Add no-attribute support for CreateCatamorphism (#461)

* Bump WoofWare.Expect from 0.8.4 to 0.8.5

---
updated-dependencies:
- dependency-name: WoofWare.Expect
  dependency-version: 0.8.5
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

* 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

@@ -9,10 +9,16 @@
       ]
     },
     "fsharp-analyzers": {
-      "version": "0.33.1",
+      "version": "0.34.1",
       "commands": [
         "fsharp-analyzers"
       ]
+    },
+    "woofware.nunittestrunner": {
+      "version": "0.3.9",
+      "commands": [
+        "woofware.nunittestrunner"
+      ]
     }
   }
 }

.github/workflows/dotnet.yaml

@@ -25,7 +25,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v6
       with:
         fetch-depth: 0 # so that NerdBank.GitVersioning has access to history
     - name: Install Nix
@@ -46,7 +46,7 @@ jobs:
       security-events: write
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           fetch-depth: 0 # so that NerdBank.GitVersioning has access to history
       - name: Install Nix
@@ -65,7 +65,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
       - name: Install Nix
         uses: cachix/install-nix-action@v31
         with:
@@ -80,7 +80,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
       - name: Install Nix
         uses: cachix/install-nix-action@v31
         with:
@@ -93,7 +93,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           fetch-depth: 0 # so that NerdBank.GitVersioning has access to history
       - name: Install Nix
@@ -114,7 +114,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
       - name: Install Nix
         uses: cachix/install-nix-action@v31
         with:
@@ -152,7 +152,7 @@ jobs:
   nuget-pack:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v6
       with:
         fetch-depth: 0 # so that NerdBank.GitVersioning has access to history
     - name: Install Nix
@@ -207,7 +207,7 @@ jobs:
     runs-on: ubuntu-latest
     needs: [nuget-pack]
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Download NuGet artifact
         uses: actions/download-artifact@v6
         with:
@@ -287,7 +287,7 @@ jobs:
       attestations: write
       contents: read
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Install Nix
         uses: cachix/install-nix-action@v31
         with:
@@ -325,7 +325,7 @@ jobs:
       attestations: write
       contents: read
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Install Nix
         uses: cachix/install-nix-action@v31
         with:
@@ -366,7 +366,7 @@ jobs:
     permissions:
       contents: write
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Download NuGet artifact
         uses: actions/download-artifact@v6
         with:

.github/workflows/flake_update.yaml

@@ -11,7 +11,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Check out repository
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Install Nix
         uses: DeterminateSystems/nix-installer-action@main

CHANGELOG.md

@@ -1,5 +1,16 @@
 Notable changes are recorded here.
 
+# WoofWare.Myriad.Plugins 9.1.1, WoofWare.Myriad.Plugins.Attributes 3.8.1
+
+Adds the `[<ArgumentNegateWithPrefix>]` attribute, which can be placed on a boolean or flag-valued field when using the `ArgParser` generator.
+This causes the boolean to be specifiable with the `--no-` prefix to negate its value.
+(For example, `Foo : bool` is normally specified as `--foo`; this new attribute lets the user additionally give `--no-foo` to get the same semantics as `--foo=false`.)
+
+# WoofWare.Myriad.Plugins 9.0.1
+
+Converts the `static member Empty` field on each generated mock (from `GeneratedMock`) into a function, so as to permit the `GeneratedCapturingMock` to have the same signature.
+(`GeneratedCapturingMock` contains mutable state, so must be created afresh each time.)
+
 # WoofWare.Myriad.Plugins 8.1.1
 
 Adds `GenerateCapturingMock`, which is `GenerateMock` but additionally records the calls made to each function.

ConsumePlugin/ArgParserConflictTests.fs

@@ -0,0 +1,124 @@
+namespace ConsumePlugin
+
+open WoofWare.Myriad.Plugins
+
+// This file contains test cases for conflict detection in the ArgParser generator.
+// These are expected to FAIL at build time with appropriate error messages.
+// Uncomment each section one at a time to test the specific conflict detection.
+
+// ============================================================================
+// Test 1: Field named NoFooBar conflicts with FooBar's --no- variant
+// ============================================================================
+// Expected error: Argument name conflict: '--no-foo-bar' collides with the --no- variant
+// of field 'FooBar' (which has [<ArgumentNegateWithPrefix>])
+
+(*
+[<ArgParser>]
+type ConflictingFieldNames =
+    {
+        [<ArgumentNegateWithPrefix>]
+        FooBar : bool
+        NoFooBar : bool
+    }
+*)
+
+// ============================================================================
+// Test 2: ArgumentLongForm "no-foo" conflicts with Foo's --no- variant
+// ============================================================================
+// Expected error: Argument name conflict: '--no-foo' collides with the --no- variant
+// of field 'Foo' (which has [<ArgumentNegateWithPrefix>])
+
+(*
+[<ArgParser>]
+type ConflictingLongForm =
+    {
+        [<ArgumentNegateWithPrefix>]
+        Foo : bool
+        [<ArgumentLongForm "no-foo">]
+        Bar : bool
+    }
+*)
+
+// ============================================================================
+// Test 3: Multiple ArgumentLongForm, one conflicts
+// ============================================================================
+// Expected error: Argument name conflict: '--no-verbose' collides with...
+
+(*
+[<ArgParser>]
+type ConflictingMultipleLongForms =
+    {
+        [<ArgumentLongForm "verbose">]
+        [<ArgumentLongForm "v">]
+        [<ArgumentNegateWithPrefix>]
+        VerboseMode : bool
+
+        [<ArgumentLongForm "no-verbose">]
+        Quiet : bool
+    }
+*)
+
+// ============================================================================
+// Test 4: ArgumentNegateWithPrefix on non-boolean field
+// ============================================================================
+// Expected error: [<ArgumentNegateWithPrefix>] can only be applied to boolean
+// or flag DU fields, but was applied to field NotABool of type string
+
+(*
+[<ArgParser>]
+type InvalidAttributeOnNonBool =
+    {
+        [<ArgumentNegateWithPrefix>]
+        NotABool : string
+    }
+*)
+
+// ============================================================================
+// Test 5: ArgumentNegateWithPrefix on non-flag int field
+// ============================================================================
+// Expected error: [<ArgumentNegateWithPrefix>] can only be applied to boolean
+// or flag DU fields
+
+(*
+[<ArgParser>]
+type InvalidAttributeOnInt =
+    {
+        [<ArgumentNegateWithPrefix>]
+        NotAFlag : int
+    }
+*)
+
+// ============================================================================
+// Test 6: Complex conflict with custom names
+// ============================================================================
+// This tests a more complex scenario where a custom ArgumentLongForm creates
+// a conflict with a different field's negated form
+
+(*
+[<ArgParser>]
+type ComplexConflict =
+    {
+        [<ArgumentLongForm "enable">]
+        [<ArgumentNegateWithPrefix>]
+        FeatureA : bool
+
+        [<ArgumentLongForm "no-enable">]
+        DisableAll : bool
+    }
+*)
+
+// ============================================================================
+// Test 7: Valid usage - no conflicts (this SHOULD compile)
+// ============================================================================
+
+[<ArgParser>]
+type NoConflict =
+    {
+        [<ArgumentNegateWithPrefix>]
+        EnableFeature : bool
+
+        [<ArgumentNegateWithPrefix>]
+        VerboseMode : bool
+
+        NormalField : string
+    }

ConsumePlugin/ArgParserNegationTests.fs

@@ -0,0 +1,48 @@
+namespace ConsumePlugin
+
+open WoofWare.Myriad.Plugins
+
+// Test types for ArgumentNegateWithPrefix functionality
+
+type TestDryRunMode =
+    | [<ArgumentFlag false>] Wet
+    | [<ArgumentFlag true>] Dry
+
+[<ArgParser true>]
+type BoolNegation =
+    {
+        [<ArgumentNegateWithPrefix>]
+        EnableFeature : bool
+    }
+
+[<ArgParser true>]
+type FlagNegation =
+    {
+        [<ArgumentNegateWithPrefix>]
+        DryRun : TestDryRunMode
+    }
+
+[<ArgParser true>]
+type MultipleFormsNegation =
+    {
+        [<ArgumentLongForm "verbose">]
+        [<ArgumentLongForm "v">]
+        [<ArgumentNegateWithPrefix>]
+        VerboseMode : bool
+    }
+
+[<ArgParser true>]
+type CombinedFeatures =
+    {
+        [<ArgumentNegateWithPrefix>]
+        [<ArgumentDefaultFunction>]
+        Verbose : Choice<bool, bool>
+
+        [<ArgumentNegateWithPrefix>]
+        [<ArgumentHelpText "Enable debug mode">]
+        Debug : bool
+
+        NormalBool : bool
+    }
+
+    static member DefaultVerbose () = false

ConsumePlugin/Args.fs

@@ -235,3 +235,27 @@ type FlagsIntoPositionalArgs' =
         [<PositionalArgs false>]
         DontGrabEverything : string list
     }
+
+[<ArgParser>]
+[<ArgumentHelpText "Parse command-line arguments for a basic configuration. This help text appears before the argument list.">]
+type WithTypeHelp =
+    {
+        [<ArgumentHelpText "The configuration file path">]
+        ConfigFile : string
+        [<ArgumentHelpText "Enable verbose output">]
+        Verbose : bool
+        Port : int
+    }
+
+[<ArgParser>]
+[<ArgumentHelpText "This is a multiline help text example.
+It spans multiple lines to test that multiline strings work correctly.
+You can use this to provide detailed documentation for your argument parser.">]
+type WithMultilineTypeHelp =
+    {
+        [<ArgumentHelpText "Input file to process">]
+        InputFile : string
+        [<ArgumentHelpText "Output directory">]
+        OutputDir : string
+        Force : bool
+    }

ConsumePlugin/CapturingMockExample.fs

@@ -55,3 +55,15 @@ type TypeWithProperties =
     abstract Mem1 : string option -> string[] Async
     abstract Prop1 : int
     abstract Prop2 : unit Async
+
+[<GenerateCapturingMock>]
+type TypeWithAsyncDisposable =
+    inherit IAsyncDisposable
+    abstract Mem1 : string option -> string[] Async
+    abstract Mem2 : unit -> string[] Async
+
+[<GenerateCapturingMock>]
+type TypeWithBothDisposables =
+    inherit IDisposable
+    inherit IAsyncDisposable
+    abstract Mem1 : string -> int

ConsumePlugin/CatamorphismNoAttribute.fs

@@ -0,0 +1,19 @@
+namespace ConsumePluginNoAttr
+
+type ConstNoAttr<'a> =
+    | Verbatim of 'a
+    | String of string
+
+type PairOpKindNoAttr =
+    | NormalSeq
+    | ThenDoSeq
+
+type TreeNoAttr<'a, 'b> =
+    | Const of ConstNoAttr<'a> * 'b
+    | Pair of TreeNoAttr<'a, 'b> * TreeNoAttr<'a, 'b> * PairOpKindNoAttr
+    | Sequential of TreeNoAttr<'a, 'b> list
+    | Builder of TreeNoAttr<'a, 'b> * TreeBuilderNoAttr<'b, 'a>
+
+and TreeBuilderNoAttr<'b, 'a> =
+    | Child of TreeBuilderNoAttr<'b, 'a>
+    | Parent of TreeNoAttr<'a, 'b>

ConsumePlugin/ConsumePlugin.fsproj

@@ -77,6 +77,13 @@
     <Compile Include="GeneratedCatamorphism.fs">
       <MyriadFile>Catamorphism.fs</MyriadFile>
     </Compile>
+    <Compile Include="CatamorphismNoAttribute.fs" />
+    <Compile Include="GeneratedCatamorphismNoAttribute.fs">
+      <MyriadFile>CatamorphismNoAttribute.fs</MyriadFile>
+      <MyriadParams>
+        <TreeNoAttr>CreateCatamorphism(TreeNoAttrCata)</TreeNoAttr>
+      </MyriadParams>
+    </Compile>
     <Compile Include="FSharpForFunAndProfitCata.fs" />
     <Compile Include="GeneratedFileSystem.fs">
       <MyriadFile>FSharpForFunAndProfitCata.fs</MyriadFile>
@@ -89,6 +96,17 @@
     <Compile Include="GeneratedArgs.fs">
       <MyriadFile>Args.fs</MyriadFile>
     </Compile>
+    <Compile Include="ArgParserNegationTests.fs" />
+    <Compile Include="GeneratedArgParserNegationTests.fs">
+      <MyriadFile>ArgParserNegationTests.fs</MyriadFile>
+    </Compile>
+    <!-- Not compiled, because by design they *don't* compile. That makes them very hard to test in an automated way! -->
+    <None Include="ArgParserConflictTests.fs" />
+    <!-- To run the conflict tests:
+    <Compile Include="GeneratedArgParserConflictTests.fs">
+      <MyriadFile>ArgParserConflictTests.fs</MyriadFile>
+    </Compile>
+    -->
     <None Include="swagger-gitea.json" />
     <Compile Include="GeneratedSwaggerGitea.fs">
       <MyriadFile>swagger-gitea.json</MyriadFile>

