime * ?ct : CancellationToken -> Task<Sessions>
+```
+
+and stamps out a type like this:
+
+```fsharp
+/// Module for constructing a REST client.
+[<CompilationRepresentation(CompilationRepresentationFlags.ModuleSuffix)>]
+[<RequireQualifiedAccess>]
+module PureGymApi =
+    /// Create a REST client.
+    let make (client : System.Net.Http.HttpClient) : IPureGymApi =
+        { new IPureGymApi with
+            member _.GetGyms (ct : CancellationToken option) =
+                async {
+                    let! ct = Async.CancellationToken
+
+                    let httpMessage =
+                        new System.Net.Http.HttpRequestMessage (
+                            Method = System.Net.Http.HttpMethod.Get,
+                            RequestUri = System.Uri (client.BaseAddress.ToString () + "v1/gyms/")
+                        )
+
+                    let! response = client.SendAsync (httpMessage, ct) |> Async.AwaitTask
+                    let response = response.EnsureSuccessStatusCode ()
+                    let! stream = response.Content.ReadAsStreamAsync ct |> Async.AwaitTask
+
+                    let! node =
+                        System.Text.Json.Nodes.JsonNode.ParseAsync (stream, cancellationToken = ct)
+                        |> Async.AwaitTask
+
+                    return node.AsArray () |> Seq.map (fun elt -> Gym.jsonParse elt) |> List.ofSeq
+                }
+                |> (fun a -> Async.StartAsTask (a, ?cancellationToken = ct))
+
+            // (more methods here)
+        }
+```
+
+### What's the point?
+
+The motivating example is again ahead-of-time compilation: we wish to avoid the reflection which RestEase does.
+
+### Features
+
+* Variable and constant header values are supported:
+  see [the definition of `IApiWithHeaders`](./ConsumePlugin/RestApiExample.fs).
+
+### Limitations
+
+RestEase is complex, and handles a lot of different stuff.
+
+* If you set the `BaseAddress` on your input `HttpClient`, make sure to end with a trailing slash
+  on any trailing directories (so `"blah/foo/"` rather than `"blah/foo"`).
+  We combine URIs using `UriKind.Relative`, so without a trailing slash, the last component may be chopped off.
+* Parameters are serialised naively with `toJsonNode` as though the `JsonSerialize` generator were applied,
+  and you can't control the serialisation. You can't yet serialise e.g. a primitive type this way (other than `String`);
+  all body parameters must be types which have a suitable `toJsonNode : 'a -> JsonNode` method.
+* Deserialisation follows the same logic as the `JsonParse` generator,
+  and it generally assumes you're using types which `JsonParse` is applied to.
+* Anonymous parameters are currently forbidden.
+
+There are also some design decisions:
+
+* Every function must take an optional `CancellationToken` (which is good practice anyway);
+  so arguments are forced to be tupled.
+* The `[<Optional>]` attribute is not supported and will probably not be supported, because I consider it to be cursed.
+
+## `GenerateMock`
+
+Takes a type like this:
+
+```fsharp
+[<GenerateMock>]
+type IPublicType =
+    abstract Mem1 : string * int -> string list
+    abstract Mem2 : string -> int
+```
+
+and stamps out a type like this:
+
+```fsharp
+/// Mock record type for an interface
+type internal PublicTypeMock =
+    {
+        Mem1 : string * int -> string list
+        Mem2 : string -> int
+    }
+
+    static member Empty : PublicTypeMock =
+        {
+            Mem1 = (fun x -> raise (System.NotImplementedException "Unimplemented mock function"))
+            Mem2 = (fun x -> raise (System.NotImplementedException "Unimplemented mock function"))
+        }
+
+    interface IPublicType with
+        member this.Mem1 (arg0, arg1) = this.Mem1 (arg0, arg1)
+        member this.Mem2 (arg0) = this.Mem2 (arg0)
+```
+
+### What's the point?
+
+Reflective mocking libraries like [Foq](https://github.com/fsprojects/Foq) in my experience are a rich source of flaky tests.
+The [Grug-brained developer](https://grugbrain.dev/) would prefer to do this without reflection, and this reduces the rate of strange one-in-ten-thousand "failed to generate IL" errors.
+But since F# does not let you partially update an interface definition, we instead stamp out a record,
+thereby allowing the programmer to use F#'s record-update syntax.
+
+### Features
+
+* You may supply an `isInternal : bool` argument to the attribute. By default, we make the resulting record type at most internal (never public), since this is intended only to be used in tests; but you can instead make it public with `[<GenerateMock false>]`.
+
+## `CreateCatamorphism`
+
+Takes a collection of mutually recursive discriminated unions:
+
+```fsharp
+[<CreateCatamorphism "MyCata">]
+type Expr =
+    | Const of Const
+    | Pair of Expr * Expr * PairOpKind
+    | Sequential of Expr list
+    | Builder of Expr * ExprBuilder
+
+and ExprBuilder =
+    | Child of ExprBuilder
+    | Parent of Expr
+```
+
+and stamps out a type like this:
+```fsharp
+type ExprCata<'Expr, 'ExprBuilder> =
+    abstract Const : Const -> 'Expr
+    abstract Pair : 'Expr -> 'Expr -> PairOpKind -> 'Expr
+    abstract Sequential : 'Expr list -> 'Expr
+    abstract Builder : 'Expr -> 'ExprBuilder -> 'Expr
+
+type ExprBuilderCata<'Expr, 'ExprBuilder> =
+    abstract Child : 'ExprBuilder -> 'ExprBuilder
+    abstract Parent : 'Expr -> 'ExprBuilder
+
+type MyCata<'Expr, 'ExprBuilder> =
+    {
+        Expr : ExprCata<'Expr, 'ExprBuilder>
+        ExprBuilder : ExprBuilderCata<'Expr, 'ExprBuilder>
+    }
+
+[<RequireQualifiedAccess>]
+module ExprCata =
+    let runExpr (cata : MyCata<'ExprRet, 'ExprBuilderRet>) (x : Expr) : 'ExprRet =
+        failwith "this is implemented"
+
+    let runExprBuilder (cata : MyCata<'ExprRet, 'ExprBuilderRet>) (x : ExprBuilder) : 'ExprBuilderRet =
+        failwith "this is implemented"
+```
+
+### What's the point?
+Recursing over a tree is not easy to get right, especially if you want to avoid stack overflows.
+Instead of writing the recursion many times, it's better to do it once,
+and then each time you only plug in what you want to do.
+
+### Features
+
+* Mutually recursive DUs are supported (as in the example above).
+  Every DU in a recursive `type Foo... and Bar...` knot will be given an appropriate cata, as long as any one of those DUs has the `[<CreateCatamorphism>]` attribute.
+* There is *limited* support for records and for lists.
+* There is *extremely brittle* support for generics in the DUs you are cata'ing over.
+  It is based on the names of the generic parameters, so you must ensure that generic parameters with the same name have the same meaning across the various cases in your recursive knot of DUs.
+  (If you overstep the bounds of what this generator can do, you will get compile-time errors, e.g. with generics being constrained to each other's values.)
+  See the [List tests](./WoofWare.Myriad.Plugins.Test/TestCataGenerator/TestMyList2.fs) for an example, where we re-implement `FSharpList<'a>`.
+
+### Limitations
+
+**I am not at all convinced of the correctness of this generator**, and I know it is very incomplete (in the sense that there are many possible DUs you could write for which the generator will bail out).
+I *strongly* recommend implementing the identity catamorphism for your type and using property-based tests ([as I do](./WoofWare.Myriad.Plugins.Test/TestCataGenerator/TestDirectory.fs)) to assert that the correct thing happens.
+Feel free to raise GitHub issues with code I can copy-paste to reproduce a case where the wrong thing happens (though I can't promise to look at them).
+
+* This is a particularly half-baked generator which has so far seen no real-world use.
+  It likely has a bunch of [80/20](https://en.wikipedia.org/wiki/Pareto_principle) low-hanging fruit remaining, but it also likely has impossible problems to solve which I don't know about yet.
+* Only a very few kinds of DU field are currently implemented.
+  For example, this generator can't see through an interface (e.g. the kind of interface one would use to implement the [crate pattern](https://www.patrickstevens.co.uk/posts/2021-10-19-crates/) to represent a [GADT](https://en.wikipedia.org/wiki/Generalized_algebraic_data_type)),
+  so the generated cata will simply grant you access to the interface (rather than attempting to descend into it to discover recursive references).
+  You can't nest lists deeply. All sorts of other cases are unaddressed.
+* This generator does not try to solve the "exponential diamond dependency" problem.
+  If you have a case of the form `type Expr = | Branch of Expr * Expr`, the cata will walk into both `Expr`s separately.
+  If the `Expr`s happen to be equal, the cata will nevertheless traverse them individually (that is, it will traverse the same `Expr` twice).
+  Your type may represent a [DAG](https://en.wikipedia.org/wiki/Directed_acyclic_graph), but we will always effectively expand it into a tree of paths and operate on each of the exponentially-many paths.
+
+# Detailed examples
+
+See the tests.
+For example, [PureGymDto.fs](./ConsumePlugin/PureGymDto.fs) is a real-world set of DTOs.
+
+## How to use
+
+* In your `.fsproj` file, define a helper variable so that subsequent steps don't all have to be kept in sync:
+    ```xml
+    <PropertyGroup>
+      <WoofWareMyriadPluginVersion>2.0.1</WoofWareMyriadPluginVersion>
+    </PropertyGroup>
+    ```
+* Take a reference on `WoofWare.Myriad.Plugins.Attributes` (which has no other dependencies), to obtain access to the attributes which the generator will recognise:
+    ```xml
+    <ItemGroup>
+        <PackageReference Include="WoofWare.Myriad.Plugins.Attributes" Version="2.0.2" />
+    </ItemGroup>
+    ```
+* Take a reference (with private assets, to prevent these from propagating to your own assembly) on `WoofWare.Myriad.Plugins`, to obtain the plugins which Myriad will run, and on `Myriad.Sdk`, to obtain the Myriad binary itself:
+    ```xml
+    <ItemGroup>
+        <PackageReference Include="WoofWare.Myriad.Plugins" Version="$(WoofWareMyriadPluginVersion)" PrivateAssets="all" />
+        <PackageReference Include="Myriad.Sdk" Version="0.8.3" PrivateAssets="all" />
+    </ItemGroup>
+    ```
+* Point Myriad to the DLL within the NuGet package which is the source of the plugins:
+    ```xml
+    <ItemGroup>
+      <MyriadSdkGenerator Include="$(NuGetPackageRoot)/woofware.myriad.plugins/$(WoofWareMyriadPluginVersion)/lib/net6.0/WoofWare.Myriad.Plugins.dll" />
+    </ItemGroup>
+    ```
+
+Now you are ready to start using the generators.
+For example, this specifies that Myriad is to use the contents of `Client.fs` to generate the file `GeneratedClient.fs`:
+
+```xml
+<ItemGroup>
+    <Compile Include="Client.fs" />
+    <Compile Include="GeneratedClient.fs">
+        <MyriadFile>Client.fs</MyriadFile>
+    </Compile>
+</ItemGroup>
+```
+
+### Myriad Gotchas
+
+* MsBuild doesn't always realise that it needs to invoke Myriad during rebuild.
+  You can always save a whitespace change to the source file (e.g. `Client.fs` above),
+  and MsBuild will then execute Myriad during the next build.
+* [Fantomas](https://github.com/fsprojects/fantomas), the F# source formatter which powers Myriad,
+  is customisable with [editorconfig](https://editorconfig.org/),
+  but it [does not easily expose](https://github.com/fsprojects/fantomas/issues/3031) this customisation
+  except through the standalone Fantomas client.
+  So Myriad's output is formatted without respect to any conventions which may hold in the rest of your repository.
+  You should probably add these files to your [fantomasignore](https://github.com/fsprojects/fantomas/blob/a999b77ca5a024fbc3409955faac797e29b39d27/docs/docs/end-users/IgnoreFiles.md)
+  if you use Fantomas to format your repo;
+  the alternative is to manually reformat every time Myriad changes the generated files.

WoofWare.Myriad.Plugins.Attributes/Attributes.fs

@@ -0,0 +1,72 @@
+namespace WoofWare.Myriad.Plugins
+
+open System
+
+/// Attribute indicating a record type to which the "Remove Options" Myriad
+/// generator should apply during build.
+/// The purpose of this generator is to strip the `option` modifier from types.
+type RemoveOptionsAttribute () =
+    inherit Attribute ()
+
+/// Attribute indicating an interface type for which the "Generate Mock" Myriad
+/// generator should apply during build.
+/// This generator creates a record which implements the interface,
+/// but where each method is represented as a record field, so you can use
+/// record update syntax to easily specify partially-implemented mock objects.
+/// You may optionally specify `isInternal = false` to get a mock with the public visibility modifier.
+type GenerateMockAttribute (isInternal : bool) =
+    inherit Attribute ()
+    /// The default value of `isInternal`, the optional argument to the GenerateMockAttribute constructor.
+    static member DefaultIsInternal = true
+
+    /// Shorthand for the "isExtensionMethod = false" constructor; see documentation there for details.
+    new () = GenerateMockAttribute GenerateMockAttribute.DefaultIsInternal
+
+/// Attribute indicating a record type to which the "Add JSON serializer" Myriad
+/// generator should apply during build.
+/// The purpose of this generator is to create methods (possibly extension methods) of the form
+/// `{TypeName}.toJsonNode : {TypeName} -> System.Text.Json.Nodes.JsonNode`.
+///
+/// If you supply isExtensionMethod = true, you will get extension methods.
+/// These can only be consumed from F#, but the benefit is that they don't use up the module name
+/// (since by default we create a module called "{TypeName}").
+type JsonSerializeAttribute (isExtensionMethod : bool) =
+    inherit Attribute ()
+
+    /// The default value of `isExtensionMethod`, the optional argument to the JsonSerializeAttribute constructor.
+    static member DefaultIsExtensionMethod = false
+
+    /// Shorthand for the "isExtensionMethod = false" constructor; see documentation there for details.
+    new () = JsonSerializeAttribute JsonSerializeAttribute.DefaultIsExtensionMethod
+
+/// Attribute indicating a record type to which the "Add JSON parse" Myriad
+/// generator should apply during build.
+/// The purpose of this generator is to create methods (possibly extension methods) of the form
+/// `{TypeName}.jsonParse : System.Text.Json.Nodes.JsonNode -> {TypeName}`.
+///
+/// If you supply isExtensionMethod = true, you will get extension methods.
+/// These can only be consumed from F#, but the benefit is that they don't use up the module name
+/// (since by default we create a module called "{TypeName}").
+type JsonParseAttribute (isExtensionMethod : bool) =
+    inherit Attribute ()
+
+    /// The default value of `isExtensionMethod`, the optional argument to the JsonParseAttribute constructor.
+    static member DefaultIsExtensionMethod = false
+
+    /// Shorthand for the "isExtensionMethod = false" constructor; see documentation there for details.
+    new () = JsonParseAttribute JsonParseAttribute.DefaultIsExtensionMethod
+
+/// Attribute indicating a record type to which the "create HTTP client" Myriad
+/// generator should apply during build.
+/// This generator is intended to replicate much of the functionality of RestEase,
+/// i.e. to stamp out HTTP REST clients from interfaces defining the API.
+type HttpClientAttribute () =
+    inherit Attribute ()
+
+/// Attribute indicating a DU type to which the "create catamorphism" Myriad
+/// generator should apply during build.
+/// Supply the `typeName` for the name of the record type we will generate, which contains
+/// all the catas required; for example, "MyThing" would generate:
+/// type MyThing<'a, 'b> = { Du1 : Du1Cata<'a, 'b> ; Du2 : Du2Cata<'a, 'b> }.
+type CreateCatamorphismAttribute (typeName : string) =
+    inherit Attribute ()

WoofWare.Myriad.Plugins.Attributes/RestEase.fs

@@ -0,0 +1,63 @@
+namespace WoofWare.Myriad.Plugins
+
+open System
+
+/// Module containing duplicates of the supported RestEase attributes, in case you don't want
+/// to take a dependency on RestEase.
+[<RequireQualifiedAccess>]
+module RestEase =
+    /// Indicates that a method represents an HTTP Get query to the specified endpoint.
+    type GetAttribute (path : string) =
+        inherit Attribute ()
+
+    /// Indicates that a method represents an HTTP Post query to the specified endpoint.
+    type PostAttribute (path : string) =
+        inherit Attribute ()
+
+    /// Indicates that a method represents an HTTP Delete query to the specified endpoint.
+    type DeleteAttribute (path : string) =
+        inherit Attribute ()
+
+    /// Indicates that a method represents an HTTP Head query to the specified endpoint.
+    type HeadAttribute (path : string) =
+        inherit Attribute ()
+
+    /// Indicates that a method represents an HTTP Options query to the specified endpoint.
+    type OptionsAttribute (path : string) =
+        inherit Attribute ()
+
+    /// Indicates that a method represents an HTTP Put query to the specified endpoint.
+    type PutAttribute (path : string) =
+        inherit Attribute ()
+
+    /// Indicates that a method represents an HTTP Patch query to the specified endpoint.
+    type PatchAttribute (path : string) =
+        inherit Attribute ()
+
+    /// Indicates that a method represents an HTTP Trace query to the specified endpoint.
+    type TraceAttribute (path : string) =
+        inherit Attribute ()
+
+    /// Indicates that this argument to a method is interpolated into the HTTP request at runtime
+    /// by setting a query parameter (with the given name) to the value of the annotated argument.
+    type QueryAttribute (paramName : string) =
+        inherit Attribute ()
+
+    /// Indicates that this interface represents a REST client which accesses an API whose paths are
+    /// all relative to the given address.
+    type BaseAddressAttribute (addr : string) =
+        inherit Attribute ()
+
+    /// Indicates that this interface member causes the interface to set a header with the given name,
+    /// whose value is obtained whenever required by a fresh call to the interface member.
+    type HeaderAttribute (header : string, value : string option) =
+        inherit Attribute ()
+        new (header : string) = HeaderAttribute (header, None)
+        new (header : string, value : string) = HeaderAttribute (header, Some value)
+
+    /// Indicates that this argument to a method is interpolated into the request path at runtime
+    /// by writing it into the templated string that specifies the HTTP query e.g. in the `[<Get "/foo/{template}">]`.
+    type PathAttribute (path : string option) =
+        inherit Attribute ()
+        new (path : string) = PathAttribute (Some path)
+        new () = PathAttribute None

WoofWare.Myriad.Plugins.Attributes/SurfaceBaseline.txt

@@ -0,0 +1,50 @@
+WoofWare.Myriad.Plugins.CreateCatamorphismAttribute inherit System.Attribute
+WoofWare.Myriad.Plugins.CreateCatamorphismAttribute..ctor [constructor]: string
+WoofWare.Myriad.Plugins.GenerateMockAttribute inherit System.Attribute
+WoofWare.Myriad.Plugins.GenerateMockAttribute..ctor [constructor]: bool
+WoofWare.Myriad.Plugins.GenerateMockAttribute..ctor [constructor]: unit
+WoofWare.Myriad.Plugins.GenerateMockAttribute.DefaultIsInternal [static property]: [read-only] bool
+WoofWare.Myriad.Plugins.GenerateMockAttribute.get_DefaultIsInternal [static method]: unit -> bool
+WoofWare.Myriad.Plugins.HttpClientAttribute inherit System.Attribute
+WoofWare.Myriad.Plugins.HttpClientAttribute..ctor [constructor]: unit
+WoofWare.Myriad.Plugins.JsonParseAttribute inherit System.Attribute
+WoofWare.Myriad.Plugins.JsonParseAttribute..ctor [constructor]: bool
+WoofWare.Myriad.Plugins.JsonParseAttribute..ctor [constructor]: unit
+WoofWare.Myriad.Plugins.JsonParseAttribute.DefaultIsExtensionMethod [static property]: [read-only] bool
+WoofWare.Myriad.Plugins.JsonParseAttribute.get_DefaultIsExtensionMethod [static method]: unit -> bool
+WoofWare.Myriad.Plugins.JsonSerializeAttribute inherit System.Attribute
+WoofWare.Myriad.Plugins.JsonSerializeAttribute..ctor [constructor]: bool
+WoofWare.Myriad.Plugins.JsonSerializeAttribute..ctor [constructor]: unit
+WoofWare.Myriad.Plugins.JsonSerializeAttribute.DefaultIsExtensionMethod [static property]: [read-only] bool
+WoofWare.Myriad.Plugins.JsonSerializeAttribute.get_DefaultIsExtensionMethod [static method]: unit -> bool
+WoofWare.Myriad.Plugins.RemoveOptionsAttribute inherit System.Attribute
+WoofWare.Myriad.Plugins.RemoveOptionsAttribute..ctor [constructor]: unit
+WoofWare.Myriad.Plugins.RestEase inherit obj
+WoofWare.Myriad.Plugins.RestEase+BaseAddressAttribute inherit System.Attribute
+WoofWare.Myriad.Plugins.RestEase+BaseAddressAttribute..ctor [constructor]: string
+WoofWare.Myriad.Plugins.RestEase+DeleteAttribute inherit System.Attribute
+WoofWare.Myriad.Plugins.RestEase+DeleteAttribute..ctor [constructor]: string
+WoofWare.Myriad.Plugins.RestEase+GetAttribute inherit System.Attribute
+WoofWare.Myriad.Plugins.RestEase+GetAttribute..ctor [constructor]: string
+WoofWare.Myriad.Plugins.RestEase+HeadAttribute inherit System.Attribute
+WoofWare.Myriad.Plugins.RestEase+HeadAttribute..ctor [constructor]: string
+WoofWare.Myriad.Plugins.RestEase+HeaderAttribute inherit System.Attribute
+WoofWare.Myriad.Plugins.RestEase+HeaderAttribute..ctor [constructor]: (string, string option)
+WoofWare.Myriad.Plugins.RestEase+HeaderAttribute..ctor [constructor]: (string, string)
+WoofWare.Myriad.Plugins.RestEase+HeaderAttribute..ctor [constructor]: string
+WoofWare.Myriad.Plugins.RestEase+OptionsAttribute inherit System.Attribute
+WoofWare.Myriad.Plugins.RestEase+OptionsAttribute..ctor [constructor]: string
+WoofWare.Myriad.Plugins.RestEase+PatchAttribute inherit System.Attribute
+WoofWare.Myriad.Plugins.RestEase+PatchAttribute..ctor [constructor]: string
+WoofWare.Myriad.Plugins.RestEase+PathAttribute inherit System.Attribute
+WoofWare.Myriad.Plugins.RestEase+PathAttribute..ctor [constructor]: string
+WoofWare.Myriad.Plugins.RestEase+PathAttribute..ctor [constructor]: string option
+WoofWare.Myriad.Plugins.RestEase+PathAttribute..ctor [constructor]: unit
+WoofWare.Myriad.Plugins.RestEase+PostAttribute inherit System.Attribute
+WoofWare.Myriad.Plugins.RestEase+PostAttribute..ctor [constructor]: string
+WoofWare.Myriad.Plugins.RestEase+PutAttribute inherit System.Attribute
+WoofWare.Myriad.Plugins.RestEase+PutAttribute..ctor [constructor]: string
+WoofWare.Myriad.Plugins.RestEase+QueryAttribute inherit System.Attribute
+WoofWare.Myriad.Plugins.RestEase+QueryAttribute..ctor [constructor]: string
+WoofWare.Myriad.Plugins.RestEase+TraceAttribute inherit System.Attribute
+WoofWare.Myriad.Plugins.RestEase+TraceAttribute..ctor [constructor]: string

WoofWare.Myriad.Plugins.Attributes/Test/TestSurface.fs

@@ -0,0 +1,24 @@
+namespace WoofWare.Myriad.Plugins.Attributes.Test
+
+open NUnit.Framework
+open WoofWare.Myriad.Plugins
+open ApiSurface
+
+[<TestFixture>]
+module TestSurface =
+    let assembly = typeof<RemoveOptionsAttribute>.Assembly
+
+    [<Test>]
+    let ``Ensure API surface has not been modified`` () = ApiSurface.assertIdentical assembly
+
+    [<Test>]
+    let ``Check version against remote`` () =
+        MonotonicVersion.validate assembly "WoofWare.Myriad.Plugins.Attributes"
+
+    [<Test ; Explicit>]
+    let ``Update API surface`` () =
+        ApiSurface.writeAssemblyBaseline assembly
+
+    [<Test>]
+    let ``Ensure public API is fully documented`` () =
+        DocCoverage.assertFullyDocumented assembly

WoofWare.Myriad.Plugins.Attributes/Test/WoofWare.Myriad.Plugins.Attributes.Test.fsproj

@@ -0,0 +1,25 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+    <PropertyGroup>
+        <TargetFramework>net8.0</TargetFramework>
+
+        <IsPackable>false</IsPackable>
+        <IsTestProject>true</IsTestProject>
+    </PropertyGroup>
+
+    <ItemGroup>
+        <Compile Include="TestSurface.fs" />
+    </ItemGroup>
+
+    <ItemGroup>
+        <PackageReference Include="ApiSurface" Version="4.0.39" />
+        <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.9.0"/>
+        <PackageReference Include="NUnit" Version="4.1.0"/>
+        <PackageReference Include="NUnit3TestAdapter" Version="4.5.0"/>
+    </ItemGroup>
+
+    <ItemGroup>
+      <ProjectReference Include="..\WoofWare.Myriad.Plugins.Attributes.fsproj" />
+    </ItemGroup>
+
+</Project>

WoofWare.Myriad.Plugins.Attributes/WoofWare.Myriad.Plugins.Attributes.fsproj

@@ -0,0 +1,39 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>netstandard2.0</TargetFramework>
+    <GenerateDocumentationFile>true</GenerateDocumentationFile>
+    <Authors>Patrick Stevens</Authors>
+    <Copyright>Copyright (c) Patrick Stevens 2024</Copyright>
+    <Description>Attributes to accompany the WoofWare.Myriad.Plugins source generator, so that you need take no runtime dependencies to use them.</Description>
+    <RepositoryType>git</RepositoryType>
+    <RepositoryUrl>https://github.com/Smaug123/WoofWare.Myriad</RepositoryUrl>
+    <PackageLicenseExpression>MIT</PackageLicenseExpression>
+    <PackageReadmeFile>README.md</PackageReadmeFile>
+    <PackageTags>myriad;fsharp;source-generator;source-gen;json</PackageTags>
+    <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
+    <WarnOn>FS3559</WarnOn>
+    <PackageId>WoofWare.Myriad.Plugins.Attributes</PackageId>
+    <PackageIcon>logo.png</PackageIcon>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <Compile Include="Attributes.fs"/>
+    <Compile Include="RestEase.fs" />
+    <EmbeddedResource Include="version.json"/>
+    <EmbeddedResource Include="SurfaceBaseline.txt"/>
+    <None Include="..\README.md">
+      <Pack>True</Pack>
+      <PackagePath>\</PackagePath>
+    </None>
+    <None Include="../WoofWare.Myriad.Plugins/logo.png">
+      <Pack>True</Pack>
+      <PackagePath>\</PackagePath>
+    </None>
+  </ItemGroup>
+
+  <ItemGroup>
+    <PackageReference Update="FSharp.Core" Version="4.3.4"/>
+  </ItemGroup>
+
+</Project>

WoofWare.Myriad.Plugins.Attributes/version.json

@@ -0,0 +1,7 @@
+{
+  "version": "3.0",
+  "publicReleaseRefSpec": [
+    "^refs/heads/main$"
+  ],
+  "pathFilters": null
+}

WoofWare.Myriad.Plugins.Test/TestCataGenerator/TestCataGenerator.fs

@@ -0,0 +1,47 @@
+namespace WoofWare.Myriad.Plugins.Test
+
+open System.Threading
+open NUnit.Framework
+open FsUnitTyped
+open ConsumePlugin
+open FsCheck
+
+[<TestFixture>]
+module TestCataGenerator =
+    let idCata<'a, 'b> : TreeCata<'a, 'b, _, _> =
+        {
+            Tree =
+                { new TreeCataCase<_, _, _, _> with
+                    member _.Const x y = Const (x, y)
+                    member _.Pair x y z = Pair (x, y, z)
+                    member _.Sequential xs = Sequential xs
+                    member _.Builder x b = Builder (x, b)
+                }
+            TreeBuilder =
+                { new TreeBuilderCataCase<_, _, _, _> with
+                    member _.Child x = Child x
+                    member _.Parent x = Parent x
+                }
+        }
+
+    [<Test>]
+    let ``Example`` () =
+        let x =
+            Tree.Pair (Tree.Const (Const.Verbatim 0, "hi"), Tree.Const (Const.String "", "bye"), PairOpKind.ThenDoSeq)
+
+        TreeCata.runTree idCata x |> shouldEqual x
+
+
+    [<Test>]
+    let ``Cata works`` () =
+        let builderCases = ref 0
+
+        let property (x : Tree<int, string>) =
+            match x with
+            | Tree.Builder _ -> Interlocked.Increment builderCases |> ignore
+            | _ -> ()
+
+            TreeCata.runTree idCata x = x
+
+        Check.QuickThrowOnFailure property
+        builderCases.Value |> shouldBeGreaterThan 10

WoofWare.Myriad.Plugins.Test/TestCataGenerator/TestDirectory.fs

@@ -0,0 +1,37 @@
+namespace WoofWare.Myriad.Plugins.Test
+
+open NUnit.Framework
+open ConsumePlugin
+open FsCheck
+
+[<TestFixture>]
+module TestDirectory =
+    let idCata : FileSystemCata<_> =
+        {
+            FileSystemItem =
+                { new FileSystemItemCataCase<_> with
+                    member _.File file = FileSystemItem.File file
+
+                    member _.Directory name dirSize results =
+                        FileSystemItem.Directory
+                            {
+                                Name = name
+                                DirSize = dirSize
+                                Contents = results
+                            }
+                }
+
+        }
+
+    // Note: this file is preserved as an example of writing an identity cata.
+    // Don't add anything else to this file, because that will muddy the example.
+
+    [<Test>]
+    let ``Cata works`` () =
+        let property (x : FileSystemItem) =
+            FileSystemItemCata.runFileSystemItem idCata x = x
+
+        Check.QuickThrowOnFailure property
+
+// Note: this file is preserved as an example of writing an identity cata.
+// Don't add anything else to this file, because that will muddy the example.