ConsumePlugin/GeneratedArgs.fs

@@ -4346,3 +4346,438 @@ module FlagsIntoPositionalArgs'ArgParse =
 
         static member parse (args : string list) : FlagsIntoPositionalArgs' =
             FlagsIntoPositionalArgs'.parse' (System.Environment.GetEnvironmentVariable >> Option.ofObj) args
+namespace ConsumePlugin
+
+open System
+open System.IO
+open WoofWare.Myriad.Plugins
+
+/// Methods to parse arguments for the type WithTypeHelp
+[<RequireQualifiedAccess ; CompilationRepresentation(CompilationRepresentationFlags.ModuleSuffix)>]
+module WithTypeHelp =
+    type private ParseState_WithTypeHelp =
+        /// Ready to consume a key or positional arg
+        | AwaitingKey
+        /// Waiting to receive a value for the key we've already consumed
+        | AwaitingValue of key : string
+
+    let parse' (getEnvironmentVariable : string -> string option) (args : string list) : WithTypeHelp =
+        let ArgParser_errors = ResizeArray ()
+
+        let helpText () =
+            [
+                "Parse command-line arguments for a basic configuration. This help text appears before the argument list."
+                ""
+
+                (sprintf
+                    "%s  string%s%s"
+                    (sprintf "--%s" "config-file")
+                    ""
+                    (sprintf " : %s" ("The configuration file path")))
+
+                (sprintf "%s  bool%s%s" (sprintf "--%s" "verbose") "" (sprintf " : %s" ("Enable verbose output")))
+                (sprintf "%s  int32%s%s" (sprintf "--%s" "port") "" "")
+            ]
+            |> String.concat "\n"
+
+        let parser_LeftoverArgs : string ResizeArray = ResizeArray ()
+        let mutable arg_0 : string option = None
+        let mutable arg_1 : bool option = None
+        let mutable arg_2 : int option = None
+
+        /// Processes the key-value pair, returning Error if no key was matched.
+        /// If the key is an arg which can have arity 1, but throws when consuming that arg, we return Error(<the message>).
+        /// This can nevertheless be a successful parse, e.g. when the key may have arity 0.
+        let processKeyValue (key : string) (value : string) : Result<unit, string option> =
+            if System.String.Equals (key, sprintf "--%s" "port", System.StringComparison.OrdinalIgnoreCase) then
+                match arg_2 with
+                | Some x ->
+                    sprintf
+                        "Argument '%s' was supplied multiple times: %s and %s"
+                        (sprintf "--%s" "port")
+                        (x.ToString ())
+                        (value.ToString ())
+                    |> ArgParser_errors.Add
+
+                    Ok ()
+                | None ->
+                    try
+                        arg_2 <- value |> (fun x -> System.Int32.Parse x) |> Some
+                        Ok ()
+                    with _ as exc ->
+                        exc.Message |> Some |> Error
+            else if System.String.Equals (key, sprintf "--%s" "verbose", System.StringComparison.OrdinalIgnoreCase) then
+                match arg_1 with
+                | Some x ->
+                    sprintf
+                        "Argument '%s' was supplied multiple times: %s and %s"
+                        (sprintf "--%s" "verbose")
+                        (x.ToString ())
+                        (value.ToString ())
+                    |> ArgParser_errors.Add
+
+                    Ok ()
+                | None ->
+                    try
+                        arg_1 <- value |> (fun x -> System.Boolean.Parse x) |> Some
+                        Ok ()
+                    with _ as exc ->
+                        exc.Message |> Some |> Error
+            else if
+                System.String.Equals (key, sprintf "--%s" "config-file", System.StringComparison.OrdinalIgnoreCase)
+            then
+                match arg_0 with
+                | Some x ->
+                    sprintf
+                        "Argument '%s' was supplied multiple times: %s and %s"
+                        (sprintf "--%s" "config-file")
+                        (x.ToString ())
+                        (value.ToString ())
+                    |> ArgParser_errors.Add
+
+                    Ok ()
+                | None ->
+                    try
+                        arg_0 <- value |> (fun x -> x) |> Some
+                        Ok ()
+                    with _ as exc ->
+                        exc.Message |> Some |> Error
+            else
+                Error None
+
+        /// Returns false if we didn't set a value.
+        let setFlagValue (key : string) : bool =
+            if System.String.Equals (key, sprintf "--%s" "verbose", System.StringComparison.OrdinalIgnoreCase) then
+                match arg_1 with
+                | Some x ->
+                    sprintf "Flag '%s' was supplied multiple times" (sprintf "--%s" "verbose")
+                    |> ArgParser_errors.Add
+
+                    true
+                | None ->
+                    arg_1 <- true |> Some
+                    true
+            else
+                false
+
+        let rec go (state : ParseState_WithTypeHelp) (args : string list) =
+            match args with
+            | [] ->
+                match state with
+                | ParseState_WithTypeHelp.AwaitingKey -> ()
+                | ParseState_WithTypeHelp.AwaitingValue key ->
+                    if setFlagValue key then
+                        ()
+                    else
+                        sprintf
+                            "Trailing argument %s had no value. Use a double-dash to separate positional args from key-value args."
+                            key
+                        |> ArgParser_errors.Add
+            | "--" :: rest -> parser_LeftoverArgs.AddRange (rest |> Seq.map (fun x -> x))
+            | arg :: args ->
+                match state with
+                | ParseState_WithTypeHelp.AwaitingKey ->
+                    if arg.StartsWith ("--", System.StringComparison.Ordinal) then
+                        if arg = "--help" then
+                            helpText () |> failwithf "Help text requested.\n%s"
+                        else
+                            let equals = arg.IndexOf (char 61)
+
+                            if equals < 0 then
+                                args |> go (ParseState_WithTypeHelp.AwaitingValue arg)
+                            else
+                                let key = arg.[0 .. equals - 1]
+                                let value = arg.[equals + 1 ..]
+
+                                match processKeyValue key value with
+                                | Ok () -> go ParseState_WithTypeHelp.AwaitingKey args
+                                | Error x ->
+                                    match x with
+                                    | None ->
+                                        failwithf "Unable to process argument %s as key %s and value %s" arg key value
+                                    | Some msg ->
+                                        sprintf "%s (at arg %s)" msg arg |> ArgParser_errors.Add
+                                        go ParseState_WithTypeHelp.AwaitingKey args
+                    else
+                        arg |> (fun x -> x) |> parser_LeftoverArgs.Add
+                        go ParseState_WithTypeHelp.AwaitingKey args
+                | ParseState_WithTypeHelp.AwaitingValue key ->
+                    match processKeyValue key arg with
+                    | Ok () -> go ParseState_WithTypeHelp.AwaitingKey args
+                    | Error exc ->
+                        if setFlagValue key then
+                            go ParseState_WithTypeHelp.AwaitingKey (arg :: args)
+                        else
+                            match exc with
+                            | None ->
+                                failwithf "Unable to process supplied arg %s. Help text follows.\n%s" key (helpText ())
+                            | Some msg -> msg |> ArgParser_errors.Add
+
+        go ParseState_WithTypeHelp.AwaitingKey args
+
+        let parser_LeftoverArgs =
+            if 0 = parser_LeftoverArgs.Count then
+                ()
+            else
+                parser_LeftoverArgs
+                |> String.concat " "
+                |> sprintf "There were leftover args: %s"
+                |> ArgParser_errors.Add
+
+                Unchecked.defaultof<_>
+
+        let arg_0 =
+            match arg_0 with
+            | None ->
+                sprintf "Required argument '%s' received no value" (sprintf "--%s" "config-file")
+                |> ArgParser_errors.Add
+
+                Unchecked.defaultof<_>
+            | Some x -> x
+
+        let arg_1 =
+            match arg_1 with
+            | None ->
+                sprintf "Required argument '%s' received no value" (sprintf "--%s" "verbose")
+                |> ArgParser_errors.Add
+
+                Unchecked.defaultof<_>
+            | Some x -> x
+
+        let arg_2 =
+            match arg_2 with
+            | None ->
+                sprintf "Required argument '%s' received no value" (sprintf "--%s" "port")
+                |> ArgParser_errors.Add
+
+                Unchecked.defaultof<_>
+            | Some x -> x
+
+        if 0 = ArgParser_errors.Count then
+            {
+                ConfigFile = arg_0
+                Port = arg_2
+                Verbose = arg_1
+            }
+        else
+            ArgParser_errors |> String.concat "\n" |> failwithf "Errors during parse!\n%s"
+
+    let parse (args : string list) : WithTypeHelp =
+        parse' (System.Environment.GetEnvironmentVariable >> Option.ofObj) args
+namespace ConsumePlugin
+
+open System
+open System.IO
+open WoofWare.Myriad.Plugins
+
+/// Methods to parse arguments for the type WithMultilineTypeHelp
+[<RequireQualifiedAccess ; CompilationRepresentation(CompilationRepresentationFlags.ModuleSuffix)>]
+module WithMultilineTypeHelp =
+    type private ParseState_WithMultilineTypeHelp =
+        /// Ready to consume a key or positional arg
+        | AwaitingKey
+        /// Waiting to receive a value for the key we've already consumed
+        | AwaitingValue of key : string
+
+    let parse' (getEnvironmentVariable : string -> string option) (args : string list) : WithMultilineTypeHelp =
+        let ArgParser_errors = ResizeArray ()
+
+        let helpText () =
+            [
+                "This is a multiline help text example.
+It spans multiple lines to test that multiline strings work correctly.
+You can use this to provide detailed documentation for your argument parser."
+
+                ""
+                (sprintf "%s  string%s%s" (sprintf "--%s" "input-file") "" (sprintf " : %s" ("Input file to process")))
+                (sprintf "%s  string%s%s" (sprintf "--%s" "output-dir") "" (sprintf " : %s" ("Output directory")))
+                (sprintf "%s  bool%s%s" (sprintf "--%s" "force") "" "")
+            ]
+            |> String.concat "\n"
+
+        let parser_LeftoverArgs : string ResizeArray = ResizeArray ()
+        let mutable arg_0 : string option = None
+        let mutable arg_1 : string option = None
+        let mutable arg_2 : bool option = None
+
+        /// Processes the key-value pair, returning Error if no key was matched.
+        /// If the key is an arg which can have arity 1, but throws when consuming that arg, we return Error(<the message>).
+        /// This can nevertheless be a successful parse, e.g. when the key may have arity 0.
+        let processKeyValue (key : string) (value : string) : Result<unit, string option> =
+            if System.String.Equals (key, sprintf "--%s" "force", System.StringComparison.OrdinalIgnoreCase) then
+                match arg_2 with
+                | Some x ->
+                    sprintf
+                        "Argument '%s' was supplied multiple times: %s and %s"
+                        (sprintf "--%s" "force")
+                        (x.ToString ())
+                        (value.ToString ())
+                    |> ArgParser_errors.Add
+
+                    Ok ()
+                | None ->
+                    try
+                        arg_2 <- value |> (fun x -> System.Boolean.Parse x) |> Some
+                        Ok ()
+                    with _ as exc ->
+                        exc.Message |> Some |> Error
+            else if
+                System.String.Equals (key, sprintf "--%s" "output-dir", System.StringComparison.OrdinalIgnoreCase)
+            then
+                match arg_1 with
+                | Some x ->
+                    sprintf
+                        "Argument '%s' was supplied multiple times: %s and %s"
+                        (sprintf "--%s" "output-dir")
+                        (x.ToString ())
+                        (value.ToString ())
+                    |> ArgParser_errors.Add
+
+                    Ok ()
+                | None ->
+                    try
+                        arg_1 <- value |> (fun x -> x) |> Some
+                        Ok ()
+                    with _ as exc ->
+                        exc.Message |> Some |> Error
+            else if
+                System.String.Equals (key, sprintf "--%s" "input-file", System.StringComparison.OrdinalIgnoreCase)
+            then
+                match arg_0 with
+                | Some x ->
+                    sprintf
+                        "Argument '%s' was supplied multiple times: %s and %s"
+                        (sprintf "--%s" "input-file")
+                        (x.ToString ())
+                        (value.ToString ())
+                    |> ArgParser_errors.Add
+
+                    Ok ()
+                | None ->
+                    try
+                        arg_0 <- value |> (fun x -> x) |> Some
+                        Ok ()
+                    with _ as exc ->
+                        exc.Message |> Some |> Error
+            else
+                Error None
+
+        /// Returns false if we didn't set a value.
+        let setFlagValue (key : string) : bool =
+            if System.String.Equals (key, sprintf "--%s" "force", System.StringComparison.OrdinalIgnoreCase) then
+                match arg_2 with
+                | Some x ->
+                    sprintf "Flag '%s' was supplied multiple times" (sprintf "--%s" "force")
+                    |> ArgParser_errors.Add
+
+                    true
+                | None ->
+                    arg_2 <- true |> Some
+                    true
+            else
+                false
+
+        let rec go (state : ParseState_WithMultilineTypeHelp) (args : string list) =
+            match args with
+            | [] ->
+                match state with
+                | ParseState_WithMultilineTypeHelp.AwaitingKey -> ()
+                | ParseState_WithMultilineTypeHelp.AwaitingValue key ->
+                    if setFlagValue key then
+                        ()
+                    else
+                        sprintf
+                            "Trailing argument %s had no value. Use a double-dash to separate positional args from key-value args."
+                            key
+                        |> ArgParser_errors.Add
+            | "--" :: rest -> parser_LeftoverArgs.AddRange (rest |> Seq.map (fun x -> x))
+            | arg :: args ->
+                match state with
+                | ParseState_WithMultilineTypeHelp.AwaitingKey ->
+                    if arg.StartsWith ("--", System.StringComparison.Ordinal) then
+                        if arg = "--help" then
+                            helpText () |> failwithf "Help text requested.\n%s"
+                        else
+                            let equals = arg.IndexOf (char 61)
+
+                            if equals < 0 then
+                                args |> go (ParseState_WithMultilineTypeHelp.AwaitingValue arg)
+                            else
+                                let key = arg.[0 .. equals - 1]
+                                let value = arg.[equals + 1 ..]
+
+                                match processKeyValue key value with
+                                | Ok () -> go ParseState_WithMultilineTypeHelp.AwaitingKey args
+                                | Error x ->
+                                    match x with
+                                    | None ->
+                                        failwithf "Unable to process argument %s as key %s and value %s" arg key value
+                                    | Some msg ->
+                                        sprintf "%s (at arg %s)" msg arg |> ArgParser_errors.Add
+                                        go ParseState_WithMultilineTypeHelp.AwaitingKey args
+                    else
+                        arg |> (fun x -> x) |> parser_LeftoverArgs.Add
+                        go ParseState_WithMultilineTypeHelp.AwaitingKey args
+                | ParseState_WithMultilineTypeHelp.AwaitingValue key ->
+                    match processKeyValue key arg with
+                    | Ok () -> go ParseState_WithMultilineTypeHelp.AwaitingKey args
+                    | Error exc ->
+                        if setFlagValue key then
+                            go ParseState_WithMultilineTypeHelp.AwaitingKey (arg :: args)
+                        else
+                            match exc with
+                            | None ->
+                                failwithf "Unable to process supplied arg %s. Help text follows.\n%s" key (helpText ())
+                            | Some msg -> msg |> ArgParser_errors.Add
+
+        go ParseState_WithMultilineTypeHelp.AwaitingKey args
+
+        let parser_LeftoverArgs =
+            if 0 = parser_LeftoverArgs.Count then
+                ()
+            else
+                parser_LeftoverArgs
+                |> String.concat " "
+                |> sprintf "There were leftover args: %s"
+                |> ArgParser_errors.Add
+
+                Unchecked.defaultof<_>
+
+        let arg_0 =
+            match arg_0 with
+            | None ->
+                sprintf "Required argument '%s' received no value" (sprintf "--%s" "input-file")
+                |> ArgParser_errors.Add
+
+                Unchecked.defaultof<_>
+            | Some x -> x
+
+        let arg_1 =
+            match arg_1 with
+            | None ->
+                sprintf "Required argument '%s' received no value" (sprintf "--%s" "output-dir")
+                |> ArgParser_errors.Add
+
+                Unchecked.defaultof<_>
+            | Some x -> x
+
+        let arg_2 =
+            match arg_2 with
+            | None ->
+                sprintf "Required argument '%s' received no value" (sprintf "--%s" "force")
+                |> ArgParser_errors.Add
+
+                Unchecked.defaultof<_>
+            | Some x -> x
+
+        if 0 = ArgParser_errors.Count then
+            {
+                Force = arg_2
+                InputFile = arg_0
+                OutputDir = arg_1
+            }
+        else
+            ArgParser_errors |> String.concat "\n" |> failwithf "Errors during parse!\n%s"
+
+    let parse (args : string list) : WithMultilineTypeHelp =
+        parse' (System.Environment.GetEnvironmentVariable >> Option.ofObj) args