WoofWare.Myriad.Plugins.Test/TestCataGenerator/TestGift.fs

@@ -0,0 +1,99 @@
+namespace WoofWare.Myriad.Plugins.Test
+
+open NUnit.Framework
+open ConsumePlugin
+open FsCheck
+open FsUnitTyped
+
+[<TestFixture>]
+module TestGift =
+
+    let idCata : GiftCata<_> =
+        {
+            Gift =
+                { new GiftCataCase<_> with
+                    member _.Book b = Gift.Book b
+                    member _.Boxed g = Gift.Boxed g
+                    member _.Chocolate g = Gift.Chocolate g
+                    member _.WithACard g message = Gift.WithACard (g, message)
+                    member _.Wrapped g paper = Gift.Wrapped (g, paper)
+                }
+        }
+
+    let totalCostCata : GiftCata<_> =
+        {
+            Gift =
+                { new GiftCataCase<_> with
+                    member _.Book b = b.price
+                    member _.Boxed g = g + 1.0m
+                    member _.Chocolate c = c.price
+                    member _.WithACard g message = g + 2.0m
+                    member _.Wrapped g paper = g + 0.5m
+                }
+        }
+
+    let descriptionCata : GiftCata<_> =
+        {
+            Gift =
+                { new GiftCataCase<_> with
+                    member _.Book b = b.title
+                    member _.Boxed g = $"%s{g} in a box"
+                    member _.Chocolate c = $"%O{c} chocolate"
+
+                    member _.WithACard g message =
+                        $"%s{g} with a card saying '%s{message}'"
+
+                    member _.Wrapped g paper = $"%s{g} wrapped in %A{paper} paper"
+                }
+        }
+
+    [<Test>]
+    let ``Cata works`` () =
+        let property (x : Gift) = GiftCata.runGift idCata x = x
+
+        Check.QuickThrowOnFailure property
+
+    [<Test>]
+    let ``Example from docs`` () =
+        let wolfHall =
+            {
+                title = "Wolf Hall"
+                price = 20m
+            }
+
+        let yummyChoc =
+            {
+                chocType = SeventyPercent
+                price = 5m
+            }
+
+        let birthdayPresent =
+            WithACard (Wrapped (Book wolfHall, HappyBirthday), "Happy Birthday")
+
+        let christmasPresent = Wrapped (Boxed (Chocolate yummyChoc), HappyHolidays)
+
+        GiftCata.runGift totalCostCata birthdayPresent |> shouldEqual 22.5m
+
+        GiftCata.runGift descriptionCata christmasPresent
+        |> shouldEqual "SeventyPercent chocolate in a box wrapped in HappyHolidays paper"
+
+        let deeplyNestedBox depth =
+            let rec loop depth boxSoFar =
+                match depth with
+                | 0 -> boxSoFar
+                | n -> loop (n - 1) (Boxed boxSoFar)
+
+            loop depth (Book wolfHall)
+
+        deeplyNestedBox 10 |> GiftCata.runGift totalCostCata |> shouldEqual 30.0M
+        deeplyNestedBox 100 |> GiftCata.runGift totalCostCata |> shouldEqual 120.0M
+        deeplyNestedBox 1000 |> GiftCata.runGift totalCostCata |> shouldEqual 1020.0M
+        deeplyNestedBox 10000 |> GiftCata.runGift totalCostCata |> shouldEqual 10020.0M
+
+        deeplyNestedBox 100000
+        |> GiftCata.runGift totalCostCata
+        |> shouldEqual 100020.0M
+
+        deeplyNestedBox 1000000
+        |> GiftCata.runGift totalCostCata
+        |> shouldEqual 1000020.0M

WoofWare.Myriad.Plugins.Test/TestCataGenerator/TestMyList.fs

@@ -0,0 +1,77 @@
+namespace WoofWare.Myriad.Plugins.Test
+
+open NUnit.Framework
+open FsCheck
+open FsUnitTyped
+open ConsumePlugin
+
+[<TestFixture>]
+module TestMyList =
+
+    let idCata<'a> : MyListCata<'a, _> =
+        {
+            MyList =
+                { new MyListCataCase<'a, _> with
+                    member _.Nil = MyList.Nil
+
+                    member _.Cons head tail =
+                        MyList.Cons
+                            {
+                                Head = head
+                                Tail = tail
+                            }
+                }
+        }
+
+    [<Test>]
+    let ``Cata works`` () =
+        let property (x : MyList<int>) = MyListCata.runMyList idCata x = x
+
+        Check.QuickThrowOnFailure property
+
+    let toListCata<'a> =
+        {
+            MyList =
+                { new MyListCataCase<'a, 'a list> with
+                    member _.Nil = []
+                    member _.Cons (head : 'a) (tail : 'a list) = head :: tail
+                }
+        }
+
+    let toListViaCata<'a> (l : MyList<'a>) : 'a list = MyListCata.runMyList toListCata l
+
+
+    [<Test>]
+    let ``Example of a fold converting to a new data structure`` () =
+        let rec toListNaive (l : MyList<int>) : int list =
+            match l with
+            | MyList.Nil -> []
+            | MyList.Cons consCell -> consCell.Head :: toListNaive consCell.Tail
+
+        Check.QuickThrowOnFailure (fun l -> toListNaive l = toListViaCata l)
+
+    [<Test>]
+    let ``Example of equivalence with FoldBack`` () =
+        let baseCase = 0L
+        let atLeaf (head : int) (tail : int64) : int64 = int64 head + tail
+
+        let sumCata =
+            {
+                MyList =
+                    { new MyListCataCase<int, int64> with
+                        member _.Nil = baseCase
+                        member _.Cons (head : int) (tail : int64) = atLeaf head tail
+                    }
+            }
+
+        let viaCata (l : MyList<int>) : int64 = MyListCata.runMyList sumCata l
+
+        let viaFold (l : MyList<int>) : int64 =
+            // choose your favourite "to list" method - here I use the cata
+            // but that could have been done naively
+            (toListViaCata l, baseCase)
+            ||> List.foldBack (fun elt state -> atLeaf elt state)
+
+        let property (l : MyList<int>) = viaCata l = viaFold l
+
+        Check.QuickThrowOnFailure property

WoofWare.Myriad.Plugins.Test/TestCataGenerator/TestMyList2.fs

@@ -0,0 +1,25 @@
+namespace WoofWare.Myriad.Plugins.Test
+
+open NUnit.Framework
+open FsCheck
+open FsUnitTyped
+open ConsumePlugin
+
+[<TestFixture>]
+module TestMyList2 =
+
+    let idCata<'a> : MyList2Cata<'a, _> =
+        {
+            MyList2 =
+                { new MyList2CataCase<'a, _> with
+                    member _.Nil = MyList2.Nil
+
+                    member _.Cons (head : 'a) (tail : MyList2<'a>) = MyList2.Cons (head, tail)
+                }
+        }
+
+    [<Test>]
+    let ``Cata works`` () =
+        let property (x : MyList2<int>) = MyList2Cata.runMyList2 idCata x = x
+
+        Check.QuickThrowOnFailure property

WoofWare.Myriad.Plugins.Test/TestHttpClient/TestPureGymRestApi.fs

@@ -209,10 +209,7 @@ module TestPureGymRestApi =
 
     [<TestCaseSource(nameof sessionsCases)>]
     let ``Test GetSessions``
-        (
-            baseUri : Uri,
-            (startDate : DateOnly, (endDate : DateOnly, (json : string, expected : Sessions)))
-        )
+        (baseUri : Uri, (startDate : DateOnly, (endDate : DateOnly, (json : string, expected : Sessions))))
         =
         let proc (message : HttpRequestMessage) : HttpResponseMessage Async =
             async {
@@ -237,6 +234,33 @@ module TestPureGymRestApi =
 
         api.GetSessions(startDate, endDate).Result |> shouldEqual expected
 
+    [<TestCaseSource(nameof sessionsCases)>]
+    let ``Test GetSessionsWithQuery``
+        (baseUri : Uri, (startDate : DateOnly, (endDate : DateOnly, (json : string, expected : Sessions))))
+        =
+        let proc (message : HttpRequestMessage) : HttpResponseMessage Async =
+            async {
+                message.Method |> shouldEqual HttpMethod.Get
+
+                // This one is specified as being absolute, in its attribute on the IPureGymApi type
+                let expectedUri =
+                    let fromDate = dateOnlyToString startDate
+                    let toDate = dateOnlyToString endDate
+                    $"https://example.com/v2/gymSessions/member?foo=1&fromDate=%s{fromDate}&toDate=%s{toDate}"
+
+                message.RequestUri.ToString () |> shouldEqual expectedUri
+
+                let content = new StringContent (json)
+                let resp = new HttpResponseMessage (HttpStatusCode.OK)
+                resp.Content <- content
+                return resp
+            }
+
+        use client = HttpClientMock.make baseUri proc
+        let api = PureGymApi.make client
+
+        api.GetSessionsWithQuery(startDate, endDate).Result |> shouldEqual expected
+
     [<Test>]
     let ``URI example`` () =
         let proc (message : HttpRequestMessage) : HttpResponseMessage Async =
@@ -260,3 +284,37 @@ module TestPureGymRestApi =
         uri.ToString () |> shouldEqual "https://patrick@en.wikipedia.org/wiki/foo"
         uri.UserInfo |> shouldEqual "patrick"
         uri.Host |> shouldEqual "en.wikipedia.org"
+
+    [<TestCase false>]
+    [<TestCase true>]
+    let ``Map<string, string> option example`` (isSome : bool) =
+        let proc (message : HttpRequestMessage) : HttpResponseMessage Async =
+            async {
+                message.Method |> shouldEqual HttpMethod.Post
+
+                message.RequestUri.ToString () |> shouldEqual "https://whatnot.com/some/url"
+                let! content = message.Content.ReadAsStringAsync () |> Async.AwaitTask
+
+                if isSome then
+                    content |> shouldEqual """{"hi":"bye"}"""
+                else
+                    content |> shouldEqual "null"
+
+                let content = new StringContent (content)
+
+                let resp = new HttpResponseMessage (HttpStatusCode.OK)
+                resp.Content <- content
+                return resp
+            }
+
+        use client = HttpClientMock.makeNoUri proc
+        let api = PureGymApi.make client
+
+        let expected =
+            if isSome then
+                [ "hi", "bye" ] |> Map.ofList |> Some
+            else
+                None
+
+        let actual = api.PostStringToString(expected).Result
+        actual |> shouldEqual expected

WoofWare.Myriad.Plugins.Test/TestHttpClient/TestVariableHeader.fs

@@ -0,0 +1,108 @@
+namespace WoofWare.Myriad.Plugins.Test
+
+open System
+open System.Net
+open System.Net.Http
+open System.Threading
+open NUnit.Framework
+open FsUnitTyped
+open PureGym
+
+[<TestFixture>]
+module TestVariableHeader =
+
+    [<Test>]
+    let ``Headers are set`` () : unit =
+        let proc (message : HttpRequestMessage) : HttpResponseMessage Async =
+            async {
+                message.Method |> shouldEqual HttpMethod.Get
+
+                message.RequestUri.ToString ()
+                |> shouldEqual "https://example.com/endpoint/param"
+
+                let headers =
+                    [
+                        for h in message.Headers do
+                            yield $"%s{h.Key}: %s{Seq.exactlyOne h.Value}"
+                    ]
+                    |> String.concat "\n"
+
+                let content = new StringContent (headers)
+                let resp = new HttpResponseMessage (HttpStatusCode.OK)
+                resp.Content <- content
+                return resp
+            }
+
+        use client = HttpClientMock.make (Uri "https://example.com") proc
+
+        let someHeaderCount = ref 10
+
+        let someHeader () =
+            (Interlocked.Increment someHeaderCount : int).ToString ()
+
+        let someOtherHeaderCount = ref -100
+
+        let someOtherHeader () =
+            Interlocked.Increment someOtherHeaderCount
+
+        let api = ApiWithHeaders.make someHeader someOtherHeader client
+
+        someHeaderCount.Value |> shouldEqual 10
+        someOtherHeaderCount.Value |> shouldEqual -100
+
+        api.GetPathParam("param").Result.Split "\n"
+        |> Array.sort
+        |> shouldEqual [| "Authorization: -99" ; "Header-Name: Header-Value" ; "X-Foo: 11" |]
+
+        someHeaderCount.Value |> shouldEqual 11
+        someOtherHeaderCount.Value |> shouldEqual -99
+
+    [<Test>]
+    let ``Headers get re-evaluated every time`` () : unit =
+        let proc (message : HttpRequestMessage) : HttpResponseMessage Async =
+            async {
+                message.Method |> shouldEqual HttpMethod.Get
+
+                message.RequestUri.ToString ()
+                |> shouldEqual "https://example.com/endpoint/param"
+
+                let headers =
+                    [
+                        for h in message.Headers do
+                            yield $"%s{h.Key}: %s{Seq.exactlyOne h.Value}"
+                    ]
+                    |> String.concat "\n"
+
+                let content = new StringContent (headers)
+                let resp = new HttpResponseMessage (HttpStatusCode.OK)
+                resp.Content <- content
+                return resp
+            }
+
+        use client = HttpClientMock.make (Uri "https://example.com") proc
+
+        let someHeaderCount = ref 10
+
+        let someHeader () =
+            (Interlocked.Increment someHeaderCount : int).ToString ()
+
+        let someOtherHeaderCount = ref -100
+
+        let someOtherHeader () =
+            Interlocked.Increment someOtherHeaderCount
+
+        let api = ApiWithHeaders.make someHeader someOtherHeader client
+
+        someHeaderCount.Value |> shouldEqual 10
+        someOtherHeaderCount.Value |> shouldEqual -100
+
+        api.GetPathParam("param").Result.Split "\n"
+        |> Array.sort
+        |> shouldEqual [| "Authorization: -99" ; "Header-Name: Header-Value" ; "X-Foo: 11" |]
+
+        api.GetPathParam("param").Result.Split "\n"
+        |> Array.sort
+        |> shouldEqual [| "Authorization: -98" ; "Header-Name: Header-Value" ; "X-Foo: 12" |]
+
+        someHeaderCount.Value |> shouldEqual 12
+        someOtherHeaderCount.Value |> shouldEqual -98

WoofWare.Myriad.Plugins.Test/TestJsonSerialize/TestJsonSerde.fs

@@ -2,6 +2,9 @@ namespace WoofWare.Myriad.Plugins.Test
 
 open System
 open System.Collections.Generic
+open System.IO
+open System.Text
+open System.Text.Json
 open System.Text.Json.Nodes
 open NUnit.Framework
 open FsCheck
@@ -19,7 +22,7 @@ module TestJsonSerde =
 
     let rec innerGen (count : int) : Gen<InnerTypeWithBoth> =
         gen {
-            let! s = Arb.generate<NonNull<string>>
+            let! guid = Arb.generate<Guid>
             let! mapKeys = Gen.listOf Arb.generate<NonNull<string>>
             let mapKeys = mapKeys |> List.map _.Get |> List.distinct
             let! mapValues = Gen.listOfLength mapKeys.Length uriGen
@@ -59,7 +62,7 @@ module TestJsonSerde =
 
             return
                 {
-                    Thing = s.Get
+                    Thing = guid
                     Map = map
                     ReadOnlyDict = readOnlyDict
                     Dict = dict
@@ -101,3 +104,23 @@ module TestJsonSerde =
             true
 
         property |> Prop.forAll (Arb.fromGen outerGen) |> Check.QuickThrowOnFailure
+
+    [<Test>]
+    let ``Guids are treated just like strings`` () =
+        let guidStr = "b1e7496e-6e79-4158-8579-a01de355d3b2"
+        let guid = Guid.Parse guidStr
+
+        let node =
+            {
+                Thing = guid
+                Map = Map.empty
+                ReadOnlyDict = readOnlyDict []
+                Dict = dict []
+                ConcreteDict = Dictionary ()
+            }
+            |> InnerTypeWithBoth.toJsonNode
+
+        node.ToJsonString ()
+        |> shouldEqual (
+            sprintf """{"it\u0027s-a-me":"%s","map":{},"readOnlyDict":{},"dict":{},"concreteDict":{}}""" guidStr
+        )

WoofWare.Myriad.Plugins.Test/TestSurface.fs

@@ -6,7 +6,7 @@ open ApiSurface
 
 [<TestFixture>]
 module TestSurface =
-    let assembly = typeof<RemoveOptionsAttribute>.Assembly
+    let assembly = typeof<RemoveOptionsGenerator>.Assembly
 
     [<Test>]
     let ``Ensure API surface has not been modified`` () = ApiSurface.assertIdentical assembly

WoofWare.Myriad.Plugins.Test/WoofWare.Myriad.Plugins.Test.fsproj

@@ -19,20 +19,26 @@
     <Compile Include="TestHttpClient\TestBasePath.fs" />
     <Compile Include="TestHttpClient\TestBodyParam.fs" />
     <Compile Include="TestHttpClient\TestVaultClient.fs" />
+    <Compile Include="TestHttpClient\TestVariableHeader.fs" />
     <Compile Include="TestMockGenerator\TestMockGenerator.fs" />
+    <Compile Include="TestJsonSerialize\TestJsonSerde.fs" />
+    <Compile Include="TestCataGenerator\TestCataGenerator.fs" />
+    <Compile Include="TestCataGenerator\TestDirectory.fs" />
+    <Compile Include="TestCataGenerator\TestGift.fs" />
+    <Compile Include="TestCataGenerator\TestMyList.fs" />
+    <Compile Include="TestCataGenerator\TestMyList2.fs" />
     <Compile Include="TestRemoveOptions.fs"/>
     <Compile Include="TestSurface.fs"/>
+    <None Include="../.github/workflows/dotnet.yaml" />
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="ApiSurface" Version="4.0.25"/>
+    <PackageReference Include="ApiSurface" Version="4.0.39"/>
     <PackageReference Include="FsCheck" Version="2.16.6"/>
     <PackageReference Include="FsUnit" Version="6.0.0"/>
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.8.0"/>
-    <PackageReference Include="NUnit" Version="4.0.1"/>
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.9.0"/>
+    <PackageReference Include="NUnit" Version="4.1.0"/>
     <PackageReference Include="NUnit3TestAdapter" Version="4.5.0"/>
-    <PackageReference Include="NUnit.Analyzers" Version="3.10.0"/>
-    <PackageReference Include="coverlet.collector" Version="6.0.0"/>
   </ItemGroup>
 
   <ItemGroup>
@@ -40,8 +46,4 @@
     <ProjectReference Include="..\ConsumePlugin\ConsumePlugin.fsproj"/>
   </ItemGroup>
 
-  <ItemGroup>
-    <Compile Include="TestJsonSerialize\TestJsonSerde.fs" />
-  </ItemGroup>
-
 </Project>

WoofWare.Myriad.Plugins/AstHelper.fs

@@ -33,11 +33,30 @@ type internal MemberInfo =
         IsMutable : bool
     }
 
+[<RequireQualifiedAccess>]
+type internal PropertyAccessors =
+    | Get
+    | Set
+    | GetSet
+
+type internal PropertyInfo =
+    {
+        Type : SynType
+        Accessibility : SynAccess option
+        Attributes : SynAttribute list
+        XmlDoc : PreXmlDoc option
+        Accessors : PropertyAccessors
+        IsInline : bool
+        Identifier : Ident
+    }
+
 type internal InterfaceType =
     {
         Attributes : SynAttribute list
         Name : LongIdent
+        Inherits : SynType list
         Members : MemberInfo list
+        Properties : PropertyInfo list
         Generics : SynTyparDecls option
         Accessibility : SynAccess option
     }
@@ -52,6 +71,30 @@ type internal RecordType =
         Accessibility : SynAccess option
     }
 
+/// Anything that is part of an ADT.
+/// A record is a product of stuff; this type represents one of those stuffs.
+type internal AdtNode =
+    {
+        Type : SynType
+        Name : Ident option
+        /// An ordered list, so you can look up any given generic within `this.Type`
+        /// to discover what its index is in the parent DU which defined it.
+        GenericsOfParent : SynTyparDecl list
+    }
+
+/// A DU is a sum of products (e.g. `type Thing = Foo of a * b`);
+/// similarly a record is a product.
+/// This type represents a product in that sense.
+type internal AdtProduct =
+    {
+        Name : SynIdent
+        Fields : AdtNode list
+        /// This AdtProduct represents a product in which there might be
+        /// some bound type parameters. This field lists the bound
+        /// type parameters in the order they appeared on the parent type.
+        Generics : SynTyparDecl list
+    }
+
 [<RequireQualifiedAccess>]
 module internal AstHelper =
 
@@ -89,6 +132,11 @@ module internal AstHelper =
         // TODO: consider Microsoft.FSharp.Option or whatever it is
         | _ -> false
 
+    let isUnitIdent (ident : SynLongIdent) : bool =
+        match ident.LongIdent with
+        | [ i ] when System.String.Equals (i.idText, "unit", System.StringComparison.OrdinalIgnoreCase) -> true
+        | _ -> false
+
     let isListIdent (ident : SynLongIdent) : bool =
         match ident.LongIdent with
         | [ i ] when System.String.Equals (i.idText, "list", System.StringComparison.OrdinalIgnoreCase) -> true
@@ -230,6 +278,119 @@ module internal AstHelper =
             ((toFun (List.map fst inputArgs) inputRet), hasParen) :: args, ret
         | _ -> [], ty
 
+    let private parseMember (slotSig : SynValSig) (flags : SynMemberFlags) : Choice<MemberInfo, PropertyInfo> =
+        if not flags.IsInstance then
+            failwith "member was not an instance member"
+
+        let propertyAccessors =
+            match flags.MemberKind with
+            | SynMemberKind.Member -> None
+            | SynMemberKind.PropertyGet -> Some PropertyAccessors.Get
+            | SynMemberKind.PropertySet -> Some PropertyAccessors.Set
+            | SynMemberKind.PropertyGetSet -> Some PropertyAccessors.GetSet
+            | kind -> failwithf "Unrecognised member kind: %+A" kind
+
+        match slotSig with
+        | SynValSig (attrs,
+                     SynIdent.SynIdent (ident, _),
+                     _typeParams,
+                     synType,
+                     _arity,
+                     isInline,
+                     isMutable,
+                     xmlDoc,
+                     accessibility,
+                     synExpr,
+                     _,
+                     _) ->
+
+            match synExpr with
+            | Some _ -> failwith "literal members are not supported"
+            | None -> ()
+
+            let attrs = attrs |> List.collect _.Attributes
+
+            let args, ret = getType synType
+
+            let args =
+                args
+                |> List.map (fun (args, hasParen) ->
+                    match args with
+                    | SynType.Tuple (false, path, _) -> extractTupledTypes path
+                    | SynType.SignatureParameter _ ->
+                        let arg, hasParen = convertSigParam args
+
+                        {
+                            HasParen = hasParen
+                            Args = [ arg ]
+                        }
+                    | SynType.LongIdent (SynLongIdent (ident, _, _)) ->
+                        {
+                            HasParen = false
+                            Args =
+                                {
+                                    Attributes = []
+                                    IsOptional = false
+                                    Id = None
+                                    Type = SynType.CreateLongIdent (SynLongIdent.CreateFromLongIdent ident)
+                                }
+                                |> List.singleton
+                        }
+                    | SynType.Var (typar, _) ->
+                        {
+                            HasParen = false
+                            Args =
+                                {
+                                    Attributes = []
+                                    IsOptional = false
+                                    Id = None
+                                    Type = SynType.Var (typar, range0)
+                                }
+                                |> List.singleton
+                        }
+                    | arg ->
+                        {
+                            HasParen = false
+                            Args =
+                                {
+                                    Attributes = []
+                                    IsOptional = false
+                                    Id = None
+                                    Type = arg
+                                }
+                                |> List.singleton
+                        }
+                    |> fun ty ->
+                        { ty with
+                            HasParen = ty.HasParen || hasParen
+                        }
+                )
+
+            match propertyAccessors with
+            | None ->
+                {
+                    ReturnType = ret
+                    Args = args
+                    Identifier = ident
+                    Attributes = attrs
+                    XmlDoc = Some xmlDoc
+                    Accessibility = accessibility
+                    IsInline = isInline
+                    IsMutable = isMutable
+                }
+                |> Choice1Of2
+            | Some accessors ->
+                {
+                    Type = ret
+                    Accessibility = accessibility
+                    Attributes = attrs
+                    XmlDoc = Some xmlDoc
+                    Accessors = accessors
+                    IsInline = isInline
+                    Identifier = ident
+                }
+                |> Choice2Of2
+
     /// Assumes that the input type is an ObjectModel, i.e. a `type Foo = member ...`
     let parseInterface (interfaceType : SynTypeDefn) : InterfaceType =
         let (SynTypeDefn (SynComponentInfo (attrs, typars, _, interfaceName, _, _, accessibility, _),
@@ -242,110 +403,101 @@ module internal AstHelper =
 
         let attrs = attrs |> List.collect (fun s -> s.Attributes)
 
-        let members =
+        let members, inherits =
             match synTypeDefnRepr with
             | SynTypeDefnRepr.ObjectModel (_kind, members, _) ->
                 members
                 |> List.map (fun defn ->
                     match defn with
-                    | SynMemberDefn.AbstractSlot (slotSig, flags, _, _) ->
-                        match flags.MemberKind with
-                        | SynMemberKind.Member -> ()
-                        | kind -> failwithf "Unrecognised member kind: %+A" kind
-
-                        if not flags.IsInstance then
-                            failwith "member was not an instance member"
-
-                        match slotSig with
-                        | SynValSig (attrs,
-                                     SynIdent.SynIdent (ident, _),
-                                     _typeParams,
-                                     synType,
-                                     arity,
-                                     isInline,
-                                     isMutable,
-                                     xmlDoc,
-                                     accessibility,
-                                     synExpr,
-                                     _,
-                                     _) ->
-
-                            match synExpr with
-                            | Some _ -> failwith "literal members are not supported"
-                            | None -> ()
-
-                            let attrs = attrs |> List.collect (fun attr -> attr.Attributes)
-
-                            let args, ret = getType synType
-
-                            let args =
-                                args
-                                |> List.map (fun (args, hasParen) ->
-                                    match args with
-                                    | SynType.Tuple (false, path, _) -> extractTupledTypes path
-                                    | SynType.SignatureParameter _ ->
-                                        let arg, hasParen = convertSigParam args
-
-                                        {
-                                            HasParen = hasParen
-                                            Args = [ arg ]
-                                        }
-                                    | SynType.LongIdent (SynLongIdent (ident, _, _)) ->
-                                        {
-                                            HasParen = false
-                                            Args =
-                                                {
-                                                    Attributes = []
-                                                    IsOptional = false
-                                                    Id = None
-                                                    Type =
-                                                        SynType.CreateLongIdent (
-                                                            SynLongIdent.CreateFromLongIdent ident
-                                                        )
-                                                }
-                                                |> List.singleton
-                                        }
-                                    | SynType.Var (typar, _) ->
-                                        {
-                                            HasParen = false
-                                            Args =
-                                                {
-                                                    Attributes = []
-                                                    IsOptional = false
-                                                    Id = None
-                                                    Type = SynType.Var (typar, range0)
-                                                }
-                                                |> List.singleton
-                                        }
-                                    | _ -> failwith $"Unrecognised args in interface method declaration: %+A{args}"
-                                    |> fun ty ->
-                                        { ty with
-                                            HasParen = ty.HasParen || hasParen
-                                        }
-                                )
-
-                            {
-                                ReturnType = ret
-                                Args = args
-                                Identifier = ident
-                                Attributes = attrs
-                                XmlDoc = Some xmlDoc
-                                Accessibility = accessibility
-                                IsInline = isInline
-                                IsMutable = isMutable
-                            }
+                    | SynMemberDefn.AbstractSlot (slotSig, flags, _, _) -> Choice1Of2 (parseMember slotSig flags)
+                    | SynMemberDefn.Inherit (baseType, _asIdent, _) -> Choice2Of2 baseType
                     | _ -> failwith $"Unrecognised member definition: %+A{defn}"
                 )
             | _ -> failwith $"Unrecognised SynTypeDefnRepr for an interface type: %+A{synTypeDefnRepr}"
+            |> List.partitionChoice
+
+        let members, properties = members |> List.partitionChoice
 
         {
             Members = members
+            Properties = properties
             Name = interfaceName
+            Inherits = inherits
             Attributes = attrs
             Generics = typars
             Accessibility = accessibility
         }
 
+    let getUnionCases
+        (SynTypeDefn.SynTypeDefn (info, repr, _, _, _, _))
+        : AdtProduct list * SynTyparDecl list * SynAccess option
+        =
+        let typars, access =
+            match info with
+            | SynComponentInfo (_, typars, _, _, _, _, access, _) -> typars, access
+
+        let typars =
+            match typars with
+            | None -> []
+            | Some (SynTyparDecls.PrefixList (decls, _)) -> decls
+            | Some (SynTyparDecls.SinglePrefix (l, _)) -> [ l ]
+            | Some (SynTyparDecls.PostfixList (decls, constraints, _)) ->
+                if not constraints.IsEmpty then
+                    failwith "Constrained type parameters not currently supported"
+
+                decls
+
+        match repr with
+        | SynTypeDefnRepr.Simple (SynTypeDefnSimpleRepr.Union (_, cases, _), _) ->
+            let cases =
+                cases
+                |> List.map (fun (SynUnionCase.SynUnionCase (_, ident, kind, _, _, _, _)) ->
+                    match kind with
+                    | SynUnionCaseKind.FullType _ -> failwith "FullType union cases not supported"
+                    | SynUnionCaseKind.Fields fields ->
+                        {
+                            Name = ident
+                            Fields =
+                                fields
+                                |> List.map (fun (SynField.SynField (_, _, id, ty, _, _, _, _, _)) ->
+                                    {
+                                        Type = ty
+                                        Name = id
+                                        GenericsOfParent = typars
+                                    }
+                                )
+                            Generics = typars
+                        }
+                )
+
+            cases, typars, access
+        | _ -> failwithf "Failed to get union cases for type that was: %+A" repr
+
+    let getRecordFields (SynTypeDefn.SynTypeDefn (typeInfo, repr, _, _, _, _)) : AdtNode list =
+        let (SynComponentInfo.SynComponentInfo (typeParams = typars)) = typeInfo
+
+        let typars =
+            match typars with
+            | None -> []
+            | Some (SynTyparDecls.PrefixList (decls, _)) -> decls
+            | Some (SynTyparDecls.SinglePrefix (l, _)) -> [ l ]
+            | Some (SynTyparDecls.PostfixList (decls, constraints, _)) ->
+                if not constraints.IsEmpty then
+                    failwith "Constrained type parameters not currently supported"
+
+                decls
+
+        match repr with
+        | SynTypeDefnRepr.Simple (SynTypeDefnSimpleRepr.Record (_, fields, _), _) ->
+            fields
+            |> List.map (fun (SynField.SynField (_, _, ident, ty, _, _, _, _, _)) ->
+                {
+                    Name = ident
+                    Type = ty
+                    GenericsOfParent = typars
+                }
+            )
+        | _ -> failwithf "Failed to get record elements for type that was: %+A" repr
 
 [<AutoOpen>]
 module internal SynTypePatterns =
@@ -355,6 +507,11 @@ module internal SynTypePatterns =
             Some innerType
         | _ -> None
 
+    let (|UnitType|_|) (fieldType : SynType) : unit option =
+        match fieldType with
+        | SynType.LongIdent ident when AstHelper.isUnitIdent ident -> Some ()
+        | _ -> None
+
     let (|ListType|_|) (fieldType : SynType) =
         match fieldType with
         | SynType.App (SynType.LongIdent ident, _, [ innerType ], _, _, _, _) when AstHelper.isListIdent ident ->
@@ -430,6 +587,15 @@ module internal SynTypePatterns =
             | _ -> None
         | _ -> None
 
+    let (|Guid|_|) (fieldType : SynType) : unit option =
+        match fieldType with
+        | SynType.LongIdent ident ->
+            match ident.LongIdent |> List.map (fun i -> i.idText) with
+            | [ "System" ; "Guid" ]
+            | [ "Guid" ] -> Some ()
+            | _ -> None
+        | _ -> None
+
     let (|HttpResponseMessage|_|) (fieldType : SynType) : unit option =
         match fieldType with
         | SynType.LongIdent ident ->

WoofWare.Myriad.Plugins/HttpClientGenerator.fs

@@ -1,27 +1,25 @@
 namespace WoofWare.Myriad.Plugins
 
-open System
 open System.Net.Http
 open Fantomas.FCS.Syntax
+open Fantomas.FCS.SyntaxTrivia
 open Fantomas.FCS.Xml
 open Myriad.Core
 
-/// Attribute indicating a record type to which the "create HTTP client" Myriad
-/// generator should apply during build.
-/// This generator is intended to replicate much of the functionality of RestEase,
-/// i.e. to stamp out HTTP REST clients from interfaces defining the API.
-type HttpClientAttribute () =
-    inherit Attribute ()
-
 [<RequireQualifiedAccess>]
 module internal HttpClientGenerator =
     open Fantomas.FCS.Text.Range
     open Myriad.Core.Ast
 
+    [<RequireQualifiedAccess>]
+    type PathSpec =
+        | Verbatim of string
+        | MatchArgName
+
     type HttpAttribute =
         // TODO: Format parameter to these attrs
         | Query of string option
-        | Path of string
+        | Path of PathSpec
         | Body
 
     type Parameter =
@@ -52,8 +50,8 @@ module internal HttpClientGenerator =
         {
             /// E.g. HttpMethod.Get
             HttpMethod : HttpMethod
-            /// E.g. "v1/gyms/{gym_id}/attendance"
-            UrlTemplate : string
+            /// E.g. SynExpr.Const "v1/gyms/{gym_id}/attendance"
+            UrlTemplate : SynExpr
             TaskReturnType : SynType
             Args : Parameter list
             Identifier : Ident
@@ -74,57 +72,84 @@ module internal HttpClientGenerator =
         elif m = HttpMethod.Trace then "Trace"
         else failwith $"Unrecognised method: %+A{m}"
 