ConsumePlugin/GeneratedCapturingMock.fs

@@ -36,7 +36,7 @@ type internal PublicTypeMock =
         Mem3 : int * System.Threading.CancellationToken option -> string
     }
 
-    /// An implementation where every non-unit method throws.
+    /// An implementation where every non-disposal method throws.
     static member Empty () : PublicTypeMock =
         {
             Calls = PublicTypeMockCalls.Calls.Empty ()
@@ -89,7 +89,7 @@ type public PublicTypeInternalFalseMock =
         Mem3 : int * System.Threading.CancellationToken option -> string
     }
 
-    /// An implementation where every non-unit method throws.
+    /// An implementation where every non-disposal method throws.
     static member Empty () : PublicTypeInternalFalseMock =
         {
             Calls = PublicTypeInternalFalseMockCalls.Calls.Empty ()
@@ -139,7 +139,7 @@ type internal InternalTypeMock =
         Mem2 : string -> int
     }
 
-    /// An implementation where every non-unit method throws.
+    /// An implementation where every non-disposal method throws.
     static member Empty () : InternalTypeMock =
         {
             Calls = InternalTypeMockCalls.Calls.Empty ()
@@ -184,7 +184,7 @@ type private PrivateTypeMock =
         Mem2 : string -> int
     }
 
-    /// An implementation where every non-unit method throws.
+    /// An implementation where every non-disposal method throws.
     static member Empty () : PrivateTypeMock =
         {
             Calls = PrivateTypeMockCalls.Calls.Empty ()
@@ -229,7 +229,7 @@ type private PrivateTypeInternalFalseMock =
         Mem2 : string -> int
     }
 
-    /// An implementation where every non-unit method throws.
+    /// An implementation where every non-disposal method throws.
     static member Empty () : PrivateTypeInternalFalseMock =
         {
             Calls = PrivateTypeInternalFalseMockCalls.Calls.Empty ()
@@ -271,7 +271,7 @@ type internal VeryPublicTypeMock<'a, 'b> =
         Mem1 : 'a -> 'b
     }
 
-    /// An implementation where every non-unit method throws.
+    /// An implementation where every non-disposal method throws.
     static member Empty () : VeryPublicTypeMock<'a, 'b> =
         {
             Calls = VeryPublicTypeMockCalls.Calls.Empty ()
@@ -365,7 +365,7 @@ type internal CurriedMock<'a> =
         Mem6 : int * string -> 'a * int -> string
     }
 
-    /// An implementation where every non-unit method throws.
+    /// An implementation where every non-disposal method throws.
     static member Empty () : CurriedMock<'a> =
         {
             Calls = CurriedMockCalls.Calls.Empty ()
@@ -486,7 +486,7 @@ type internal TypeWithInterfaceMock =
         Mem2 : unit -> string[] Async
     }
 
-    /// An implementation where every non-unit method throws.
+    /// An implementation where every non-disposal method throws.
     static member Empty () : TypeWithInterfaceMock =
         {
             Calls = TypeWithInterfaceMockCalls.Calls.Empty ()
@@ -540,7 +540,7 @@ type internal TypeWithPropertiesMock =
         Prop2 : unit -> unit Async
     }
 
-    /// An implementation where every non-unit method throws.
+    /// An implementation where every non-disposal method throws.
     static member Empty () : TypeWithPropertiesMock =
         {
             Calls = TypeWithPropertiesMockCalls.Calls.Empty ()
@@ -560,3 +560,103 @@ type internal TypeWithPropertiesMock =
 
     interface System.IDisposable with
         member this.Dispose () : unit = this.Dispose ()
+namespace SomeNamespace.CapturingMock
+
+open System
+open WoofWare.Myriad.Plugins
+
+[<RequireQualifiedAccess>]
+module internal TypeWithAsyncDisposableMockCalls =
+    /// All the calls made to a TypeWithAsyncDisposableMock mock
+    type internal Calls =
+        {
+            Mem1 : ResizeArray<string option>
+            Mem2 : ResizeArray<unit>
+        }
+
+        /// A fresh calls object which has not yet had any calls made.
+        static member Empty () : Calls =
+            {
+                Mem1 = ResizeArray ()
+                Mem2 = ResizeArray ()
+            }
+
+/// Mock record type for an interface
+type internal TypeWithAsyncDisposableMock =
+    {
+        Calls : TypeWithAsyncDisposableMockCalls.Calls
+        /// Implementation of IAsyncDisposable.DisposeAsync
+        DisposeAsync : unit -> System.Threading.Tasks.ValueTask
+        Mem1 : string option -> string[] Async
+        Mem2 : unit -> string[] Async
+    }
+
+    /// An implementation where every non-disposal method throws.
+    static member Empty () : TypeWithAsyncDisposableMock =
+        {
+            Calls = TypeWithAsyncDisposableMockCalls.Calls.Empty ()
+            DisposeAsync = (fun () -> (System.Threading.Tasks.ValueTask ()))
+            Mem1 = (fun _ -> raise (System.NotImplementedException "Unimplemented mock function: Mem1"))
+            Mem2 = (fun _ -> raise (System.NotImplementedException "Unimplemented mock function: Mem2"))
+        }
+
+    interface TypeWithAsyncDisposable with
+        member this.Mem1 arg_0_0 =
+            lock this.Calls.Mem1 (fun _ -> this.Calls.Mem1.Add (arg_0_0))
+            this.Mem1 (arg_0_0)
+
+        member this.Mem2 () =
+            lock this.Calls.Mem2 (fun _ -> this.Calls.Mem2.Add (()))
+            this.Mem2 (())
+
+    interface System.IAsyncDisposable with
+        member this.DisposeAsync () : System.Threading.Tasks.ValueTask = this.DisposeAsync ()
+namespace SomeNamespace.CapturingMock
+
+open System
+open WoofWare.Myriad.Plugins
+
+[<RequireQualifiedAccess>]
+module internal TypeWithBothDisposablesMockCalls =
+    /// All the calls made to a TypeWithBothDisposablesMock mock
+    type internal Calls =
+        {
+            Mem1 : ResizeArray<string>
+        }
+
+        /// A fresh calls object which has not yet had any calls made.
+        static member Empty () : Calls =
+            {
+                Mem1 = ResizeArray ()
+            }
+
+/// Mock record type for an interface
+type internal TypeWithBothDisposablesMock =
+    {
+        Calls : TypeWithBothDisposablesMockCalls.Calls
+        /// Implementation of IDisposable.Dispose
+        Dispose : unit -> unit
+        /// Implementation of IAsyncDisposable.DisposeAsync
+        DisposeAsync : unit -> System.Threading.Tasks.ValueTask
+        Mem1 : string -> int
+    }
+
+    /// An implementation where every non-disposal method throws.
+    static member Empty () : TypeWithBothDisposablesMock =
+        {
+            Calls = TypeWithBothDisposablesMockCalls.Calls.Empty ()
+            Dispose = (fun () -> ())
+            DisposeAsync = (fun () -> (System.Threading.Tasks.ValueTask ()))
+            Mem1 = (fun _ -> raise (System.NotImplementedException "Unimplemented mock function: Mem1"))
+        }
+
+    interface TypeWithBothDisposables with
+        member this.Mem1 arg_0_0 =
+            lock this.Calls.Mem1 (fun _ -> this.Calls.Mem1.Add (arg_0_0))
+            this.Mem1 (arg_0_0)
+
+    interface System.IDisposable with
+        member this.Dispose () : unit = this.Dispose ()
+
+    interface System.IAsyncDisposable with
+        member this.DisposeAsync () : System.Threading.Tasks.ValueTask = this.DisposeAsync ()

ConsumePlugin/GeneratedCapturingMockNoAttributes.fs

@@ -35,7 +35,7 @@ type internal PublicTypeNoAttrMock =
         Mem3 : int * System.Threading.CancellationToken option -> string
     }
 
-    /// An implementation where every non-unit method throws.
+    /// An implementation where every non-disposal method throws.
     static member Empty () : PublicTypeNoAttrMock =
         {
             Calls = PublicTypeNoAttrMockCalls.Calls.Empty ()
@@ -87,7 +87,7 @@ type public PublicTypeInternalFalseNoAttrMock =
         Mem3 : int * System.Threading.CancellationToken option -> string
     }
 
-    /// An implementation where every non-unit method throws.
+    /// An implementation where every non-disposal method throws.
     static member Empty () : PublicTypeInternalFalseNoAttrMock =
         {
             Calls = PublicTypeInternalFalseNoAttrMockCalls.Calls.Empty ()
@@ -136,7 +136,7 @@ type internal InternalTypeNoAttrMock =
         Mem2 : string -> int
     }
 
-    /// An implementation where every non-unit method throws.
+    /// An implementation where every non-disposal method throws.
     static member Empty () : InternalTypeNoAttrMock =
         {
             Calls = InternalTypeNoAttrMockCalls.Calls.Empty ()
@@ -180,7 +180,7 @@ type private PrivateTypeNoAttrMock =
         Mem2 : string -> int
     }
 
-    /// An implementation where every non-unit method throws.
+    /// An implementation where every non-disposal method throws.
     static member Empty () : PrivateTypeNoAttrMock =
         {
             Calls = PrivateTypeNoAttrMockCalls.Calls.Empty ()
@@ -224,7 +224,7 @@ type private PrivateTypeInternalFalseNoAttrMock =
         Mem2 : string -> int
     }
 
-    /// An implementation where every non-unit method throws.
+    /// An implementation where every non-disposal method throws.
     static member Empty () : PrivateTypeInternalFalseNoAttrMock =
         {
             Calls = PrivateTypeInternalFalseNoAttrMockCalls.Calls.Empty ()
@@ -265,7 +265,7 @@ type internal VeryPublicTypeNoAttrMock<'a, 'b> =
         Mem1 : 'a -> 'b
     }
 
-    /// An implementation where every non-unit method throws.
+    /// An implementation where every non-disposal method throws.
     static member Empty () : VeryPublicTypeNoAttrMock<'a, 'b> =
         {
             Calls = VeryPublicTypeNoAttrMockCalls.Calls.Empty ()
@@ -358,7 +358,7 @@ type internal CurriedNoAttrMock<'a> =
         Mem6 : int * string -> 'a * int -> string
     }
 
-    /// An implementation where every non-unit method throws.
+    /// An implementation where every non-disposal method throws.
     static member Empty () : CurriedNoAttrMock<'a> =
         {
             Calls = CurriedNoAttrMockCalls.Calls.Empty ()
@@ -478,7 +478,7 @@ type internal TypeWithInterfaceNoAttrMock =
         Mem2 : unit -> string[] Async
     }
 
-    /// An implementation where every non-unit method throws.
+    /// An implementation where every non-disposal method throws.
     static member Empty () : TypeWithInterfaceNoAttrMock =
         {
             Calls = TypeWithInterfaceNoAttrMockCalls.Calls.Empty ()

ConsumePlugin/GeneratedCatamorphismNoAttribute.fs

@@ -0,0 +1,144 @@
+//------------------------------------------------------------------------------
+//        This code was generated by myriad.
+//        Changes to this file will be lost when the code is regenerated.
+//------------------------------------------------------------------------------
+
+
+
+
+
+
+namespace ConsumePluginNoAttr
+
+/// Description of how to combine cases during a fold
+type TreeBuilderNoAttrCataCase<'b, 'a, 'TreeBuilderNoAttr, 'TreeNoAttr> =
+    /// How to operate on the Child case
+    abstract Child : 'TreeBuilderNoAttr -> 'TreeBuilderNoAttr
+    /// How to operate on the Parent case
+    abstract Parent : 'TreeNoAttr -> 'TreeBuilderNoAttr
+
+/// Description of how to combine cases during a fold
+type TreeNoAttrCataCase<'a, 'b, 'TreeBuilderNoAttr, 'TreeNoAttr> =
+    /// How to operate on the Const case
+    abstract Const : ConstNoAttr<'a> -> 'b -> 'TreeNoAttr
+    /// How to operate on the Pair case
+    abstract Pair : 'TreeNoAttr -> 'TreeNoAttr -> PairOpKindNoAttr -> 'TreeNoAttr
+    /// How to operate on the Sequential case
+    abstract Sequential : 'TreeNoAttr list -> 'TreeNoAttr
+    /// How to operate on the Builder case
+    abstract Builder : 'TreeNoAttr -> 'TreeBuilderNoAttr -> 'TreeNoAttr
+
+/// Specifies how to perform a fold (catamorphism) over the type TreeNoAttr and its friends.
+type TreeNoAttrCata<'b, 'a, 'TreeBuilderNoAttr, 'TreeNoAttr> =
+    {
+        /// How to perform a fold (catamorphism) over the type TreeBuilderNoAttr
+        TreeBuilderNoAttr : TreeBuilderNoAttrCataCase<'b, 'a, 'TreeBuilderNoAttr, 'TreeNoAttr>
+        /// How to perform a fold (catamorphism) over the type TreeNoAttr
+        TreeNoAttr : TreeNoAttrCataCase<'a, 'b, 'TreeBuilderNoAttr, 'TreeNoAttr>
+    }
+
+/// Methods to perform a catamorphism over the type TreeNoAttr
+[<RequireQualifiedAccess>]
+module TreeNoAttrCata =
+    [<RequireQualifiedAccess>]
+    type private Instruction<'b, 'a> =
+        | Process__TreeBuilderNoAttr of TreeBuilderNoAttr<'b, 'a>
+        | Process__TreeNoAttr of TreeNoAttr<'a, 'b>
+        | TreeBuilderNoAttr_Child
+        | TreeBuilderNoAttr_Parent
+        | TreeNoAttr_Pair of PairOpKindNoAttr
+        | TreeNoAttr_Sequential of int
+        | TreeNoAttr_Builder
+
+    let private loop
+        (cata : TreeNoAttrCata<'b, 'a, 'TreeBuilderNoAttr, 'TreeNoAttr>)
+        (instructions : ResizeArray<Instruction<'b, 'a>>)
+        =
+        let treeNoAttrStack = ResizeArray<'TreeNoAttr> ()
+        let treeBuilderNoAttrStack = ResizeArray<'TreeBuilderNoAttr> ()
+
+        while instructions.Count > 0 do
+            let currentInstruction = instructions.[instructions.Count - 1]
+            instructions.RemoveAt (instructions.Count - 1)
+
+            match currentInstruction with
+            | Instruction.Process__TreeBuilderNoAttr x ->
+                match x with
+                | TreeBuilderNoAttr.Child (arg0_0) ->
+                    instructions.Add Instruction.TreeBuilderNoAttr_Child
+                    instructions.Add (Instruction.Process__TreeBuilderNoAttr arg0_0)
+                | TreeBuilderNoAttr.Parent (arg0_0) ->
+                    instructions.Add Instruction.TreeBuilderNoAttr_Parent
+                    instructions.Add (Instruction.Process__TreeNoAttr arg0_0)
+            | Instruction.Process__TreeNoAttr x ->
+                match x with
+                | TreeNoAttr.Const (arg0_0, arg1_0) -> cata.TreeNoAttr.Const arg0_0 arg1_0 |> treeNoAttrStack.Add
+                | TreeNoAttr.Pair (arg0_0, arg1_0, arg2_0) ->
+                    instructions.Add (Instruction.TreeNoAttr_Pair (arg2_0))
+                    instructions.Add (Instruction.Process__TreeNoAttr arg0_0)
+                    instructions.Add (Instruction.Process__TreeNoAttr arg1_0)
+                | TreeNoAttr.Sequential (arg0_0) ->
+                    instructions.Add (Instruction.TreeNoAttr_Sequential ((List.length arg0_0)))
+
+                    for elt in arg0_0 do
+                        instructions.Add (Instruction.Process__TreeNoAttr elt)
+                | TreeNoAttr.Builder (arg0_0, arg1_0) ->
+                    instructions.Add Instruction.TreeNoAttr_Builder
+                    instructions.Add (Instruction.Process__TreeNoAttr arg0_0)
+                    instructions.Add (Instruction.Process__TreeBuilderNoAttr arg1_0)
+            | Instruction.TreeBuilderNoAttr_Child ->
+                let arg0_0 = treeBuilderNoAttrStack.[treeBuilderNoAttrStack.Count - 1]
+                treeBuilderNoAttrStack.RemoveAt (treeBuilderNoAttrStack.Count - 1)
+                cata.TreeBuilderNoAttr.Child arg0_0 |> treeBuilderNoAttrStack.Add
+            | Instruction.TreeBuilderNoAttr_Parent ->
+                let arg0_0 = treeNoAttrStack.[treeNoAttrStack.Count - 1]
+                treeNoAttrStack.RemoveAt (treeNoAttrStack.Count - 1)
+                cata.TreeBuilderNoAttr.Parent arg0_0 |> treeBuilderNoAttrStack.Add
+            | Instruction.TreeNoAttr_Pair arg2_0 ->
+                let arg0_0 = treeNoAttrStack.[treeNoAttrStack.Count - 1]
+                treeNoAttrStack.RemoveAt (treeNoAttrStack.Count - 1)
+                let arg1_0 = treeNoAttrStack.[treeNoAttrStack.Count - 1]
+                treeNoAttrStack.RemoveAt (treeNoAttrStack.Count - 1)
+                cata.TreeNoAttr.Pair arg0_0 arg1_0 arg2_0 |> treeNoAttrStack.Add
+            | Instruction.TreeNoAttr_Sequential arg0_0 ->
+                let arg0_0_len = arg0_0
+
+                let arg0_0 =
+                    seq {
+                        for i = treeNoAttrStack.Count - 1 downto treeNoAttrStack.Count - arg0_0 do
+                            yield treeNoAttrStack.[i]
+                    }
+                    |> Seq.toList
+
+                treeNoAttrStack.RemoveRange (treeNoAttrStack.Count - arg0_0_len, arg0_0_len)
+                cata.TreeNoAttr.Sequential arg0_0 |> treeNoAttrStack.Add
+            | Instruction.TreeNoAttr_Builder ->
+                let arg0_0 = treeNoAttrStack.[treeNoAttrStack.Count - 1]
+                treeNoAttrStack.RemoveAt (treeNoAttrStack.Count - 1)
+                let arg1_0 = treeBuilderNoAttrStack.[treeBuilderNoAttrStack.Count - 1]
+                treeBuilderNoAttrStack.RemoveAt (treeBuilderNoAttrStack.Count - 1)
+                cata.TreeNoAttr.Builder arg0_0 arg1_0 |> treeNoAttrStack.Add
+
+        treeBuilderNoAttrStack, treeNoAttrStack
+
+    /// Execute the catamorphism.
+    let runTreeBuilderNoAttr
+        (cata : TreeNoAttrCata<'b, 'a, 'TreeBuilderNoAttrRet, 'TreeNoAttrRet>)
+        (x : TreeBuilderNoAttr<'b, 'a>)
+        : 'TreeBuilderNoAttrRet
+        =
+        let instructions = ResizeArray ()
+        instructions.Add (Instruction.Process__TreeBuilderNoAttr x)
+        let treeBuilderNoAttrRetStack, treeNoAttrRetStack = loop cata instructions
+        Seq.exactlyOne treeBuilderNoAttrRetStack
+
+    /// Execute the catamorphism.
+    let runTreeNoAttr
+        (cata : TreeNoAttrCata<'b, 'a, 'TreeBuilderNoAttrRet, 'TreeNoAttrRet>)
+        (x : TreeNoAttr<'a, 'b>)
+        : 'TreeNoAttrRet
+        =
+        let instructions = ResizeArray ()
+        instructions.Add (Instruction.Process__TreeNoAttr x)
+        let treeBuilderNoAttrRetStack, treeNoAttrRetStack = loop cata instructions
+        Seq.exactlyOne treeNoAttrRetStack

ConsumePlugin/GeneratedMock.fs

@@ -16,7 +16,7 @@ type internal PublicTypeMock =
         Mem3 : int * option<System.Threading.CancellationToken> -> string
     }
 
-    /// An implementation where every method throws.
+    /// An implementation where every non-disposal method throws.
     static member Empty : PublicTypeMock =
         {
             Mem1 = (fun _ -> raise (System.NotImplementedException "Unimplemented mock function: Mem1"))
@@ -41,7 +41,7 @@ type public PublicTypeInternalFalseMock =
         Mem3 : int * option<System.Threading.CancellationToken> -> string
     }
 
-    /// An implementation where every method throws.
+    /// An implementation where every non-disposal method throws.
     static member Empty : PublicTypeInternalFalseMock =
         {
             Mem1 = (fun _ -> raise (System.NotImplementedException "Unimplemented mock function: Mem1"))
@@ -65,7 +65,7 @@ type internal InternalTypeMock =
         Mem2 : string -> int
     }
 
-    /// An implementation where every method throws.
+    /// An implementation where every non-disposal method throws.
     static member Empty : InternalTypeMock =
         {
             Mem1 = (fun _ -> raise (System.NotImplementedException "Unimplemented mock function: Mem1"))
@@ -87,7 +87,7 @@ type private PrivateTypeMock =
         Mem2 : string -> int
     }
 
-    /// An implementation where every method throws.
+    /// An implementation where every non-disposal method throws.
     static member Empty : PrivateTypeMock =
         {
             Mem1 = (fun _ -> raise (System.NotImplementedException "Unimplemented mock function: Mem1"))
@@ -109,7 +109,7 @@ type private PrivateTypeInternalFalseMock =
         Mem2 : string -> int
     }
 