-    /// E.g. converts `[<Get "blah">]` to (HttpMethod.Get, "blah")
-    let extractHttpInformation (attrs : SynAttribute list) : HttpMethod * string =
+    /// E.g. converts `[<Get "blah">]` to (HttpMethod.Get, SynExpr.Const "blah")
+    let extractHttpInformation (attrs : SynAttribute list) : HttpMethod * SynExpr =
         let matchingAttrs =
             attrs
             |> List.choose (fun attr ->
                 match attr.TypeName.AsString with
                 | "Get"
                 | "GetAttribute"
+                | "WoofWare.Myriad.Plugins.RestEase.Get"
+                | "WoofWare.Myriad.Plugins.RestEase.GetAttribute"
                 | "RestEase.Get"
                 | "RestEase.GetAttribute" -> Some (HttpMethod.Get, attr.ArgExpr)
                 | "Post"
                 | "PostAttribute"
+                | "WoofWare.Myriad.Plugins.RestEase.Post"
+                | "WoofWare.Myriad.Plugins.RestEase.PostAttribute"
                 | "RestEase.Post"
                 | "RestEase.PostAttribute" -> Some (HttpMethod.Post, attr.ArgExpr)
                 | "Put"
                 | "PutAttribute"
+                | "WoofWare.Myriad.Plugins.RestEase.Put"
+                | "WoofWare.Myriad.Plugins.RestEase.PutAttribute"
                 | "RestEase.Put"
                 | "RestEase.PutAttribute" -> Some (HttpMethod.Put, attr.ArgExpr)
                 | "Delete"
                 | "DeleteAttribute"
+                | "WoofWare.Myriad.Plugins.RestEase.Delete"
+                | "WoofWare.Myriad.Plugins.RestEase.DeleteAttribute"
                 | "RestEase.Delete"
                 | "RestEase.DeleteAttribute" -> Some (HttpMethod.Delete, attr.ArgExpr)
                 | "Head"
                 | "HeadAttribute"
+                | "WoofWare.Myriad.Plugins.RestEase.Head"
+                | "WoofWare.Myriad.Plugins.RestEase.HeadAttribute"
                 | "RestEase.Head"
                 | "RestEase.HeadAttribute" -> Some (HttpMethod.Head, attr.ArgExpr)
                 | "Options"
                 | "OptionsAttribute"
+                | "WoofWare.Myriad.Plugins.RestEase.Options"
+                | "WoofWare.Myriad.Plugins.RestEase.OptionsAttribute"
                 | "RestEase.Options"
                 | "RestEase.OptionsAttribute" -> Some (HttpMethod.Options, attr.ArgExpr)
                 | "Patch"
                 | "PatchAttribute"
+                | "WoofWare.Myriad.Plugins.RestEase.Patch"
+                | "WoofWare.Myriad.Plugins.RestEase.PatchAttribute"
                 | "RestEase.Patch"
                 | "RestEase.PatchAttribute" -> Some (HttpMethod.Patch, attr.ArgExpr)
                 | "Trace"
                 | "TraceAttribute"
+                | "WoofWare.Myriad.Plugins.RestEase.Trace"
+                | "WoofWare.Myriad.Plugins.RestEase.TraceAttribute"
                 | "RestEase.Trace"
                 | "RestEase.TraceAttribute" -> Some (HttpMethod.Trace, attr.ArgExpr)
                 | _ -> None
             )
 
         match matchingAttrs with
-        | [ (meth, arg) ] ->
-            match arg with
-            | SynExpr.Const (SynConst.String (text, SynStringKind.Regular, _), _) -> meth, text
-            | arg ->
-                failwith $"Unrecognised AST member in attribute argument. Only regular strings are supported: %+A{arg}"
+        | [ (meth, arg) ] -> meth, arg
         | [] -> failwith "Required exactly one recognised RestEase attribute on member, but got none"
         | matchingAttrs ->
             failwith $"Required exactly one recognised RestEase attribute on member, but got %i{matchingAttrs.Length}"
 
+    /// Get the args associated with the Header attributes within the list.
+    let extractHeaderInformation (attrs : SynAttribute list) : SynExpr list list =
+        attrs
+        |> List.choose (fun attr ->
+            match attr.TypeName.AsString with
+            | "Header"
+            | "RestEase.Header"
+            | "WoofWare.Myriad.Plugins.RestEase.Header" ->
+                match attr.ArgExpr with
+                | SynExpr.Paren (SynExpr.Tuple (_, [ v1 ; v2 ], _, _), _, _, _) ->
+                    Some [ SynExpr.stripOptionalParen v1 ; SynExpr.stripOptionalParen v2 ]
+                | e -> Some [ SynExpr.stripOptionalParen e ]
+            | _ -> None
+        )
+
     let shouldAllowAnyStatusCode (attrs : SynAttribute list) : bool =
         attrs
         |> List.exists (fun attr ->
@@ -136,7 +161,14 @@ module internal HttpClientGenerator =
             | _ -> false
         )
 
-    let constructMember (info : MemberInfo) : SynMemberDefn =
+    /// constantHeaders are a list of (headerName, headerValue)
+    /// variableHeaders are a list of (headerName, selfPropertyToGetValueOf)
+    let constructMember
+        (constantHeaders : (SynExpr * SynExpr) list)
+        (variableHeaders : (SynExpr * Ident) list)
+        (info : MemberInfo)
+        : SynMemberDefn
+        =
         let valInfo =
             SynValInfo.SynValInfo (
                 [
@@ -166,27 +198,34 @@ module internal HttpClientGenerator =
                 None
             )
 
+        let args =
+            info.Args
+            |> List.map (fun arg ->
+                let argName =
+                    match arg.Id with
+                    | None -> failwith "TODO: create an arg name"
+                    | Some id -> id
+
+                let argType =
+                    if arg.IsOptional then
+                        SynType.CreateApp (
+                            SynType.CreateLongIdent (SynLongIdent.CreateString "option"),
+                            [ arg.Type ],
+                            isPostfix = true
+                        )
+                    else
+                        arg.Type
+
+                argName, SynPat.CreateTyped (SynPat.CreateNamed argName, argType)
+            )
+
+        let cancellationTokenArg =
+            match List.tryLast args with
+            | None -> failwith $"expected an optional cancellation token as final arg in %s{info.Identifier.idText}"
+            | Some (arg, _) -> arg
+
         let argPats =
-            let args =
-                info.Args
-                |> List.map (fun arg ->
-                    let argName =
-                        match arg.Id with
-                        | None -> failwith "TODO: create an arg name"
-                        | Some id -> id
-
-                    let argType =
-                        if arg.IsOptional then
-                            SynType.CreateApp (
-                                SynType.CreateLongIdent (SynLongIdent.CreateString "option"),
-                                [ arg.Type ],
-                                isPostfix = true
-                            )
-                        else
-                            arg.Type
-
-                    SynPat.CreateTyped (SynPat.CreateNamed argName, argType)
-                )
+            let args = args |> List.map snd
 
             SynPat.Tuple (false, args, List.replicate (args.Length - 1) range0, range0)
             |> SynPat.CreateParen
@@ -194,8 +233,10 @@ module internal HttpClientGenerator =
             |> SynArgPats.Pats
 
         let headPat =
+            let thisIdent = if variableHeaders.IsEmpty then "_" else "this"
+
             SynPat.LongIdent (
-                SynLongIdent.CreateFromLongIdent [ Ident.Create "_" ; info.Identifier ],
+                SynLongIdent.CreateFromLongIdent [ Ident.Create thisIdent ; info.Identifier ],
                 None,
                 None,
                 argPats,
@@ -204,23 +245,28 @@ module internal HttpClientGenerator =
             )
 
         let requestUriTrailer =
-            (SynExpr.CreateConstString info.UrlTemplate, info.Args)
+            (info.UrlTemplate, info.Args)
             ||> List.fold (fun template arg ->
                 (template, arg.Attributes)
                 ||> List.fold (fun template attr ->
                     match attr with
-                    | HttpAttribute.Path s ->
+                    | HttpAttribute.Path spec ->
                         let varName =
                             match arg.Id with
                             | None -> failwith "TODO: anonymous args"
                             | Some id -> id
 
+                        let substituteId =
+                            match spec with
+                            | PathSpec.Verbatim s -> s
+                            | PathSpec.MatchArgName -> varName.idText
+
                         template
                         |> SynExpr.callMethodArg
                             "Replace"
                             (SynExpr.CreateParenedTuple
                                 [
-                                    SynExpr.CreateConstString ("{" + s + "}")
+                                    SynExpr.CreateConstString ("{" + substituteId + "}")
                                     SynExpr.callMethod "ToString" (SynExpr.CreateIdent varName)
                                     |> SynExpr.pipeThroughFunction (
                                         SynExpr.CreateLongIdent (
@@ -262,6 +308,27 @@ module internal HttpClientGenerator =
                     | None -> failwith "Unable to get parameter variable name from anonymous parameter"
                     | Some id -> id
 
+                let urlSeparator =
+                    // apparent Myriad bug: `IndexOf '?'` gets formatted as `IndexOf ?` which is clearly wrong
+                    let questionMark =
+                        SynExpr.CreateParen (
+                            SynExpr.CreateApp (
+                                SynExpr.CreateIdentString "char",
+                                SynExpr.CreateConst (SynConst.Int32 63)
+                            )
+                        )
+
+                    let containsQuestion =
+                        info.UrlTemplate
+                        |> SynExpr.callMethodArg "IndexOf" questionMark
+                        |> SynExpr.greaterThanOrEqual (SynExpr.CreateConst (SynConst.Int32 0))
+
+                    SynExpr.ifThenElse
+                        containsQuestion
+                        (SynExpr.CreateConst (SynConst.CreateString "?"))
+                        (SynExpr.CreateConst (SynConst.CreateString "&"))
+                    |> SynExpr.CreateParen
+
                 let prefix =
                     SynExpr.CreateIdent firstValueId
                     |> SynExpr.toString firstValue.Type
@@ -270,7 +337,7 @@ module internal HttpClientGenerator =
                         SynExpr.CreateLongIdent (SynLongIdent.Create [ "System" ; "Web" ; "HttpUtility" ; "UrlEncode" ])
                     )
                     |> SynExpr.CreateParen
-                    |> SynExpr.plus (SynExpr.CreateConstString ("?" + firstKey + "="))
+                    |> SynExpr.plus (SynExpr.plus urlSeparator (SynExpr.CreateConstString (firstKey + "=")))
 
                 (prefix, queryParams)
                 ||> List.fold (fun uri (paramKey, paramValue) ->
@@ -495,12 +562,18 @@ module internal HttpClientGenerator =
                                     |> SynExpr.pipeThroughFunction (
                                         SynExpr.createLambda
                                             "node"
-                                            (SynExpr.CreateApp (
-                                                SynExpr.CreateLongIdent (
-                                                    SynLongIdent.Create [ "node" ; "ToJsonString" ]
-                                                ),
-                                                SynExpr.CreateConst SynConst.Unit
-                                            ))
+                                            (SynExpr.ifThenElse
+                                                (SynExpr.CreateApp (
+                                                    SynExpr.CreateIdentString "isNull",
+                                                    SynExpr.CreateIdentString "node"
+                                                ))
+                                                (SynExpr.CreateApp (
+                                                    SynExpr.CreateLongIdent (
+                                                        SynLongIdent.Create [ "node" ; "ToJsonString" ]
+                                                    ),
+                                                    SynExpr.CreateConst SynConst.Unit
+                                                ))
+                                                (SynExpr.CreateConst (SynConst.CreateString "null")))
                                     )
                                 ),
                                 range0
@@ -561,6 +634,38 @@ module internal HttpClientGenerator =
                     )
                 )
 
+            let setVariableHeaders =
+                variableHeaders
+                |> List.map (fun (headerName, callToGetValue) ->
+                    Do (
+                        SynExpr.CreateApp (
+                            SynExpr.CreateLongIdent (SynLongIdent.Create [ "httpMessage" ; "Headers" ; "Add" ]),
+                            SynExpr.CreateParenedTuple
+                                [
+                                    headerName
+                                    SynExpr.CreateApp (
+                                        SynExpr.CreateLongIdent (
+                                            SynLongIdent.CreateFromLongIdent
+                                                [ Ident.Create "this" ; callToGetValue ; Ident.Create "ToString" ]
+                                        ),
+                                        SynExpr.CreateConst SynConst.Unit
+                                    )
+                                ]
+                        )
+                    )
+                )
+
+            let setConstantHeaders =
+                constantHeaders
+                |> List.map (fun (headerName, headerValue) ->
+                    Do (
+                        SynExpr.CreateApp (
+                            SynExpr.CreateLongIdent (SynLongIdent.Create [ "httpMessage" ; "Headers" ; "Add" ]),
+                            SynExpr.CreateParenedTuple [ headerName ; headerValue ]
+                        )
+                    )
+                )
+
             [
                 yield LetBang ("ct", SynExpr.CreateLongIdent (SynLongIdent.Create [ "Async" ; "CancellationToken" ]))
                 yield Let ("uri", requestUri)
@@ -579,6 +684,9 @@ module internal HttpClientGenerator =
 
                 yield! handleBodyParams
 
+                yield! setVariableHeaders
+                yield! setConstantHeaders
+
                 yield
                     LetBang (
                         "response",
@@ -612,7 +720,7 @@ module internal HttpClientGenerator =
                     yield jsonNode
             ]
             |> SynExpr.createCompExpr "async" returnExpr
-            |> SynExpr.startAsTask
+            |> SynExpr.startAsTask (SynLongIdent.CreateFromLongIdent [ cancellationTokenArg ])
 
         SynMemberDefn.Member (
             SynBinding.SynBinding (
@@ -637,6 +745,10 @@ module internal HttpClientGenerator =
         attrs
         |> List.choose (fun attr ->
             match attr.TypeName.AsString with
+            | "RestEase.Query"
+            | "RestEase.QueryAttribute"
+            | "WoofWare.Myriad.Plugins.RestEase.Query"
+            | "WoofWare.Myriad.Plugins.RestEase.QueryAttribute"
             | "Query"
             | "QueryAttribute" ->
                 match attr.ArgExpr with
@@ -645,12 +757,22 @@ module internal HttpClientGenerator =
                     Some (HttpAttribute.Query (Some s))
                 | SynExpr.Const (a, _) -> failwith $"unrecognised constant arg to the Query attribute: %+A{a}"
                 | _ -> None
+            | "RestEase.Path"
+            | "RestEase.PathAttribute"
+            | "WoofWare.Myriad.Plugins.RestEase.Path"
+            | "WoofWare.Myriad.Plugins.RestEase.PathAttribute"
             | "Path"
             | "PathAttribute" ->
                 match attr.ArgExpr with
-                | SynExpr.Const (SynConst.String (s, SynStringKind.Regular, _), _) -> Some (HttpAttribute.Path s)
+                | SynExpr.Const (SynConst.String (s, SynStringKind.Regular, _), _) ->
+                    Some (HttpAttribute.Path (PathSpec.Verbatim s))
+                | SynExpr.Const (SynConst.Unit, _) -> Some (HttpAttribute.Path PathSpec.MatchArgName)
                 | SynExpr.Const (a, _) -> failwith $"unrecognised constant arg to the Path attribute: %+A{a}"
                 | _ -> None
+            | "RestEase.Body"
+            | "RestEase.BodyAttribute"
+            | "WoofWare.Myriad.Plugins.RestEase.Body"
+            | "WoofWare.Myriad.Plugins.RestEase.BodyAttribute"
             | "Body"
             | "BodyAttribute" ->
                 match attr.ArgExpr with
@@ -666,8 +788,10 @@ module internal HttpClientGenerator =
             match attr.TypeName.AsString with
             | "BasePath"
             | "RestEase.BasePath"
+            | "WoofWare.Myriad.Plugins.RestEase.BasePath"
             | "BasePathAttribute"
-            | "RestEase.BasePathAttribute" -> Some attr.ArgExpr
+            | "RestEase.BasePathAttribute"
+            | "WoofWare.Myriad.Plugins.RestEase.BasePathAttribute" -> Some attr.ArgExpr
             | _ -> None
         )
 
@@ -677,8 +801,10 @@ module internal HttpClientGenerator =
             match attr.TypeName.AsString with
             | "BaseAddress"
             | "RestEase.BaseAddress"
+            | "WoofWare.Myriad.Plugins.RestEase.BaseAddress"
             | "BaseAddressAttribute"
-            | "RestEase.BaseAddressAttribute" -> Some attr.ArgExpr
+            | "RestEase.BaseAddressAttribute"
+            | "WoofWare.Myriad.Plugins.RestEase.BaseAddressAttribute" -> Some attr.ArgExpr
             | _ -> None
         )
 
@@ -690,10 +816,52 @@ module internal HttpClientGenerator =
         =
         let interfaceType = AstHelper.parseInterface interfaceType
 