-    /// An implementation where every method throws.
+    /// An implementation where every non-disposal method throws.
     static member Empty : PrivateTypeInternalFalseMock =
         {
             Mem1 = (fun _ -> raise (System.NotImplementedException "Unimplemented mock function: Mem1"))
@@ -130,7 +130,7 @@ type internal VeryPublicTypeMock<'a, 'b> =
         Mem1 : 'a -> 'b
     }
 
-    /// An implementation where every method throws.
+    /// An implementation where every non-disposal method throws.
     static member Empty () : VeryPublicTypeMock<'a, 'b> =
         {
             Mem1 = (fun _ -> raise (System.NotImplementedException "Unimplemented mock function: Mem1"))
@@ -154,7 +154,7 @@ type internal CurriedMock<'a> =
         Mem6 : int * string -> 'a * int -> string
     }
 
-    /// An implementation where every method throws.
+    /// An implementation where every non-disposal method throws.
     static member Empty () : CurriedMock<'a> =
         {
             Mem1 = (fun _ -> raise (System.NotImplementedException "Unimplemented mock function: Mem1"))
@@ -192,7 +192,7 @@ type internal TypeWithInterfaceMock =
         Mem2 : unit -> string[] Async
     }
 
-    /// An implementation where every method throws.
+    /// An implementation where every non-disposal method throws.
     static member Empty : TypeWithInterfaceMock =
         {
             Dispose = (fun () -> ())
@@ -221,7 +221,7 @@ type internal TypeWithPropertiesMock =
         Mem1 : string option -> string[] Async
     }
 
-    /// An implementation where every method throws.
+    /// An implementation where every non-disposal method throws.
     static member Empty : TypeWithPropertiesMock =
         {
             Dispose = (fun () -> ())
@@ -237,3 +237,62 @@ type internal TypeWithPropertiesMock =
 
     interface System.IDisposable with
         member this.Dispose () : unit = this.Dispose ()
+namespace SomeNamespace
+
+open System
+open WoofWare.Myriad.Plugins
+
+/// Mock record type for an interface
+type internal TypeWithAsyncDisposableMock =
+    {
+        /// Implementation of IAsyncDisposable.DisposeAsync
+        DisposeAsync : unit -> System.Threading.Tasks.ValueTask
+        Mem1 : string option -> string[] Async
+        Mem2 : unit -> string[] Async
+    }
+
+    /// An implementation where every non-disposal method throws.
+    static member Empty : TypeWithAsyncDisposableMock =
+        {
+            DisposeAsync = (fun () -> (System.Threading.Tasks.ValueTask ()))
+            Mem1 = (fun _ -> raise (System.NotImplementedException "Unimplemented mock function: Mem1"))
+            Mem2 = (fun _ -> raise (System.NotImplementedException "Unimplemented mock function: Mem2"))
+        }
+
+    interface TypeWithAsyncDisposable with
+        member this.Mem1 arg_0_0 = this.Mem1 (arg_0_0)
+        member this.Mem2 () = this.Mem2 (())
+
+    interface System.IAsyncDisposable with
+        member this.DisposeAsync () : System.Threading.Tasks.ValueTask = this.DisposeAsync ()
+namespace SomeNamespace
+
+open System
+open WoofWare.Myriad.Plugins
+
+/// Mock record type for an interface
+type internal TypeWithBothDisposablesMock =
+    {
+        /// Implementation of IDisposable.Dispose
+        Dispose : unit -> unit
+        /// Implementation of IAsyncDisposable.DisposeAsync
+        DisposeAsync : unit -> System.Threading.Tasks.ValueTask
+        Mem1 : string -> int
+    }
+
+    /// An implementation where every non-disposal method throws.
+    static member Empty : TypeWithBothDisposablesMock =
+        {
+            Dispose = (fun () -> ())
+            DisposeAsync = (fun () -> (System.Threading.Tasks.ValueTask ()))
+            Mem1 = (fun _ -> raise (System.NotImplementedException "Unimplemented mock function: Mem1"))
+        }
+
+    interface TypeWithBothDisposables with
+        member this.Mem1 arg_0_0 = this.Mem1 (arg_0_0)
+
+    interface System.IDisposable with
+        member this.Dispose () : unit = this.Dispose ()
+
+    interface System.IAsyncDisposable with
+        member this.DisposeAsync () : System.Threading.Tasks.ValueTask = this.DisposeAsync ()

ConsumePlugin/GeneratedMockNoAttributes.fs

@@ -15,7 +15,7 @@ type internal PublicTypeNoAttrMock =
         Mem3 : int * option<System.Threading.CancellationToken> -> string
     }
 
-    /// An implementation where every method throws.
+    /// An implementation where every non-disposal method throws.
     static member Empty : PublicTypeNoAttrMock =
         {
             Mem1 = (fun _ -> raise (System.NotImplementedException "Unimplemented mock function: Mem1"))
@@ -39,7 +39,7 @@ type public PublicTypeInternalFalseNoAttrMock =
         Mem3 : int * option<System.Threading.CancellationToken> -> string
     }
 
-    /// An implementation where every method throws.
+    /// An implementation where every non-disposal method throws.
     static member Empty : PublicTypeInternalFalseNoAttrMock =
         {
             Mem1 = (fun _ -> raise (System.NotImplementedException "Unimplemented mock function: Mem1"))
@@ -62,7 +62,7 @@ type internal InternalTypeNoAttrMock =
         Mem2 : string -> int
     }
 
-    /// An implementation where every method throws.
+    /// An implementation where every non-disposal method throws.
     static member Empty : InternalTypeNoAttrMock =
         {
             Mem1 = (fun _ -> raise (System.NotImplementedException "Unimplemented mock function: Mem1"))
@@ -83,7 +83,7 @@ type private PrivateTypeNoAttrMock =
         Mem2 : string -> int
     }
 
-    /// An implementation where every method throws.
+    /// An implementation where every non-disposal method throws.
     static member Empty : PrivateTypeNoAttrMock =
         {
             Mem1 = (fun _ -> raise (System.NotImplementedException "Unimplemented mock function: Mem1"))
@@ -104,7 +104,7 @@ type private PrivateTypeInternalFalseNoAttrMock =
         Mem2 : string -> int
     }
 
-    /// An implementation where every method throws.
+    /// An implementation where every non-disposal method throws.
     static member Empty : PrivateTypeInternalFalseNoAttrMock =
         {
             Mem1 = (fun _ -> raise (System.NotImplementedException "Unimplemented mock function: Mem1"))
@@ -124,7 +124,7 @@ type internal VeryPublicTypeNoAttrMock<'a, 'b> =
         Mem1 : 'a -> 'b
     }
 
-    /// An implementation where every method throws.
+    /// An implementation where every non-disposal method throws.
     static member Empty () : VeryPublicTypeNoAttrMock<'a, 'b> =
         {
             Mem1 = (fun _ -> raise (System.NotImplementedException "Unimplemented mock function: Mem1"))
@@ -147,7 +147,7 @@ type internal CurriedNoAttrMock<'a> =
         Mem6 : int * string -> 'a * int -> string
     }
 
-    /// An implementation where every method throws.
+    /// An implementation where every non-disposal method throws.
     static member Empty () : CurriedNoAttrMock<'a> =
         {
             Mem1 = (fun _ -> raise (System.NotImplementedException "Unimplemented mock function: Mem1"))
@@ -184,7 +184,7 @@ type internal TypeWithInterfaceNoAttrMock =
         Mem2 : unit -> string[] Async
     }
 
-    /// An implementation where every method throws.
+    /// An implementation where every non-disposal method throws.
     static member Empty : TypeWithInterfaceNoAttrMock =
         {
             Dispose = (fun () -> ())

ConsumePlugin/MockExample.fs

@@ -55,3 +55,15 @@ type TypeWithProperties =
     abstract Mem1 : string option -> string[] Async
     abstract Prop1 : int
     abstract Prop2 : unit Async
+
+[<GenerateMock>]
+type TypeWithAsyncDisposable =
+    inherit IAsyncDisposable
+    abstract Mem1 : string option -> string[] Async
+    abstract Mem2 : unit -> string[] Async
+
+[<GenerateMock>]
+type TypeWithBothDisposables =
+    inherit IDisposable
+    inherit IAsyncDisposable
+    abstract Mem1 : string -> int

WoofWare.Myriad.Plugins.Attributes/ArgParserAttributes.fs

@@ -62,8 +62,10 @@ type ArgumentDefaultFunctionAttribute () =
 type ArgumentDefaultEnvironmentVariableAttribute (envVar : string) =
     inherit Attribute ()
 
-/// Attribute indicating that this field shall have the given help text, when `--help` is invoked
+/// Attribute indicating that this field or type shall have the given help text, when `--help` is invoked
 /// or when a parse error causes us to print help text.
+/// When applied to a record type, the help text appears at the top of the help output, before the field descriptions.
+/// When applied to a field, the help text appears next to that field's description.
 type ArgumentHelpTextAttribute (helpText : string) =
     inherit Attribute ()
 
@@ -100,3 +102,24 @@ type ArgumentFlagAttribute (flagValue : bool) =
 [<AttributeUsage(AttributeTargets.Field, AllowMultiple = true)>]
 type ArgumentLongForm (s : string) =
     inherit Attribute ()
+
+/// Attribute indicating that this boolean or flag field should accept `--no-` prefix for negation.
+/// When this attribute is present on a boolean or flag DU field, the generated parser will accept
+/// both --field-name and --no-field-name as argument forms.
+///
+/// For boolean fields:
+///   --field-name (or --field-name=true) sets the value to true
+///   --no-field-name (or --no-field-name=true) sets the value to false
+///   --field-name=false sets the value to false
+///   --no-field-name=false sets the value to true
+///
+/// For flag DU fields with [<ArgumentFlag>]:
+///   --field-name (or --field-name=true) sets to the case marked with [<ArgumentFlag true>]
+///   --no-field-name (or --no-field-name=true) sets to the case marked with [<ArgumentFlag false>]
+///   --field-name=false sets to the [<ArgumentFlag false>] case
+///   --no-field-name=false sets to the [<ArgumentFlag true>] case
+///
+/// This attribute can only be applied to bool fields or flag DU fields (two-case DUs with [<ArgumentFlag>]).
+[<AttributeUsage(AttributeTargets.Field, AllowMultiple = false)>]
+type ArgumentNegateWithPrefixAttribute () =
+    inherit Attribute ()

WoofWare.Myriad.Plugins.Attributes/SurfaceBaseline.txt

@@ -13,6 +13,8 @@ WoofWare.Myriad.Plugins.ArgumentHelpTextAttribute inherit System.Attribute
 WoofWare.Myriad.Plugins.ArgumentHelpTextAttribute..ctor [constructor]: string
 WoofWare.Myriad.Plugins.ArgumentLongForm inherit System.Attribute
 WoofWare.Myriad.Plugins.ArgumentLongForm..ctor [constructor]: string
+WoofWare.Myriad.Plugins.ArgumentNegateWithPrefixAttribute inherit System.Attribute
+WoofWare.Myriad.Plugins.ArgumentNegateWithPrefixAttribute..ctor [constructor]: unit
 WoofWare.Myriad.Plugins.CreateCatamorphismAttribute inherit System.Attribute
 WoofWare.Myriad.Plugins.CreateCatamorphismAttribute..ctor [constructor]: string
 WoofWare.Myriad.Plugins.GenerateCapturingMockAttribute inherit System.Attribute

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

@@ -17,8 +17,8 @@
     </ItemGroup>
 
     <ItemGroup>
-        <PackageReference Include="ApiSurface" Version="5.0.2" />
+        <PackageReference Include="ApiSurface" Version="5.0.3" />
-        <PackageReference Include="Microsoft.NET.Test.Sdk" Version="18.0.0"/>
+        <PackageReference Include="Microsoft.NET.Test.Sdk" Version="18.0.1"/>
         <PackageReference Include="NUnit" Version="4.3.2"/>
         <PackageReference Include="NUnit3TestAdapter" Version="5.2.0"/>
     </ItemGroup>

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

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
     <TargetFramework>netstandard2.0</TargetFramework>

WoofWare.Myriad.Plugins.Attributes/version.json

@@ -1,5 +1,5 @@
 {
-  "version": "3.7",
+  "version": "3.8",
   "publicReleaseRefSpec": [
     "^refs/heads/main$"
   ],

WoofWare.Myriad.Plugins.Test/TestArgParser/TestArgParser.fs

@@ -444,7 +444,7 @@ Required argument '--exact' received no value"""
         ]
         |> List.map TestCaseData
 
-    [<TestCaseSource(nameof (boolCases))>]
+    [<TestCaseSource(nameof boolCases)>]
     let ``Bool env vars can be populated`` (envValue : string, boolValue : bool) =
         let getEnvVar (s : string) =
             s |> shouldEqual "CONSUMEPLUGIN_THINGS"
@@ -704,3 +704,87 @@ Required argument '--exact' received no value"""
         // Again, we don't try to detect that the user has missed out the desired argument to `--a`.
         exc.Message
         |> shouldEqual """Unable to process argument --c=hi as key --c and value hi"""
+
+    [<Test>]
+    let ``Type-level help text appears in help output`` () =
+        let getEnvVar (_ : string) = None
+
+        let exc =
+            Assert.Throws<exn> (fun () -> WithTypeHelp.parse' getEnvVar [ "--help" ] |> ignore<WithTypeHelp>)
+
+        exc.Message
+        |> shouldContainText
+            "Parse command-line arguments for a basic configuration. This help text appears before the argument list."
+
+        exc.Message
+        |> shouldContainText "--config-file  string : The configuration file path"
+
+        exc.Message |> shouldContainText "--verbose  bool : Enable verbose output"
+        exc.Message |> shouldContainText "--port  int32"
+
+    [<Test>]
+    let ``Type-level help text appears before field help`` () =
+        let getEnvVar (_ : string) = None
+
+        let exc =
+            Assert.Throws<exn> (fun () -> WithTypeHelp.parse' getEnvVar [ "--help" ] |> ignore<WithTypeHelp>)
+
+        // Verify that the type help appears before the field help
+        let typeHelpIndex =
+            exc.Message.IndexOf "Parse command-line arguments for a basic configuration"
+
+        let fieldHelpIndex = exc.Message.IndexOf "--config-file"
+
+        typeHelpIndex |> shouldBeSmallerThan fieldHelpIndex
+
+    [<Test>]
+    let ``Multiline type-level help text works`` () =
+        let getEnvVar (_ : string) = None
+
+        let exc =
+            Assert.Throws<exn> (fun () ->
+                WithMultilineTypeHelp.parse' getEnvVar [ "--help" ]
+                |> ignore<WithMultilineTypeHelp>
+            )
+
+        exc.Message |> shouldContainText "This is a multiline help text example."
+
+        exc.Message
+        |> shouldContainText "It spans multiple lines to test that multiline strings work correctly."
+
+        exc.Message
+        |> shouldContainText "You can use this to provide detailed documentation for your argument parser."
+
+        exc.Message |> shouldContainText "--input-file  string : Input file to process"
+        exc.Message |> shouldContainText "--output-dir  string : Output directory"
+        exc.Message |> shouldContainText "--force  bool"
+
+    [<Test>]
+    let ``Type-level help text appears in error messages`` () =
+        let getEnvVar (_ : string) = None
+
+        let exc =
+            Assert.Throws<exn> (fun () ->
+                WithTypeHelp.parse' getEnvVar [ "--unknown-arg" ; "value" ]
+                |> ignore<WithTypeHelp>
+            )
+
+        // Verify that the type help appears in error messages too
+        exc.Message
+        |> shouldContainText
+            "Parse command-line arguments for a basic configuration. This help text appears before the argument list."
+
+        exc.Message |> shouldContainText "--config-file"
+
+    [<Test>]
+    let ``Types without type-level help still work`` () =
+        let getEnvVar (_ : string) = None
+
+        let exc =
+            Assert.Throws<exn> (fun () -> Basic.parse' getEnvVar [ "--help" ] |> ignore<Basic>)
+
+        // Should not contain any type-level help, just the field help
+        exc.Message |> shouldContainText "--foo  int32 : This is a foo!"
+        exc.Message |> shouldContainText "--bar  string"
+        // Make sure there's no extra blank line at the beginning
+        exc.Message.StartsWith '\n' |> shouldEqual false

WoofWare.Myriad.Plugins.Test/TestArgParser/TestArgParserNegation.fs

@@ -0,0 +1,372 @@
+namespace WoofWare.Myriad.Plugins.Test
+
+open System.Threading
+open NUnit.Framework
+open FsUnitTyped
+open ConsumePlugin
+
+[<TestFixture>]
+module TestArgParserNegation =
+
+    [<Test>]
+    let ``Boolean field with ArgumentNegateWithPrefix: --foo sets to true`` () =
+        let getEnvVar (_ : string) = failwith "should not call"
+
+        let result = BoolNegation.parse' getEnvVar [ "--enable-feature" ]
+
+        result.EnableFeature |> shouldEqual true
+
+    [<Test>]
+    let ``Boolean field with ArgumentNegateWithPrefix: --foo=true sets to true`` () =
+        let getEnvVar (_ : string) = failwith "should not call"
+
+        let result = BoolNegation.parse' getEnvVar [ "--enable-feature=true" ]
+
+        result.EnableFeature |> shouldEqual true
+
+    [<Test>]
+    let ``Boolean field with ArgumentNegateWithPrefix: --foo true sets to true`` () =
+        let getEnvVar (_ : string) = failwith "should not call"
+
+        let result = BoolNegation.parse' getEnvVar [ "--enable-feature" ; "true" ]
+
+        result.EnableFeature |> shouldEqual true
+
+    [<Test>]
+    let ``Boolean field with ArgumentNegateWithPrefix: --foo=false sets to false`` () =
+        let getEnvVar (_ : string) = failwith "should not call"
+
+        let result = BoolNegation.parse' getEnvVar [ "--enable-feature=false" ]
+
+        result.EnableFeature |> shouldEqual false
+
+    [<Test>]
+    let ``Boolean field with ArgumentNegateWithPrefix: --foo false sets to false`` () =
+        let getEnvVar (_ : string) = failwith "should not call"
+
+        let result = BoolNegation.parse' getEnvVar [ "--enable-feature" ; "false" ]
+
+        result.EnableFeature |> shouldEqual false
+
+    [<Test>]
+    let ``Boolean field with ArgumentNegateWithPrefix: --no-foo sets to false`` () =
+        let getEnvVar (_ : string) = failwith "should not call"
+
+        let result = BoolNegation.parse' getEnvVar [ "--no-enable-feature" ]
+
+        result.EnableFeature |> shouldEqual false
+
+    [<Test>]
+    let ``Boolean field with ArgumentNegateWithPrefix: --no-foo=true sets to false`` () =
+        let getEnvVar (_ : string) = failwith "should not call"
+
+        let result = BoolNegation.parse' getEnvVar [ "--no-enable-feature=true" ]
+
+        result.EnableFeature |> shouldEqual false
+
+    [<Test>]
+    let ``Boolean field with ArgumentNegateWithPrefix: --no-foo true sets to false`` () =
+        let getEnvVar (_ : string) = failwith "should not call"
+
+        let result = BoolNegation.parse' getEnvVar [ "--no-enable-feature" ; "true" ]
+
+        result.EnableFeature |> shouldEqual false
+
+    [<Test>]
+    let ``Boolean field with ArgumentNegateWithPrefix: --no-foo=false sets to true`` () =
+        let getEnvVar (_ : string) = failwith "should not call"
+
+        let result = BoolNegation.parse' getEnvVar [ "--no-enable-feature=false" ]
+
+        result.EnableFeature |> shouldEqual true
+
+    [<Test>]
+    let ``Boolean field with ArgumentNegateWithPrefix: --no-foo false sets to true`` () =
+        let getEnvVar (_ : string) = failwith "should not call"
+
+        let result = BoolNegation.parse' getEnvVar [ "--no-enable-feature" ; "false" ]
+
+        result.EnableFeature |> shouldEqual true
+
+    [<Test>]
+    let ``Flag DU with ArgumentNegateWithPrefix: --dry-run sets to Dry`` () =
+        let getEnvVar (_ : string) = failwith "should not call"
+
+        let result = FlagNegation.parse' getEnvVar [ "--dry-run" ]
+
+        result.DryRun |> shouldEqual TestDryRunMode.Dry
+
+    [<Test>]
+    let ``Flag DU with ArgumentNegateWithPrefix: --dry-run=true sets to Dry`` () =
+        let getEnvVar (_ : string) = failwith "should not call"
+
+        let result = FlagNegation.parse' getEnvVar [ "--dry-run=true" ]
+
+        result.DryRun |> shouldEqual TestDryRunMode.Dry
+
+    [<Test>]
+    let ``Flag DU with ArgumentNegateWithPrefix: --dry-run true sets to Dry`` () =
+        let getEnvVar (_ : string) = failwith "should not call"
+
+        let result = FlagNegation.parse' getEnvVar [ "--dry-run" ; "true" ]
+
+        result.DryRun |> shouldEqual TestDryRunMode.Dry
+
+    [<Test>]
+    let ``Flag DU with ArgumentNegateWithPrefix: --dry-run=false sets to Wet`` () =
+        let getEnvVar (_ : string) = failwith "should not call"
+
+        let result = FlagNegation.parse' getEnvVar [ "--dry-run=false" ]
+
+        result.DryRun |> shouldEqual TestDryRunMode.Wet
+
+    [<Test>]
+    let ``Flag DU with ArgumentNegateWithPrefix: --dry-run false sets to Wet`` () =
+        let getEnvVar (_ : string) = failwith "should not call"
+
+        let result = FlagNegation.parse' getEnvVar [ "--dry-run" ; "false" ]
+
+        result.DryRun |> shouldEqual TestDryRunMode.Wet
+
+    [<Test>]
+    let ``Flag DU with ArgumentNegateWithPrefix: --no-dry-run sets to Wet`` () =
+        let getEnvVar (_ : string) = failwith "should not call"
+
+        let result = FlagNegation.parse' getEnvVar [ "--no-dry-run" ]
+
+        result.DryRun |> shouldEqual TestDryRunMode.Wet
+
+    [<Test>]
+    let ``Flag DU with ArgumentNegateWithPrefix: --no-dry-run=true sets to Wet`` () =
+        let getEnvVar (_ : string) = failwith "should not call"
+
+        let result = FlagNegation.parse' getEnvVar [ "--no-dry-run=true" ]
+
+        result.DryRun |> shouldEqual TestDryRunMode.Wet
+
+    [<Test>]
+    let ``Flag DU with ArgumentNegateWithPrefix: --no-dry-run true sets to Wet`` () =
+        let getEnvVar (_ : string) = failwith "should not call"
+
+        let result = FlagNegation.parse' getEnvVar [ "--no-dry-run" ; "true" ]
+
+        result.DryRun |> shouldEqual TestDryRunMode.Wet
+
+    [<Test>]
+    let ``Flag DU with ArgumentNegateWithPrefix: --no-dry-run=false sets to Dry`` () =
+        let getEnvVar (_ : string) = failwith "should not call"
+
+        let result = FlagNegation.parse' getEnvVar [ "--no-dry-run=false" ]
+
+        result.DryRun |> shouldEqual TestDryRunMode.Dry
+
+    [<Test>]
+    let ``Flag DU with ArgumentNegateWithPrefix: --no-dry-run false sets to Dry`` () =
+        let getEnvVar (_ : string) = failwith "should not call"
+
+        let result = FlagNegation.parse' getEnvVar [ "--no-dry-run" ; "false" ]
+
+        result.DryRun |> shouldEqual TestDryRunMode.Dry
+
+    [<Test>]
+    let ``ArgumentNegateWithPrefix works with multiple ArgumentLongForm: --verbose`` () =
+        let getEnvVar (_ : string) = failwith "should not call"
+
+        let result = MultipleFormsNegation.parse' getEnvVar [ "--verbose" ]
+
+        result.VerboseMode |> shouldEqual true
+
+    [<Test>]
+    let ``ArgumentNegateWithPrefix works with multiple ArgumentLongForm: --v`` () =
+        let getEnvVar (_ : string) = failwith "should not call"
+
+        let result = MultipleFormsNegation.parse' getEnvVar [ "--v" ]
+
+        result.VerboseMode |> shouldEqual true
+
+    [<Test>]
+    let ``ArgumentNegateWithPrefix works with multiple ArgumentLongForm: --no-verbose`` () =
+        let getEnvVar (_ : string) = failwith "should not call"
+
+        let result = MultipleFormsNegation.parse' getEnvVar [ "--no-verbose" ]
+
+        result.VerboseMode |> shouldEqual false
+
+    [<Test>]
+    let ``ArgumentNegateWithPrefix works with multiple ArgumentLongForm: --no-v`` () =
+        let getEnvVar (_ : string) = failwith "should not call"
+
+        let result = MultipleFormsNegation.parse' getEnvVar [ "--no-v" ]
+
+        result.VerboseMode |> shouldEqual false
+
+    [<Test>]
+    let ``ArgumentNegateWithPrefix works with multiple ArgumentLongForm: --verbose=false`` () =
+        let getEnvVar (_ : string) = failwith "should not call"
+
+        let result = MultipleFormsNegation.parse' getEnvVar [ "--verbose=false" ]
+
+        result.VerboseMode |> shouldEqual false
+
+    [<Test>]
+    let ``ArgumentNegateWithPrefix works with multiple ArgumentLongForm: --no-v=false`` () =
+        let getEnvVar (_ : string) = failwith "should not call"
+
+        let result = MultipleFormsNegation.parse' getEnvVar [ "--no-v=false" ]
+
+        result.VerboseMode |> shouldEqual true
+
+    [<Test>]
+    let ``Help text shows both standard and negated forms for boolean`` () =
+        let getEnvVar (_ : string) = failwith "do not call"
+
+        let exc =
+            Assert.Throws<exn> (fun () -> BoolNegation.parse' getEnvVar [ "--help" ] |> ignore<BoolNegation>)
+
+        exc.Message
+        |> shouldEqual
+            """Help text requested.
+--enable-feature / --no-enable-feature  bool"""
+
+    [<Test>]
+    let ``Help text shows both standard and negated forms for flag DU`` () =
+        let getEnvVar (_ : string) = failwith "do not call"
+
+        let exc =
+            Assert.Throws<exn> (fun () -> FlagNegation.parse' getEnvVar [ "--help" ] |> ignore<FlagNegation>)
+
+        exc.Message
+        |> shouldEqual
+            """Help text requested.
+--dry-run / --no-dry-run  bool"""
+
+    [<Test>]
+    let ``Help text with multiple long forms shows all variants`` () =
+        let getEnvVar (_ : string) = failwith "do not call"
+
+        let exc =
+            Assert.Throws<exn> (fun () ->
+                MultipleFormsNegation.parse' getEnvVar [ "--help" ]
+                |> ignore<MultipleFormsNegation>
+            )
+
+        exc.Message
+        |> shouldEqual
+            """Help text requested.
+--verbose / --v / --no-verbose / --no-v  bool"""
+
+    [<Test>]
+    let ``Multiple occurrences error: --foo and --no-foo both supplied`` () =
+        let getEnvVar (_ : string) = failwith "should not call"
+
+        let exc =
+            Assert.Throws<exn> (fun () ->
+                BoolNegation.parse' getEnvVar [ "--enable-feature" ; "--no-enable-feature" ]
+                |> ignore<BoolNegation>
+            )
+
+        // Should report as duplicate argument
+        exc.Message |> shouldContainText "supplied multiple times"
+
+    [<Test>]
+    let ``Multiple occurrences error: --no-foo and --foo both supplied`` () =
+        let getEnvVar (_ : string) = failwith "should not call"
+
+        let exc =
+            Assert.Throws<exn> (fun () ->
+                BoolNegation.parse' getEnvVar [ "--no-enable-feature" ; "--enable-feature" ]
+                |> ignore<BoolNegation>
+            )
+
+        // Should report as duplicate argument
+        exc.Message |> shouldContainText "supplied multiple times"
+
+    [<Test>]
+    let ``Multiple occurrences error: --foo=true and --no-foo=false both supplied`` () =
+        let getEnvVar (_ : string) = failwith "should not call"
+
+        let exc =
+            Assert.Throws<exn> (fun () ->
+                BoolNegation.parse' getEnvVar [ "--enable-feature=true" ; "--no-enable-feature=false" ]
+                |> ignore<BoolNegation>
+            )
+
+        // Should report as duplicate argument
+        exc.Message |> shouldContainText "supplied multiple times"
+
+    [<Test>]
+    let ``CombinedFeatures: verbose with default value works with negation`` () =
+        let getEnvVar (_ : string) = failwith "should not call"
+
+        let result = CombinedFeatures.parse' getEnvVar [ "--debug" ; "--normal-bool" ]
+
+        result.Verbose |> shouldEqual (Choice2Of2 false)
+        result.Debug |> shouldEqual true
+        result.NormalBool |> shouldEqual true
+
+    [<Test>]
+    let ``CombinedFeatures: can override default with --verbose`` () =
+        let getEnvVar (_ : string) = failwith "should not call"
+
+        let result =
+            CombinedFeatures.parse' getEnvVar [ "--verbose" ; "--debug" ; "--normal-bool" ]
+
+        result.Verbose |> shouldEqual (Choice1Of2 true)
+        result.Debug |> shouldEqual true
+        result.NormalBool |> shouldEqual true
+
+    [<Test>]
+    let ``CombinedFeatures: can override default with --no-verbose`` () =
+        let getEnvVar (_ : string) = failwith "should not call"
+
+        let result =
+            CombinedFeatures.parse' getEnvVar [ "--no-verbose" ; "--debug" ; "--normal-bool" ]
+
+        result.Verbose |> shouldEqual (Choice1Of2 false)
+        result.Debug |> shouldEqual true
+        result.NormalBool |> shouldEqual true
+
+    [<Test>]
+    let ``CombinedFeatures: --no-debug sets debug to false`` () =
+        let getEnvVar (_ : string) = failwith "should not call"
+
+        let result = CombinedFeatures.parse' getEnvVar [ "--no-debug" ; "--normal-bool" ]
+
+        result.Debug |> shouldEqual false
+
+    [<Test>]
+    let ``CombinedFeatures: help text shows negation for fields with attribute`` () =
+        let getEnvVar (_ : string) = failwith "do not call"
+
+        let exc =
+            Assert.Throws<exn> (fun () -> CombinedFeatures.parse' getEnvVar [ "--help" ] |> ignore<CombinedFeatures>)
+
+        // Verbose and Debug should have --no- forms, NormalBool should not
+        exc.Message |> shouldContainText "--verbose / --no-verbose"
+        exc.Message |> shouldContainText "--debug / --no-debug"
+        exc.Message |> shouldContainText "--normal-bool  bool"
+        exc.Message |> shouldNotContainText "--no-normal-bool"
+
+    [<Test>]
+    let ``Case insensitivity: --NO-ENABLE-FEATURE works`` () =
+        let getEnvVar (_ : string) = failwith "should not call"
+
+        let result = BoolNegation.parse' getEnvVar [ "--NO-ENABLE-FEATURE" ]
+
+        result.EnableFeature |> shouldEqual false
+
+    [<Test>]
+    let ``Case insensitivity: --No-Enable-Feature works`` () =
+        let getEnvVar (_ : string) = failwith "should not call"
+
+        let result = BoolNegation.parse' getEnvVar [ "--No-Enable-Feature" ]
+
+        result.EnableFeature |> shouldEqual false
+
+    [<Test>]
+    let ``Case insensitivity: --NO-DRY-RUN works`` () =
+        let getEnvVar (_ : string) = failwith "should not call"
+
+        let result = FlagNegation.parse' getEnvVar [ "--NO-DRY-RUN" ]
+
+        result.DryRun |> shouldEqual TestDryRunMode.Wet