+        if not (List.isEmpty interfaceType.Inherits) then
+            failwith
+                "HttpClientGenerator does not support inheritance. Remove the `inherit` keyword if you want to use this generator."
+
+        let constantHeaders =
+            interfaceType.Attributes
+            |> extractHeaderInformation
+            |> List.map (fun exprs ->
+                match exprs with
+                | [ key ; value ] -> key, value
+                | [] ->
+                    failwith
+                        "Expected constant header parameters to be of the form [<Header (key, value)>], but got no args"
+                | [ _ ] ->
+                    failwith
+                        "Expected constant header parameters to be of the form [<Header (key, value)>], but got only one arg"
+                | _ ->
+                    failwith
+                        "Expected constant header parameters to be of the form [<Header (key, value)>], but got more than two args"
+            )
+
         let baseAddress = extractBaseAddress interfaceType.Attributes
         let basePath = extractBasePath interfaceType.Attributes
 
-        let members =
+        let properties =
+            interfaceType.Properties
+            |> List.map (fun pi ->
+                let headerInfo =
+                    match extractHeaderInformation pi.Attributes with
+                    | [ [ x ] ] -> x
+                    | [ xs ] ->
+                        failwith
+                            "Expected exactly one Header parameter on the member, with exactly one arg; got one Header parameter with non-1-many args"
+                    | [] ->
+                        failwith
+                            "Expected exactly one Header parameter on the member, with exactly one arg; got no Header parameters"
+                    | _ ->
+                        failwith
+                            "Expected exactly one Header parameter on the member, with exactly one arg; got multiple Header parameters"
+
+                headerInfo, pi
+            )
+
+        let nonPropertyMembers =
+            let properties = properties |> List.map (fun (header, pi) -> header, pi.Identifier)
+
             interfaceType.Members
             |> List.map (fun mem ->
                 let httpMethod, url = extractHttpInformation mem.Attributes
@@ -740,8 +908,57 @@ module internal HttpClientGenerator =
                     Accessibility = mem.Accessibility
                 }
             )
+            |> List.map (constructMember constantHeaders properties)
+
+        let propertyMembers =
+            properties
+            |> List.map (fun (_, pi) ->
+                SynMemberDefn.Member (
+                    SynBinding.SynBinding (
+                        pi.Accessibility,
+                        SynBindingKind.Normal,
+                        pi.IsInline,
+                        false,
+                        [],
+                        PreXmlDoc.Empty,
+                        SynValData.SynValData (
+                            Some
+                                {
+                                    IsInstance = true
+                                    IsDispatchSlot = false
+                                    IsOverrideOrExplicitImpl = true
+                                    IsFinal = false
+                                    GetterOrSetterIsCompilerGenerated = false
+                                    MemberKind = SynMemberKind.Member
+                                },
+                            SynValInfo.SynValInfo ([ [ SynArgInfo.Empty ] ; [] ], SynArgInfo.Empty),
+                            None
+                        ),
+                        SynPat.CreateLongIdent (
+                            SynLongIdent.CreateFromLongIdent [ Ident.Create "_" ; pi.Identifier ],
+                            []
+                        ),
+                        Some (SynBindingReturnInfo.Create pi.Type),
+                        SynExpr.CreateApp (
+                            SynExpr.CreateLongIdent (
+                                SynLongIdent.CreateFromLongIdent [ Ident.lowerFirstLetter pi.Identifier ]
+                            ),
+                            SynExpr.CreateConst SynConst.Unit
+                        ),
+                        range0,
+                        DebugPointAtBinding.Yes range0,
+                        {
+                            LeadingKeyword = SynLeadingKeyword.Member range0
+                            InlineKeyword = if pi.IsInline then Some range0 else None
+                            EqualsRange = Some range0
+                        }
+                    ),
+                    range0
+                )
+            )
+
+        let members = propertyMembers @ nonPropertyMembers
 
-        let constructed = members |> List.map constructMember
         let docString = PreXmlDoc.Create " Module for constructing a REST client."
 
         let interfaceImpl =
@@ -750,12 +967,35 @@ module internal HttpClientGenerator =
                 None,
                 Some range0,
                 [],
-                constructed,
+                members,
                 [],
                 range0,
                 range0
             )
 
+        let headerArgs =
+            properties
+            |> List.map (fun (_, pi) ->
+                SynPat.CreateTyped (
+                    SynPat.CreateNamed (Ident.lowerFirstLetter pi.Identifier),
+                    SynType.CreateFun (SynType.CreateLongIdent "unit", pi.Type)
+                )
+                |> SynPat.CreateParen
+            )
+
+        let clientCreationArg =
+            SynPat.CreateTyped (
+                SynPat.CreateNamed (Ident.Create "client"),
+                SynType.CreateLongIdent (SynLongIdent.Create [ "System" ; "Net" ; "Http" ; "HttpClient" ])
+            )
+            |> SynPat.CreateParen
+
+        let xmlDoc =
+            if properties.IsEmpty then
+                " Create a REST client."
+            else
+                " Create a REST client. The input functions will be re-evaluated on every HTTP request to obtain the required values for the corresponding header properties."
+
         let createFunc =
             SynBinding.SynBinding (
                 None,
@@ -763,7 +1003,7 @@ module internal HttpClientGenerator =
                 false,
                 false,
                 [],
-                PreXmlDoc.Create " Create a REST client.",
+                PreXmlDoc.Create xmlDoc,
                 SynValData.SynValData (
                     None,
                     SynValInfo.SynValInfo (
@@ -772,19 +1012,7 @@ module internal HttpClientGenerator =
                     ),
                     None
                 ),
-                SynPat.CreateLongIdent (
-                    SynLongIdent.CreateString "make",
-                    [
-                        SynPat.CreateParen (
-                            SynPat.CreateTyped (
-                                SynPat.CreateNamed (Ident.Create "client"),
-                                SynType.CreateLongIdent (
-                                    SynLongIdent.Create [ "System" ; "Net" ; "Http" ; "HttpClient" ]
-                                )
-                            )
-                        )
-                    ]
-                ),
+                SynPat.CreateLongIdent (SynLongIdent.CreateString "make", headerArgs @ [ clientCreationArg ]),
                 Some (
                     SynBindingReturnInfo.Create (
                         SynType.LongIdent (SynLongIdent.CreateFromLongIdent interfaceType.Name)
@@ -800,7 +1028,7 @@ module internal HttpClientGenerator =
 
         let moduleName : LongIdent =
             List.last interfaceType.Name
-            |> fun ident -> ident.idText
+            |> _.idText
             |> fun s ->
                 if s.StartsWith 'I' then
                     s.[1..]

WoofWare.Myriad.Plugins/Ident.fs

@@ -0,0 +1,14 @@
+namespace WoofWare.Myriad.Plugins
+
+open System
+open System.Text
+open Fantomas.FCS.Syntax
+open Myriad.Core
+
+[<RequireQualifiedAccess>]
+module internal Ident =
+    let lowerFirstLetter (x : Ident) : Ident =
+        let result = StringBuilder x.idText.Length
+        result.Append (Char.ToLowerInvariant x.idText.[0]) |> ignore
+        result.Append x.idText.[1..] |> ignore
+        Ident.Create ((result : StringBuilder).ToString ())

WoofWare.Myriad.Plugins/InterfaceMockGenerator.fs

@@ -6,13 +6,10 @@ open Fantomas.FCS.SyntaxTrivia
 open Fantomas.FCS.Xml
 open Myriad.Core
 
-/// Attribute indicating an interface type for which the "Generate Mock" Myriad
-/// generator should apply during build.
-/// This generator creates a record which implements the interface,
-/// but where each method is represented as a record field, so you can use
-/// record update syntax to easily specify partially-implemented mock objects.
-type GenerateMockAttribute () =
-    inherit Attribute ()
+type internal GenerateMockOutputSpec =
+    {
+        IsInternal : bool
+    }
 
 [<RequireQualifiedAccess>]
 module internal InterfaceMockGenerator =
@@ -24,13 +21,31 @@ module internal InterfaceMockGenerator =
         | None -> failwith "Expected record field to have a name, but it was somehow anonymous"
         | Some id -> id
 
+    [<RequireQualifiedAccess>]
+    type private KnownInheritance = | IDisposable
+
     let createType
+        (spec : GenerateMockOutputSpec)
         (name : string)
         (interfaceType : InterfaceType)
         (xmlDoc : PreXmlDoc)
         (fields : SynField list)
         : SynModuleDecl
         =
+        let inherits =
+            interfaceType.Inherits
+            |> Seq.map (fun ty ->
+                match ty with
+                | SynType.LongIdent (SynLongIdent.SynLongIdent (name, _, _)) ->
+                    match name |> List.map _.idText with
+                    | [] -> failwith "Unexpected empty identifier in inheritance declaration"
+                    | [ "IDisposable" ]
+                    | [ "System" ; "IDisposable" ] -> KnownInheritance.IDisposable
+                    | _ -> failwithf "Unrecognised inheritance identifier: %+A" name
+                | x -> failwithf "Unrecognised type in inheritance: %+A" x
+            )
+            |> Set.ofSeq
+
         let synValData =
             {
                 SynMemberFlags.IsInstance = false
@@ -92,6 +107,23 @@ module internal InterfaceMockGenerator =
                 )
             |> SynBindingReturnInfo.Create
 
+        let constructorFields =
+            let extras =
+                if inherits.Contains KnownInheritance.IDisposable then
+                    let unitFun = SynExpr.createLambda "_" SynExpr.CreateUnit
+
+                    [
+                        (SynLongIdent.CreateFromLongIdent [ Ident.Create "Dispose" ], true), Some unitFun
+                    ]
+                else
+                    []
+
+            let nonExtras =
+                fields
+                |> List.map (fun field -> (SynLongIdent.CreateFromLongIdent [ getName field ], true), Some failwithFun)
+
+            extras @ nonExtras
+
         let constructor =
             SynMemberDefn.Member (
                 SynBinding.SynBinding (
@@ -100,16 +132,11 @@ module internal InterfaceMockGenerator =
                     false,
                     false,
                     [],
-                    PreXmlDoc.Empty,
+                    PreXmlDoc.Create " An implementation where every method throws.",
                     SynValData.SynValData (Some synValData, SynValInfo.Empty, None),
                     constructorIdent,
                     Some constructorReturnType,
-                    AstHelper.instantiateRecord (
-                        fields
-                        |> List.map (fun field ->
-                            ((SynLongIdent.CreateFromLongIdent [ getName field ], true), Some failwithFun)
-                        )
-                    ),
+                    AstHelper.instantiateRecord constructorFields,
                     range0,
                     DebugPointAtBinding.Yes range0,
                     { SynExpr.synBindingTriviaZero true with
@@ -119,6 +146,21 @@ module internal InterfaceMockGenerator =
                 range0
             )
 
+        let fields =
+            let extras =
+                if inherits.Contains KnownInheritance.IDisposable then
+                    [
+                        SynField.Create (
+                            SynType.CreateFun (SynType.CreateUnit, SynType.CreateUnit),
+                            Ident.Create "Dispose",
+                            xmldoc = PreXmlDoc.Create " Implementation of IDisposable.Dispose"
+                        )
+                    ]
+                else
+                    []
+
+            extras @ fields
+
         let interfaceMembers =
             let members =
                 interfaceType.Members
@@ -152,7 +194,9 @@ module internal InterfaceMockGenerator =
                                                 |> List.mapi (fun i arg ->
                                                     arg.Args
                                                     |> List.mapi (fun j arg ->
-                                                        SynArgInfo.CreateIdString $"arg_%i{i}_%i{j}"
+                                                        match arg.Type with
+                                                        | UnitType -> SynArgInfo.SynArgInfo ([], false, None)
+                                                        | _ -> SynArgInfo.CreateIdString $"arg_%i{i}_%i{j}"
                                                     )
                                                 )
                                         ],
@@ -167,10 +211,18 @@ module internal InterfaceMockGenerator =
                         |> List.mapi (fun i tupledArgs ->
                             let args =
                                 tupledArgs.Args
-                                |> List.mapi (fun j _ -> SynPat.CreateNamed (Ident.Create $"arg_%i{i}_%i{j}"))
+                                |> List.mapi (fun j ty ->
+                                    match ty.Type with
+                                    | UnitType -> SynPat.Const (SynConst.Unit, range0)
+                                    | _ -> SynPat.CreateNamed (Ident.Create $"arg_%i{i}_%i{j}")
+                                )
 
-                            SynPat.Tuple (false, args, List.replicate (args.Length - 1) range0, range0)
-                            |> SynPat.CreateParen
+                            match args with
+                            | [] -> failwith "somehow got no args at all"
+                            | [ arg ] -> arg
+                            | args ->
+                                SynPat.Tuple (false, args, List.replicate (args.Length - 1) range0, range0)
+                                |> SynPat.CreateParen
                             |> fun i -> if tupledArgs.HasParen then SynPat.Paren (i, range0) else i
                         )
 
@@ -189,7 +241,11 @@ module internal InterfaceMockGenerator =
                             memberInfo.Args
                             |> List.mapi (fun i args ->
                                 args.Args
-                                |> List.mapi (fun j args -> SynExpr.CreateIdentString $"arg_%i{i}_%i{j}")
+                                |> List.mapi (fun j arg ->
+                                    match arg.Type with
+                                    | UnitType -> SynExpr.CreateConst SynConst.Unit
+                                    | _ -> SynExpr.CreateIdentString $"arg_%i{i}_%i{j}"
+                                )
                                 |> SynExpr.CreateParenedTuple
                             )
 
@@ -257,19 +313,109 @@ module internal InterfaceMockGenerator =
 
             SynMemberDefn.Interface (interfaceName, Some range0, Some members, range0)
 
-        // TODO: allow an arg to the attribute, specifying a custom visibility
         let access =
-            match interfaceType.Accessibility with
-            | Some (SynAccess.Public _)
-            | Some (SynAccess.Internal _)
-            | None -> SynAccess.Internal range0
-            | Some (SynAccess.Private _) -> SynAccess.Private range0
+            match interfaceType.Accessibility, spec.IsInternal with
+            | Some (SynAccess.Public _), true
+            | None, true -> SynAccess.Internal range0
+            | Some (SynAccess.Public _), false -> SynAccess.Public range0
+            | None, false -> SynAccess.Public range0
+            | Some (SynAccess.Internal _), _ -> SynAccess.Internal range0
+            | Some (SynAccess.Private _), _ -> SynAccess.Private range0
+
+        let extraInterfaces =
+            inherits
+            |> Seq.map (fun inheritance ->
+                match inheritance with
+                | KnownInheritance.IDisposable ->
+                    let valData =
+                        SynValData.SynValData (
+                            Some
+                                {
+                                    IsInstance = true
+                                    IsDispatchSlot = false
+                                    IsOverrideOrExplicitImpl = true
+                                    IsFinal = false
+                                    GetterOrSetterIsCompilerGenerated = false
+                                    MemberKind = SynMemberKind.Member
+                                },
+                            valInfo =
+                                SynValInfo.SynValInfo (
+                                    curriedArgInfos =
+                                        [
+                                            yield
+                                                [
+                                                    SynArgInfo.SynArgInfo (
+                                                        attributes = [],
+                                                        optional = false,
+                                                        ident = None
+                                                    )
+                                                ]
+                                        ],
+                                    returnInfo =
+                                        SynArgInfo.SynArgInfo (attributes = [], optional = false, ident = None)
+                                ),
+                            thisIdOpt = None
+                        )
+
+                    let headArgs = [ SynPat.Const (SynConst.Unit, range0) ]
+
+                    let headPat =
+                        SynPat.LongIdent (
+                            SynLongIdent.CreateFromLongIdent [ Ident.Create "this" ; Ident.Create "Dispose" ],
+                            None,
+                            None,
+                            SynArgPats.Pats headArgs,
+                            None,
+                            range0
+                        )
+
+                    let binding =
+                        SynBinding.SynBinding (
+                            None,
+                            SynBindingKind.Normal,
+                            false,
+                            false,
+                            [],
+                            PreXmlDoc.Empty,
+                            valData,
+                            headPat,
+                            Some (
+                                SynBindingReturnInfo.SynBindingReturnInfo (
+                                    SynType.Unit (),
+                                    range0,
+                                    [],
+                                    SynBindingReturnInfoTrivia.Zero
+                                )
+                            ),
+                            SynExpr.CreateApp (
+                                SynExpr.CreateLongIdent (SynLongIdent.Create [ "this" ; "Dispose" ]),
+                                SynExpr.CreateUnit
+                            ),
+                            range0,
+                            DebugPointAtBinding.Yes range0,
+                            {
+                                LeadingKeyword = SynLeadingKeyword.Member range0
+                                InlineKeyword = None
+                                EqualsRange = Some range0
+                            }
+                        )
+
+                    let mem = SynMemberDefn.Member (binding, range0)
+
+                    SynMemberDefn.Interface (
+                        SynType.CreateLongIdent (SynLongIdent.Create [ "System" ; "IDisposable" ]),
+                        Some range0,
+                        Some [ mem ],
+                        range0
+                    )
+            )
+            |> Seq.toList
 
         let record =
             {
                 Name = Ident.Create name
                 Fields = fields
-                Members = Some [ constructor ; interfaceMembers ]
+                Members = Some ([ constructor ; interfaceMembers ] @ extraInterfaces)
                 XmlDoc = Some xmlDoc
                 Generics = interfaceType.Generics
                 Accessibility = Some access
@@ -312,14 +458,19 @@ module internal InterfaceMockGenerator =
             SynFieldTrivia.Zero
         )
 