WoofWare.Myriad.Plugins.Test/TestCapturingMockGenerator/TestCapturingMockGenerator.fs

@@ -70,3 +70,63 @@ module TestCapturingMockGenerator =
                 bar = 3
                 Arg1 = "hello"
             }
+
+    [<Test>]
+    let ``Example of use IAsyncDisposable`` () =
+        let mock' =
+            { TypeWithAsyncDisposableMock.Empty () with
+                Mem1 = fun i -> async { return Option.toArray i }
+                Mem2 = fun () -> async { return [||] }
+            }
+
+        let mock = mock' :> TypeWithAsyncDisposable
+
+        mock.Mem1 (Some "hi") |> Async.RunSynchronously |> shouldEqual [| "hi" |]
+        mock.Mem2 () |> Async.RunSynchronously |> shouldEqual [||]
+
+        // Test that DisposeAsync returns a completed ValueTask
+        let asyncDisposable = mock :> IAsyncDisposable
+        let valueTask = asyncDisposable.DisposeAsync ()
+        valueTask.IsCompleted |> shouldEqual true
+
+        // Verify calls were captured
+        lock mock'.Calls.Mem1 (fun () -> Seq.toList mock'.Calls.Mem1)
+        |> List.exactlyOne
+        |> shouldEqual (Some "hi")
+
+        lock mock'.Calls.Mem2 (fun () -> Seq.toList mock'.Calls.Mem2)
+        |> List.exactlyOne
+        |> shouldEqual ()
+
+    [<Test>]
+    let ``Example of use: Both IDisposable and IAsyncDisposable`` () =
+        let mutable disposed = false
+        let mutable disposedAsync = false
+
+        let mock' =
+            { TypeWithBothDisposablesMock.Empty () with
+                Dispose = fun () -> disposed <- true
+                DisposeAsync =
+                    fun () ->
+                        disposedAsync <- true
+                        System.Threading.Tasks.ValueTask ()
+                Mem1 = fun s -> s.Length
+            }
+
+        let mock = mock' :> TypeWithBothDisposables
+
+        mock.Mem1 "hello" |> shouldEqual 5
+        mock.Mem1 "world" |> shouldEqual 5
+
+        // Test IDisposable.Dispose
+        (mock :> IDisposable).Dispose ()
+        disposed |> shouldEqual true
+
+        // Test IAsyncDisposable.DisposeAsync
+        let valueTask = (mock :> IAsyncDisposable).DisposeAsync ()
+        valueTask.IsCompleted |> shouldEqual true
+        disposedAsync |> shouldEqual true
+
+        // Verify calls were captured
+        lock mock'.Calls.Mem1 (fun () -> Seq.toList mock'.Calls.Mem1)
+        |> shouldEqual [ "hello" ; "world" ]

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

@@ -0,0 +1,51 @@
+namespace WoofWare.Myriad.Plugins.Test
+
+open System.Threading
+open NUnit.Framework
+open FsUnitTyped
+open ConsumePluginNoAttr
+open FsCheck
+
+[<TestFixture>]
+module TestCataGeneratorNoAttr =
+    let idCata<'a, 'b> : TreeNoAttrCata<'a, 'b, _, _> =
+        {
+            TreeNoAttr =
+                { new TreeNoAttrCataCase<_, _, _, _> 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)
+                }
+            TreeBuilderNoAttr =
+                { new TreeBuilderNoAttrCataCase<_, _, _, _> with
+                    member _.Child x = Child x
+                    member _.Parent x = Parent x
+                }
+        }
+
+    [<Test>]
+    let ``Example`` () =
+        let x =
+            TreeNoAttr.Pair (
+                TreeNoAttr.Const (ConstNoAttr.Verbatim 0, "hi"),
+                TreeNoAttr.Const (ConstNoAttr.String "", "bye"),
+                PairOpKindNoAttr.ThenDoSeq
+            )
+
+        TreeNoAttrCata.runTreeNoAttr idCata x |> shouldEqual x
+
+
+    [<Test>]
+    let ``Cata works`` () =
+        let builderCases = ref 0
+
+        let property (x : TreeNoAttr<int, string>) =
+            match x with
+            | TreeNoAttr.Builder _ -> Interlocked.Increment builderCases |> ignore
+            | _ -> ()
+
+            TreeNoAttrCata.runTreeNoAttr idCata x = x
+
+        Check.QuickThrowOnFailure property
+        builderCases.Value |> shouldBeGreaterThan 10

WoofWare.Myriad.Plugins.Test/TestMockGenerator/TestMockGenerator.fs

@@ -47,3 +47,45 @@ module TestMockGenerator =
         mock.Mem1 (Some "hi") |> Async.RunSynchronously |> shouldEqual [| "hi" |]
 
         mock.Prop1 |> shouldEqual 44
+
+    [<Test>]
+    let ``Example of use: IAsyncDisposable`` () =
+        let mock : TypeWithAsyncDisposable =
+            { TypeWithAsyncDisposableMock.Empty with
+                Mem1 = fun i -> async { return Option.toArray i }
+            }
+            :> _
+
+        mock.Mem1 (Some "hi") |> Async.RunSynchronously |> shouldEqual [| "hi" |]
+
+        // Test that DisposeAsync returns a completed ValueTask
+        let asyncDisposable = mock :> IAsyncDisposable
+        let valueTask = asyncDisposable.DisposeAsync ()
+        valueTask.IsCompleted |> shouldEqual true
+
+    [<Test>]
+    let ``Example of use: Both IDisposable and IAsyncDisposable`` () =
+        let mutable disposed = false
+        let mutable disposedAsync = false
+
+        let mock : TypeWithBothDisposables =
+            { TypeWithBothDisposablesMock.Empty with
+                Dispose = fun () -> disposed <- true
+                DisposeAsync =
+                    fun () ->
+                        disposedAsync <- true
+                        System.Threading.Tasks.ValueTask ()
+                Mem1 = fun s -> s.Length
+            }
+            :> _
+
+        mock.Mem1 "hello" |> shouldEqual 5
+
+        // Test IDisposable.Dispose
+        (mock :> IDisposable).Dispose ()
+        disposed |> shouldEqual true
+
+        // Test IAsyncDisposable.DisposeAsync
+        let valueTask = (mock :> IAsyncDisposable).DisposeAsync ()
+        valueTask.IsCompleted |> shouldEqual true
+        disposedAsync |> shouldEqual true

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

@@ -9,7 +9,6 @@
       I have not yet seen a single instance where I care about this warning
     -->
     <NoWarn>$(NoWarn),NU1903</NoWarn>
-    <TestingPlatformDotnetTestSupport>true</TestingPlatformDotnetTestSupport>
   </PropertyGroup>
 