-    let createRecord (namespaceId : LongIdent) (interfaceType : SynTypeDefn) : SynModuleOrNamespace =
+    let createRecord
+        (namespaceId : LongIdent)
+        (opens : SynOpenDeclTarget list)
+        (interfaceType : SynTypeDefn, spec : GenerateMockOutputSpec)
+        : SynModuleOrNamespace
+        =
         let interfaceType = AstHelper.parseInterface interfaceType
         let fields = interfaceType.Members |> List.map constructMember
         let docString = PreXmlDoc.Create " Mock record type for an interface"
 
         let name =
             List.last interfaceType.Name
-            |> fun s -> s.idText
+            |> _.idText
             |> fun s ->
                 if s.StartsWith 'I' && s.Length > 1 && Char.IsUpper s.[1] then
                     s.[1..]
@@ -327,9 +478,12 @@ module internal InterfaceMockGenerator =
                     s
             |> fun s -> s + "Mock"
 
-        let typeDecl = createType name interfaceType docString fields
+        let typeDecl = createType spec name interfaceType docString fields
 
-        SynModuleOrNamespace.CreateNamespace (namespaceId, decls = [ typeDecl ])
+        SynModuleOrNamespace.CreateNamespace (
+            namespaceId,
+            decls = (opens |> List.map SynModuleDecl.CreateOpen) @ [ typeDecl ]
+        )
 
 /// Myriad generator that creates a record which implements the given interface,
 /// but with every field mocked out.
@@ -348,15 +502,37 @@ type InterfaceMockGenerator () =
             let namespaceAndInterfaces =
                 types
                 |> List.choose (fun (ns, types) ->
-                    match types |> List.filter Ast.hasAttribute<GenerateMockAttribute> with
-                    | [] -> None
-                    | types -> Some (ns, types)
+                    types
+                    |> List.choose (fun typeDef ->
+                        match Ast.getAttribute<GenerateMockAttribute> typeDef with
+                        | None -> None
+                        | Some attr ->
+                            let arg =
+                                match SynExpr.stripOptionalParen attr.ArgExpr with
+                                | SynExpr.Const (SynConst.Bool value, _) -> value
+                                | SynExpr.Const (SynConst.Unit, _) -> GenerateMockAttribute.DefaultIsInternal
+                                | arg ->
+                                    failwith
+                                        $"Unrecognised argument %+A{arg} to [<%s{nameof GenerateMockAttribute}>]. Literals are not supported. Use `true` or `false` (or unit) only."
+
+                            let spec =
+                                {
+                                    IsInternal = arg
+                                }
+
+                            Some (typeDef, spec)
+                    )
+                    |> function
+                        | [] -> None
+                        | ty -> Some (ns, ty)
                 )
 
             let opens = AstHelper.extractOpens ast
 
             let modules =
                 namespaceAndInterfaces
-                |> List.collect (fun (ns, records) -> records |> List.map (InterfaceMockGenerator.createRecord ns))
+                |> List.collect (fun (ns, records) ->
+                    records |> List.map (InterfaceMockGenerator.createRecord ns opens)
+                )
 
             Output.Ast modules

WoofWare.Myriad.Plugins/JsonParseGenerator.fs

@@ -7,23 +7,6 @@ open Fantomas.FCS.SyntaxTrivia
 open Fantomas.FCS.Xml
 open Myriad.Core
 
-/// Attribute indicating a record type to which the "Add JSON parse" Myriad
-/// generator should apply during build.
-/// The purpose of this generator is to create methods (possibly extension methods) of the form
-/// `{TypeName}.jsonParse : System.Text.Json.Nodes.JsonNode -> {TypeName}`.
-///
-/// If you supply isExtensionMethod = true, you will get extension methods.
-/// These can only be consumed from F#, but the benefit is that they don't use up the module name
-/// (since by default we create a module called "{TypeName}").
-type JsonParseAttribute (isExtensionMethod : bool) =
-    inherit Attribute ()
-
-    /// If changing this, *adjust the documentation strings*
-    static member internal DefaultIsExtensionMethod = false
-
-    /// Shorthand for the "isExtensionMethod = false" constructor; see documentation there for details.
-    new () = JsonParseAttribute JsonParseAttribute.DefaultIsExtensionMethod
-
 type internal JsonParseOutputSpec =
     {
         ExtensionMethods : bool
@@ -211,6 +194,12 @@ module internal JsonParseGenerator =
             node
             |> asValueGetValue propertyName "string"
             |> SynExpr.pipeThroughFunction (SynExpr.CreateLongIdent (SynLongIdent.Create [ "System" ; "Uri" ]))
+        | Guid ->
+            node
+            |> asValueGetValue propertyName "string"
+            |> SynExpr.pipeThroughFunction (
+                SynExpr.CreateLongIdent (SynLongIdent.Create [ "System" ; "Guid" ; "Parse" ])
+            )
         | DateTime ->
             node
             |> asValueGetValue propertyName "string"

WoofWare.Myriad.Plugins/JsonSerializeGenerator.fs

@@ -7,23 +7,6 @@ open Fantomas.FCS.SyntaxTrivia
 open Fantomas.FCS.Xml
 open Myriad.Core
 
-/// Attribute indicating a record type to which the "Add JSON serializer" Myriad
-/// generator should apply during build.
-/// The purpose of this generator is to create methods (possibly extension methods) of the form
-/// `{TypeName}.toJsonNode : {TypeName} -> System.Text.Json.Nodes.JsonNode`.
-///
-/// If you supply isExtensionMethod = true, you will get extension methods.
-/// These can only be consumed from F#, but the benefit is that they don't use up the module name
-/// (since by default we create a module called "{TypeName}").
-type JsonSerializeAttribute (isExtensionMethod : bool) =
-    inherit Attribute ()
-
-    /// If changing this, *adjust the documentation strings*
-    static member internal DefaultIsExtensionMethod = false
-
-    /// Shorthand for the "isExtensionMethod = false" constructor; see documentation there for details.
-    new () = JsonSerializeAttribute JsonSerializeAttribute.DefaultIsExtensionMethod
-
 type internal JsonSerializeOutputSpec =
     {
         ExtensionMethods : bool
@@ -43,8 +26,9 @@ module internal JsonSerializeGenerator =
         | DateTime
         | NumberType _
         | PrimitiveType _
+        | Guid
         | Uri ->
-            // JsonValue.Create<{type}>
+            // JsonValue.Create<type>
             SynExpr.TypeApp (
                 SynExpr.CreateLongIdent (
                     SynLongIdent.Create [ "System" ; "Text" ; "Json" ; "Nodes" ; "JsonValue" ; "Create" ]
@@ -64,11 +48,14 @@ module internal JsonSerializeGenerator =
                     SynMatchClause.Create (
                         SynPat.CreateLongIdent (SynLongIdent.CreateString "None", []),
                         None,
-                        SynExpr.CreateApp (
-                            SynExpr.CreateLongIdent (
-                                SynLongIdent.Create [ "System" ; "Text" ; "Json" ; "Nodes" ; "JsonValue" ; "Create" ]
-                            ),
-                            SynExpr.CreateNull
+                        // The absolutely galaxy-brained implementation of JsonValue has `JsonValue.Parse "null"`
+                        // identically equal to null. We have to work around this later, but we might as well just
+                        // be efficient here and whip up the null directly.
+                        SynExpr.CreateNull
+                        |> SynExpr.upcast' (
+                            SynType.CreateLongIdent (
+                                SynLongIdent.Create [ "System" ; "Text" ; "Json" ; "Nodes" ; "JsonNode" ]
+                            )
                         )
                     )
 
@@ -79,6 +66,12 @@ module internal JsonSerializeGenerator =
                         ),
                         None,
                         SynExpr.CreateApp (serializeNode ty, SynExpr.CreateIdentString "field")
+                        |> SynExpr.CreateParen
+                        |> SynExpr.upcast' (
+                            SynType.CreateLongIdent (
+                                SynLongIdent.Create [ "System" ; "Text" ; "Json" ; "Nodes" ; "JsonNode" ]
+                            )
+                        )
                     )
                 ]
             )

WoofWare.Myriad.Plugins/List.fs

@@ -0,0 +1,14 @@
+namespace WoofWare.Myriad.Plugins
+
+[<RequireQualifiedAccess>]
+module private List =
+    let partitionChoice<'a, 'b> (xs : Choice<'a, 'b> list) : 'a list * 'b list =
+        let xs, ys =
+            (([], []), xs)
+            ||> List.fold (fun (xs, ys) v ->
+                match v with
+                | Choice1Of2 x -> x :: xs, ys
+                | Choice2Of2 y -> xs, y :: ys
+            )
+
+        List.rev xs, List.rev ys

WoofWare.Myriad.Plugins/RemoveOptionsGenerator.fs

@@ -1,17 +1,10 @@
 namespace WoofWare.Myriad.Plugins
 
-open System
 open Fantomas.FCS.Syntax
 open Fantomas.FCS.SyntaxTrivia
 open Fantomas.FCS.Xml
 open Myriad.Core
 
-/// Attribute indicating a record type to which the "Remove Options" Myriad
-/// generator should apply during build.
-/// The purpose of this generator is to strip the `option` modifier from types.
-type RemoveOptionsAttribute () =
-    inherit Attribute ()
-
 [<RequireQualifiedAccess>]
 module internal RemoveOptionsGenerator =
     open Fantomas.FCS.Text.Range

WoofWare.Myriad.Plugins/SurfaceBaseline.txt

@@ -1,22 +1,12 @@
-WoofWare.Myriad.Plugins.GenerateMockAttribute inherit System.Attribute
-WoofWare.Myriad.Plugins.GenerateMockAttribute..ctor [constructor]: unit
-WoofWare.Myriad.Plugins.HttpClientAttribute inherit System.Attribute
-WoofWare.Myriad.Plugins.HttpClientAttribute..ctor [constructor]: unit
+WoofWare.Myriad.Plugins.CreateCatamorphismGenerator inherit obj, implements Myriad.Core.IMyriadGenerator
+WoofWare.Myriad.Plugins.CreateCatamorphismGenerator..ctor [constructor]: unit
 WoofWare.Myriad.Plugins.HttpClientGenerator inherit obj, implements Myriad.Core.IMyriadGenerator
 WoofWare.Myriad.Plugins.HttpClientGenerator..ctor [constructor]: unit
 WoofWare.Myriad.Plugins.InterfaceMockGenerator inherit obj, implements Myriad.Core.IMyriadGenerator
 WoofWare.Myriad.Plugins.InterfaceMockGenerator..ctor [constructor]: unit
-WoofWare.Myriad.Plugins.JsonParseAttribute inherit System.Attribute
-WoofWare.Myriad.Plugins.JsonParseAttribute..ctor [constructor]: bool
-WoofWare.Myriad.Plugins.JsonParseAttribute..ctor [constructor]: unit
 WoofWare.Myriad.Plugins.JsonParseGenerator inherit obj, implements Myriad.Core.IMyriadGenerator
 WoofWare.Myriad.Plugins.JsonParseGenerator..ctor [constructor]: unit
-WoofWare.Myriad.Plugins.JsonSerializeAttribute inherit System.Attribute
-WoofWare.Myriad.Plugins.JsonSerializeAttribute..ctor [constructor]: bool
-WoofWare.Myriad.Plugins.JsonSerializeAttribute..ctor [constructor]: unit
 WoofWare.Myriad.Plugins.JsonSerializeGenerator inherit obj, implements Myriad.Core.IMyriadGenerator
 WoofWare.Myriad.Plugins.JsonSerializeGenerator..ctor [constructor]: unit
-WoofWare.Myriad.Plugins.RemoveOptionsAttribute inherit System.Attribute
-WoofWare.Myriad.Plugins.RemoveOptionsAttribute..ctor [constructor]: unit
 WoofWare.Myriad.Plugins.RemoveOptionsGenerator inherit obj, implements Myriad.Core.IMyriadGenerator
 WoofWare.Myriad.Plugins.RemoveOptionsGenerator..ctor [constructor]: unit

WoofWare.Myriad.Plugins/SynExpr.fs

@@ -180,7 +180,7 @@ module internal SynExpr =
         SynExpr.CreateApp (SynExpr.CreateIdent (Ident.Create "reraise"), SynExpr.CreateConst SynConst.Unit)
 
     /// {body} |> fun a -> Async.StartAsTask (a, ?cancellationToken=ct)
-    let startAsTask (body : SynExpr) =
+    let startAsTask (ct : SynLongIdent) (body : SynExpr) =
         let lambda =
             SynExpr.CreateApp (
                 SynExpr.CreateLongIdent (SynLongIdent.Create [ "Async" ; "StartAsTask" ]),
@@ -189,7 +189,7 @@ module internal SynExpr =
                         SynExpr.CreateLongIdent (SynLongIdent.CreateString "a")
                         equals
                             (SynExpr.LongIdent (true, SynLongIdent.CreateString "cancellationToken", None, range0))
-                            (SynExpr.CreateLongIdent (SynLongIdent.CreateString "ct"))
+                            (SynExpr.CreateLongIdent ct)
                     ]
             )
             |> createLambda "a"
@@ -263,6 +263,8 @@ module internal SynExpr =
             |> callMethodArg "ToString" (SynExpr.CreateConstString "yyyy-MM-ddTHH:mm:ss")
         | _ -> callMethod "ToString" ident
 
+    let upcast' (ty : SynType) (e : SynExpr) = SynExpr.Upcast (e, ty, range0)
+
     let synBindingTriviaZero (isMember : bool) =
         {
             SynBindingTrivia.EqualsRange = Some range0
@@ -273,3 +275,55 @@ module internal SynExpr =
                 else
                     SynLeadingKeyword.Let range0
         }
+
+    /// {ident} - {rhs}
+    let minus (ident : SynLongIdent) (rhs : SynExpr) : SynExpr =
+        SynExpr.CreateApp (
+            SynExpr.CreateAppInfix (
+                SynExpr.CreateLongIdent (
+                    SynLongIdent.SynLongIdent (
+                        [ Ident.Create "op_Subtraction" ],
+                        [],
+                        [ Some (IdentTrivia.OriginalNotation "-") ]
+                    )
+                ),
+                SynExpr.CreateLongIdent ident
+            ),
+            rhs
+        )
+
+    /// {ident} - {n}
+    let minusN (ident : SynLongIdent) (n : int) : SynExpr =
+        minus ident (SynExpr.CreateConst (SynConst.Int32 n))
+
+    /// {y} > {x}
+    let greaterThan (x : SynExpr) (y : SynExpr) : SynExpr =
+        SynExpr.CreateApp (
+            SynExpr.CreateAppInfix (
+                SynExpr.CreateLongIdent (
+                    SynLongIdent.SynLongIdent (
+                        [ Ident.Create "op_GreaterThan" ],
+                        [],
+                        [ Some (IdentTrivia.OriginalNotation ">") ]
+                    )
+                ),
+                y
+            ),
+            x
+        )
+
+    /// {y} >= {x}
+    let greaterThanOrEqual (x : SynExpr) (y : SynExpr) : SynExpr =
+        SynExpr.CreateApp (
+            SynExpr.CreateAppInfix (
+                SynExpr.CreateLongIdent (
+                    SynLongIdent.SynLongIdent (
+                        [ Ident.Create "op_GreaterThanOrEqual" ],
+                        [],
+                        [ Some (IdentTrivia.OriginalNotation ">=") ]
+                    )
+                ),
+                y
+            ),
+            x
+        )

WoofWare.Myriad.Plugins/WoofWare.Myriad.Plugins.fsproj

@@ -18,21 +18,24 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Myriad.Core" Version="0.8.3"/>
+    <PackageReference Include="Myriad.Core" Version="0.8.3" PrivateAssets="all"/>
     <!-- the lowest version allowed by Myriad.Core -->
-    <PackageReference Update="FSharp.Core" Version="6.0.1"/>
+    <PackageReference Update="FSharp.Core" Version="6.0.1" PrivateAssets="all"/>
   </ItemGroup>
 
   <ItemGroup>
+    <Compile Include="List.fs"/>
+    <Compile Include="Ident.fs" />
     <Compile Include="AstHelper.fs"/>
     <Compile Include="SynExpr.fs"/>
-    <Compile Include="SynType.fs" />
+    <Compile Include="SynType.fs"/>
     <Compile Include="SynAttribute.fs"/>
     <Compile Include="RemoveOptionsGenerator.fs"/>
-    <Compile Include="InterfaceMockGenerator.fs" />
-    <Compile Include="JsonSerializeGenerator.fs" />
+    <Compile Include="InterfaceMockGenerator.fs"/>
+    <Compile Include="JsonSerializeGenerator.fs"/>
     <Compile Include="JsonParseGenerator.fs"/>
     <Compile Include="HttpClientGenerator.fs"/>
+    <Compile Include="CataGenerator.fs" />
     <EmbeddedResource Include="version.json"/>
     <EmbeddedResource Include="SurfaceBaseline.txt"/>
     <None Include="..\README.md">
@@ -45,4 +48,11 @@
     </None>
   </ItemGroup>
 
+  <ItemGroup>
+    <ProjectReference Include="..\WoofWare.Myriad.Plugins.Attributes\WoofWare.Myriad.Plugins.Attributes.fsproj"/>
+    <!-- NuGet is such a clown package manager! Get the DLLs into the Nupkg artefact, I have no idea why this is needed,
+         but without this line, we don't get any dependency at all packaged into the resulting artefact. -->
+    <None Include="$(OutputPath)\WoofWare.Myriad.Plugins.Attributes.dll" Pack="true" PackagePath="lib\$(TargetFramework)"/>
+  </ItemGroup>
+
 </Project>

WoofWare.Myriad.Plugins/version.json

@@ -1,5 +1,5 @@
 {
-  "version": "1.4",
+  "version": "2.1",
   "publicReleaseRefSpec": [
     "^refs/heads/main$"
   ],

WoofWare.Myriad.sln

@@ -6,6 +6,10 @@ Project("{F2A71F9B-5D33-465A-A702-920D77279786}") = "WoofWare.Myriad.Plugins", "
 EndProject
 Project("{F2A71F9B-5D33-465A-A702-920D77279786}") = "WoofWare.Myriad.Plugins.Test", "WoofWare.Myriad.Plugins.Test\WoofWare.Myriad.Plugins.Test.fsproj", "{EBFFA5D3-7F74-4824-8795-B6194E6FE0CB}"
 EndProject
+Project("{F2A71F9B-5D33-465A-A702-920D77279786}") = "WoofWare.Myriad.Plugins.Attributes", "WoofWare.Myriad.Plugins.Attributes\WoofWare.Myriad.Plugins.Attributes.fsproj", "{17548737-9BAB-4B1E-B680-76D47C343AAC}"
+EndProject
+Project("{F2A71F9B-5D33-465A-A702-920D77279786}") = "WoofWare.Myriad.Plugins.Attributes.Test", "WoofWare.Myriad.Plugins.Attributes\Test\WoofWare.Myriad.Plugins.Attributes.Test.fsproj", "{26DC0C94-85F2-45B4-8FA1-1B27201F7AFB}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -24,5 +28,13 @@ Global
 		{EBFFA5D3-7F74-4824-8795-B6194E6FE0CB}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{EBFFA5D3-7F74-4824-8795-B6194E6FE0CB}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{EBFFA5D3-7F74-4824-8795-B6194E6FE0CB}.Release|Any CPU.Build.0 = Release|Any CPU
+		{17548737-9BAB-4B1E-B680-76D47C343AAC}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{17548737-9BAB-4B1E-B680-76D47C343AAC}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{17548737-9BAB-4B1E-B680-76D47C343AAC}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{17548737-9BAB-4B1E-B680-76D47C343AAC}.Release|Any CPU.Build.0 = Release|Any CPU
+		{26DC0C94-85F2-45B4-8FA1-1B27201F7AFB}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{26DC0C94-85F2-45B4-8FA1-1B27201F7AFB}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{26DC0C94-85F2-45B4-8FA1-1B27201F7AFB}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{26DC0C94-85F2-45B4-8FA1-1B27201F7AFB}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 EndGlobal

analyzers/analyzers.fsproj

@@ -10,7 +10,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageDownload Include="G-Research.FSharp.Analyzers" Version="[0.6.0]" />
+    <PackageDownload Include="G-Research.FSharp.Analyzers" Version="[0.9.3]" />
   </ItemGroup>
 
 </Project>

flake.nix

@@ -44,8 +44,8 @@
         };
     in {
       packages = {
-        fantomas = dotnetTool null "fantomas" (builtins.fromJSON (builtins.readFile ./.config/dotnet-tools.json)).tools.fantomas.version "sha256-Jmo7s8JMdQ8SxvNvPnryfE7n24mIgKi5cbgNwcQw3yU=";
-        fsharp-analyzers = dotnetTool "FSharp.Analyzers.Cli" "fsharp-analyzers" (builtins.fromJSON (builtins.readFile ./.config/dotnet-tools.json)).tools.fsharp-analyzers.version "sha256-CWMW06ncSs8QkQvxNPNrgn3TAzMU6qCT1k2A3pnGrYQ=";
+        fantomas = dotnetTool null "fantomas" (builtins.fromJSON (builtins.readFile ./.config/dotnet-tools.json)).tools.fantomas.version (builtins.head (builtins.filter (elem: elem.pname == "fantomas") ((import ./nix/deps.nix) {fetchNuGet = x: x;}))).sha256;
+        fsharp-analyzers = dotnetTool "FSharp.Analyzers.Cli" "fsharp-analyzers" (builtins.fromJSON (builtins.readFile ./.config/dotnet-tools.json)).tools.fsharp-analyzers.version (builtins.head (builtins.filter (elem: elem.pname == "fsharp-analyzers") ((import ./nix/deps.nix) {fetchNuGet = x: x;}))).sha256;
         fetchDeps = let
           flags = [];
           runtimeIds = ["win-x64"] ++ map (system: pkgs.dotnetCorePackages.systemToDotnetRid system) dotnet-sdk.meta.platforms;
@@ -54,8 +54,8 @@
             src = ./nix/fetchDeps.sh;
             pname = pname;
             binPath = pkgs.lib.makeBinPath [pkgs.coreutils dotnet-sdk (pkgs.nuget-to-nix.override {inherit dotnet-sdk;})];
-            projectFiles = toString ["./WoofWare.Myriad.Plugins/WoofWare.Myriad.Plugins.fsproj" "./ConsumePlugin/ConsumePlugin.fsproj"];
-            testProjectFiles = ["./WoofWare.Myriad.Plugins.Test/WoofWare.Myriad.Plugins.Test.fsproj"];
+            projectFiles = toString ["./WoofWare.Myriad.Plugins/WoofWare.Myriad.Plugins.fsproj" "./ConsumePlugin/ConsumePlugin.fsproj" "./WoofWare.Myriad.Plugins.Attributes/WoofWare.Myriad.Plugins.Attributes.fsproj"];
+            testProjectFiles = ["./WoofWare.Myriad.Plugins.Test/WoofWare.Myriad.Plugins.Test.fsproj" "./WoofWare.Myriad.Plugins.Attributes/Test/Woofware.Myriad.Plugins.Attributes.Test.fsproj"];
             rids = pkgs.lib.concatStringsSep "\" \"" runtimeIds;
             packages = dotnet-sdk.packages;
             storeSrc = pkgs.srcOnly {

nix/deps.nix

@@ -3,23 +3,18 @@
 {fetchNuGet}: [
   (fetchNuGet {
     pname = "fsharp-analyzers";
-    version = "0.23.0";
-    sha256 = "sha256-CWMW06ncSs8QkQvxNPNrgn3TAzMU6qCT1k2A3pnGrYQ=";
+    version = "0.25.0";
+    sha256 = "sha256-njfJYi40jNvrD+mgu9LtQw2Omh8P1SSDThesozH0KQY=";
   })
   (fetchNuGet {
     pname = "fantomas";
-    version = "6.3.0-alpha-005";
-    sha256 = "sha256-Jmo7s8JMdQ8SxvNvPnryfE7n24mIgKi5cbgNwcQw3yU=";
+    version = "6.3.4";
+    sha256 = "sha256-1aWqZynBkQoznenGoP0sbf1PcUXAbcHiWyECuv89xa0=";
   })
   (fetchNuGet {
     pname = "ApiSurface";
-    version = "4.0.25";
-    sha256 = "0zjq8an9cr0l7wxdmm9n9s3iyq5m0zl4x0h0wmy5cz7am8y15qc4";
-  })
-  (fetchNuGet {
-    pname = "coverlet.collector";
-    version = "6.0.0";
-    sha256 = "12j34vrkmph8lspbafnqmfnj2qvysz1jcrks2khw798s6dwv0j90";
+    version = "4.0.39";
+    sha256 = "sha256-I4K5nJbltsfL/1r+KPTIo2wUd30zsCC2pkrnIRnsRHM=";
   })
   (fetchNuGet {
     pname = "Fantomas.Core";
@@ -36,6 +31,11 @@
     version = "2.16.6";
     sha256 = "176rwky6b5rk8dzldiz4068p7m9c5y9ygzbhadrs14jkl94pc56n";
   })
+  (fetchNuGet {
+    pname = "FSharp.Core";
+    version = "4.3.4";
+    sha256 = "1sg6i4q5nwyzh769g76f6c16876nvdpn83adqjr2y9x6xsiv5p5j";
+  })
   (fetchNuGet {
     pname = "FSharp.Core";
     version = "6.0.1";
@@ -118,13 +118,13 @@
   })
   (fetchNuGet {
     pname = "Microsoft.CodeCoverage";
-    version = "17.8.0";
-    sha256 = "173wjadp3gan4x2jfjchngnc4ca4mb95h1sbb28jydfkfw0z1zvj";
+    version = "17.9.0";
+    sha256 = "1gljgi69k0fz8vy8bn6xlyxabj6q4vls2zza9wz7ng6ix3irm89r";
   })
   (fetchNuGet {
     pname = "Microsoft.NET.Test.Sdk";
-    version = "17.8.0";
-    sha256 = "1syvl3g0hbrcgfi9rq6pld8s8hqqww4dflf1lxn59ccddyyx0gmv";
+    version = "17.9.0";
+    sha256 = "1lls1fly2gr1n9n1xyl9k33l2v4pwfmylyzkq8v4v5ldnwkl1zdb";
   })
   (fetchNuGet {
     pname = "Microsoft.NETCore.App.Host.linux-arm64";
@@ -236,6 +236,11 @@
     version = "8.0.1";
     sha256 = "198576cdkl72xs29zznff9ls763p8pfr0zji7b74dqxd5ga0s3bd";
   })
+  (fetchNuGet {
+    pname = "Microsoft.NETCore.Platforms";
+    version = "1.1.0";
+    sha256 = "08vh1r12g6ykjygq5d3vq09zylgb84l63k49jc4v8faw9g93iqqm";
+  })
   (fetchNuGet {
     pname = "Microsoft.NETCore.Platforms";
     version = "1.1.1";
@@ -263,13 +268,13 @@
   })
   (fetchNuGet {
     pname = "Microsoft.TestPlatform.ObjectModel";
-    version = "17.8.0";
-    sha256 = "0b0i7lmkrcfvim8i3l93gwqvkhhhfzd53fqfnygdqvkg6np0cg7m";
+    version = "17.9.0";
+    sha256 = "1kgsl9w9fganbm9wvlkqgk0ag9hfi58z88rkfybc6kvg78bx89ca";
   })
   (fetchNuGet {
     pname = "Microsoft.TestPlatform.TestHost";
-    version = "17.8.0";
-    sha256 = "0f5jah93kjkvxwmhwb78lw11m9pkkq9fvf135hpymmmpxqbdh97q";
+    version = "17.9.0";
+    sha256 = "19ffh31a1jxzn8j69m1vnk5hyfz3dbxmflq77b8x82zybiilh5nl";
   })
   (fetchNuGet {
     pname = "Myriad.Core";
@@ -286,6 +291,11 @@
     version = "3.6.133";
     sha256 = "1cdw8krvsnx0n34f7fm5hiiy7bs6h3asvncqcikc0g46l50w2j80";
   })
+  (fetchNuGet {
+    pname = "NETStandard.Library";
+    version = "2.0.3";
+    sha256 = "1fn9fxppfcg4jgypp2pmrpr6awl3qz1xmnri0cygpkwvyx27df1y";
+  })
   (fetchNuGet {
     pname = "Newtonsoft.Json";
     version = "13.0.1";
@@ -298,28 +308,23 @@
   })
   (fetchNuGet {
     pname = "NuGet.Common";
-    version = "6.8.0";
-    sha256 = "0l3ij8iwy7wj6s7f93lzi9168r4wz8zyin6a08iwgk7hvq44cia1";
+    version = "6.9.1";
+    sha256 = "0ic3d46r9v05pkczpmskw86yzixm6iwshbw0ya8i2957nhhlymw8";
   })
   (fetchNuGet {
     pname = "NuGet.Configuration";
-    version = "6.8.0";
-    sha256 = "0x03p408smkmv1gv7pmvsia4lkn0xaj4wfrkl58pjf8bbv51y0yw";
+    version = "6.9.1";
+    sha256 = "07z4qgbibpg59j2r05ifnqdyqf2xinm33rx7gjyr1f73kzg01m33";
   })
   (fetchNuGet {
     pname = "NuGet.Frameworks";
-    version = "6.5.0";
-    sha256 = "0s37d1p4md0k6d4cy6sq36f2dgkd9qfbzapxhkvi8awwh0vrynhj";
-  })
-  (fetchNuGet {
-    pname = "NuGet.Frameworks";
-    version = "6.8.0";
-    sha256 = "0i2xvhgkjkjr496i3pg8hamwv6505fia45qhn7jg5m01wb3cvsjl";
+    version = "6.9.1";
+    sha256 = "0s3az3ac53icjnmb14hfjcmkvzscvrkm62jgqf48yvsbysyhqm5s";
   })
   (fetchNuGet {
     pname = "NuGet.Packaging";
-    version = "6.8.0";
-    sha256 = "031z4s905bxi94h3f0qy4j1b6jxdxgqgpkzqvvpfxch07szxcbim";
+    version = "6.9.1";
+    sha256 = "0w0arkmzg3qh1brq4vm10zrsjm7nw706ld4y5kqcmvjpd16f4b4y";
   })
   (fetchNuGet {
     pname = "NuGet.Protocol";
@@ -328,18 +333,13 @@
   })
   (fetchNuGet {
     pname = "NuGet.Versioning";
-    version = "6.8.0";
-    sha256 = "1sd25h46fd12ng780r02q4ijcx1imkb53kj1y2y7cwg5myh537ks";
+    version = "6.9.1";
+    sha256 = "0xrs82dydy9cgxf0qypr01wawwnq1nf6fc7rwisb4y5v4r259fdm";
   })
   (fetchNuGet {
     pname = "NUnit";
-    version = "4.0.1";
-    sha256 = "0jgiq3dbwli5r70j0bw7021d69r7bhr58s8kphlpjmf7k47l5pcd";
-  })
-  (fetchNuGet {
-    pname = "NUnit.Analyzers";
-    version = "3.10.0";
-    sha256 = "1zc6s7lmzw5avrnbbjwyzla9d6bafbpxgv62m4zlqxv14p85md0d";
+    version = "4.1.0";
+    sha256 = "0fj6xwgqaxq3mrai86bklclfmjkzf038mrslwfqf4ignaz9f7g5j";
   })
   (fetchNuGet {
     pname = "NUnit3TestAdapter";