   <ItemGroup>
@@ -33,11 +32,13 @@
     <Compile Include="TestCapturingMockGenerator\TestCapturingMockGeneratorNoAttr.fs" />
     <Compile Include="TestJsonSerialize\TestJsonSerde.fs" />
     <Compile Include="TestCataGenerator\TestCataGenerator.fs" />
+    <Compile Include="TestCataGenerator\TestCataGeneratorNoAttr.fs" />
     <Compile Include="TestCataGenerator\TestDirectory.fs" />
     <Compile Include="TestCataGenerator\TestGift.fs" />
     <Compile Include="TestCataGenerator\TestMyList.fs" />
     <Compile Include="TestCataGenerator\TestMyList2.fs" />
     <Compile Include="TestArgParser\TestArgParser.fs" />
+    <Compile Include="TestArgParser\TestArgParserNegation.fs" />
     <Compile Include="TestSwagger\TestSwaggerParse.fs" />
     <Compile Include="TestSwagger\TestOpenApi3Parse.fs" />
     <EmbeddedResource Include="TestSwagger\api-with-examples.json" />
@@ -55,13 +56,13 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="ApiSurface" Version="5.0.2" />
+    <PackageReference Include="ApiSurface" Version="5.0.3" />
     <PackageReference Include="FsCheck" Version="3.3.2" />
     <PackageReference Include="FsUnit" Version="7.1.1" />
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="18.0.0" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="18.0.1" />
     <PackageReference Include="NUnit" Version="4.3.2" />
     <PackageReference Include="NUnit3TestAdapter" Version="5.2.0" />
-    <PackageReference Include="WoofWare.Expect" Version="0.8.4" />
+    <PackageReference Include="WoofWare.Expect" Version="0.8.5" />
   </ItemGroup>
 
   <ItemGroup>

WoofWare.Myriad.Plugins/ArgParserGenerator.fs

@@ -72,16 +72,38 @@ type private ParseFunction<'acc> =
         /// and choices and so on.
         TargetType : SynType
         Accumulation : 'acc
+        /// If true, this boolean/flag field accepts --no- prefix for negation (has [<ArgumentNegateWithPrefix>])
+        AcceptsNegation : bool
     }
 
     /// A SynExpr of type `string` which we can display to the user at generated-program runtime to display all
     /// the ways they can refer to this arg.
     member arg.HumanReadableArgForm : SynExpr =
-        let formatString = List.replicate arg.ArgForm.Length "--%s" |> String.concat " / "
+        if arg.AcceptsNegation then
+            // Include both standard and --no- variants
+            // E.g., "--foo / --bar / --no-foo / --no-bar"
+            let standardFormatString =
+                List.replicate arg.ArgForm.Length "--%s" |> String.concat " / "
 
-        (SynExpr.applyFunction (SynExpr.createIdent "sprintf") (SynExpr.CreateConst formatString), arg.ArgForm)
+            let negatedFormatString =
-        ||> List.fold SynExpr.applyFunction
+                List.replicate arg.ArgForm.Length "--no-%s" |> String.concat " / "
-        |> SynExpr.paren
+
+            let combinedFormatString = standardFormatString + " / " + negatedFormatString
+
+            // Apply all arg forms twice (once for standard, once for negated)
+            let allArgForms = arg.ArgForm @ arg.ArgForm
+
+            (SynExpr.applyFunction (SynExpr.createIdent "sprintf") (SynExpr.CreateConst combinedFormatString),
+             allArgForms)
+            ||> List.fold SynExpr.applyFunction
+            |> SynExpr.paren
+        else
+            // Standard behavior: just --foo / --bar
+            let formatString = List.replicate arg.ArgForm.Length "--%s" |> String.concat " / "
+
+            (SynExpr.applyFunction (SynExpr.createIdent "sprintf") (SynExpr.CreateConst formatString), arg.ArgForm)
+            ||> List.fold SynExpr.applyFunction
+            |> SynExpr.paren
 
 [<RequireQualifiedAccess>]
 type private ChoicePositional =
@@ -222,8 +244,8 @@ module private ParseTree =
             nonPos @ nonPos2, Some pos
 
         |> fun (nonPos, pos) ->
-            let duplicateArgs =
+            // Extract all arg form strings for validation
-                // This is best-effort. We can't necessarily detect all SynExprs here, but usually it'll be strings.
+            let allArgForms =
                 Option.toList (pos |> Option.map _.ArgForm) @ (nonPos |> List.map _.ArgForm)
                 |> Seq.concat
                 |> Seq.choose (fun expr ->
@@ -232,14 +254,57 @@ module private ParseTree =
                     | _ -> None
                 )
                 |> List.ofSeq
+
+            // Check for direct duplicates
+            let duplicateArgs =
+                allArgForms
                 |> List.groupBy id
                 |> List.choose (fun (key, v) -> if v.Length > 1 then Some key else None)
 
             match duplicateArgs with
-            | [] -> nonPos, pos
+            | dups when not dups.IsEmpty ->
-            | dups ->
                 let dups = dups |> String.concat " "
                 failwith $"Duplicate args detected! %s{dups}"
+            | _ ->
+
+            // Check for --no- prefix conflicts
+            // Build a map of arg names that have AcceptsNegation=true
+            let negatedForms =
+                nonPos
+                |> List.filter _.AcceptsNegation
+                |> List.collect (fun pf ->
+                    pf.ArgForm
+                    |> List.choose (fun expr ->
+                        match expr |> SynExpr.stripOptionalParen with
+                        | SynExpr.Const (SynConst.String (s, _, _), _) -> Some (pf.FieldName.idText, s)
+                        | _ -> None
+                    )
+                )
+                |> List.map (fun (fieldName, argForm) -> $"no-%s{argForm}", fieldName)
+                |> Map.ofList
+
+            // Check if any existing arg form conflicts with a --no- variant
+            let conflicts =
+                allArgForms
+                |> List.choose (fun argForm ->
+                    match negatedForms.TryFind argForm with
+                    | Some fieldWithNegation -> Some (argForm, fieldWithNegation)
+                    | None -> None
+                )
+
+            match conflicts with
+            | [] -> ()
+            | conflicts ->
+                let conflictMessages =
+                    conflicts
+                    |> List.map (fun (argForm, fieldWithNegation) ->
+                        $"Argument name conflict: '--%s{argForm}' collides with the --no- variant of field '%s{fieldWithNegation}' (which has [<ArgumentNegateWithPrefix>])"
+                    )
+                    |> String.concat "\n"
+
+                failwith $"Conflicting argument names detected:\n%s{conflictMessages}"
+
+            nonPos, pos
 
     /// Build the return value.
     let rec instantiate<'a> (tree : ParseTree<'a>) : SynExpr =
@@ -615,6 +680,7 @@ module internal ArgParserGenerator =
                             ArgForm = longForms
                             Help = helpText
                             BoolCases = isBoolLike
+                            AcceptsNegation = false
                         }
                         |> fun t -> ParseTree.PositionalLeaf (t, Teq.refl)
                     | Accumulation.List Accumulation.Required ->
@@ -627,6 +693,7 @@ module internal ArgParserGenerator =
                             ArgForm = longForms
                             Help = helpText
                             BoolCases = isBoolLike
+                            AcceptsNegation = false
                         }
                         |> fun t -> ParseTree.PositionalLeaf (t, Teq.refl)
                     | Accumulation.Choice _
@@ -651,6 +718,27 @@ module internal ArgParserGenerator =
                             Some (Choice2Of2 ())
                         | parseTy -> identifyAsFlag flagDus parseTy |> Option.map Choice1Of2
 
+                    let hasNegateAttr =
+                        attrs
+                        |> List.exists (fun attr ->
+                            match attr.TypeName with
+                            | SynLongIdent.SynLongIdent (ident, _, _) ->
+                                match (List.last ident).idText with
+                                | "ArgumentNegateWithPrefixAttribute"
+                                | "ArgumentNegateWithPrefix" -> true
+                                | _ -> false
+                        )
+
+                    let acceptsNegation =
+                        if hasNegateAttr then
+                            match isBoolLike with
+                            | Some _ -> true
+                            | None ->
+                                failwith
+                                    $"[<ArgumentNegateWithPrefix>] can only be applied to boolean or flag DU fields, but was applied to field %s{ident.idText} of type %O{fieldType}"
+                        else
+                            false
+
                     {
                         FieldName = ident
                         Parser = parser
@@ -660,6 +748,7 @@ module internal ArgParserGenerator =
                         ArgForm = longForms
                         Help = helpText
                         BoolCases = isBoolLike
+                        AcceptsNegation = acceptsNegation
                     }
                     |> fun t -> ParseTree.NonPositionalLeaf (t, Teq.refl)
                     |> ParseTreeCrate.make
@@ -680,6 +769,7 @@ module internal ArgParserGenerator =
 
     /// let helpText : string = ...
     let private helpText
+        (typeHelp : SynExpr option)
         (typeName : Ident)
         (positional : ParseFunctionPositional option)
         (args : ParseFunctionNonPositional list)
@@ -761,18 +851,61 @@ module internal ArgParserGenerator =
             |> SynExpr.applyTo helpText
             |> SynExpr.paren
 
-        args
+        let fieldHelp =
-        |> List.map (toPrintable describeNonPositional)
+            args
-        |> fun l ->
+            |> List.map (toPrintable describeNonPositional)
-            match positional with
+            |> fun l ->
-            | None -> l
+                match positional with
-            | Some pos -> l @ [ toPrintable describePositional pos ]
+                | None -> l
+                | Some pos -> l @ [ toPrintable describePositional pos ]
+
+        let allHelp =
+            match typeHelp with
+            | Some helpExpr ->
+                // Prepend type help, followed by blank line, then field help
+                [ helpExpr ; SynExpr.CreateConst "" ] @ fieldHelp
+            | None ->
+                // No type help, just field help
+                fieldHelp
+
+        allHelp
         |> SynExpr.listLiteral
         |> SynExpr.pipeThroughFunction (
             SynExpr.applyFunction (SynExpr.createLongIdent [ "String" ; "concat" ]) (SynExpr.CreateConst @"\n")
         )
         |> SynBinding.basic [ Ident.create "helpText" ] [ SynPat.unit ]
 
+    /// Helper to create a negated parser for boolean/flag fields.
+    /// Returns a SynExpr that represents: string -> (negated bool or negated flag DU)
+    /// For booleans: `fun x -> not (Boolean.Parse x)`
+    /// For flag DUs: `fun x -> FlagDu.FromBoolean flagDu (not (Boolean.Parse x))`
+    let private createNegatedParser (arg : ParseFunction<'acc>) : SynExpr =
+        match arg.BoolCases with
+        | None -> failwith $"LOGIC ERROR: createNegatedParser called on non-boolean field %s{arg.FieldName.idText}"
+        | Some (Choice2Of2 ()) ->
+            // Boolean: parse and negate
+            // fun x -> not (System.Boolean.Parse x)
+            let parseExpr =
+                SynExpr.createIdent "x"
+                |> SynExpr.applyFunction (SynExpr.createLongIdent [ "System" ; "Boolean" ; "Parse" ])
+                |> SynExpr.paren
+
+            parseExpr
+            |> SynExpr.applyFunction (SynExpr.createIdent "not")
+            |> SynExpr.createLambda "x"
+        | Some (Choice1Of2 flagDu) ->
+            // Flag DU: parse as bool, negate, then convert to flag DU
+            // fun x -> x |> System.Boolean.Parse |> not |> FlagDu.FromBoolean flagDu
+            let parseExpr =
+                SynExpr.createIdent "x"
+                |> SynExpr.applyFunction (SynExpr.createLongIdent [ "System" ; "Boolean" ; "Parse" ])
+                |> SynExpr.paren
+
+            parseExpr
+            |> SynExpr.applyFunction (SynExpr.createIdent "not")
+            |> FlagDu.FromBoolean flagDu
+            |> SynExpr.createLambda "x"
+
     /// `let processKeyValue (key : string) (value : string) : Result<unit, string option> = ...`
     /// Returns a possible error.
     /// A parse failure might not be fatal (e.g. maybe the input was optionally of arity 0, and we failed to do
@@ -786,109 +919,209 @@ module internal ArgParserGenerator =
         let args =
             args
             |> List.map (fun arg ->
-                match arg.Accumulation with
+                let assignmentExpr =
-                | Accumulation.Required
+                    match arg.Accumulation with
-                | Accumulation.Choice _
+                    | Accumulation.Required
-                | Accumulation.Optional ->
+                    | Accumulation.Choice _
-                    let multipleErrorMessage =
+                    | Accumulation.Optional ->
-                        SynExpr.createIdent "sprintf"
+                        let multipleErrorMessage =
-                        |> SynExpr.applyTo (SynExpr.CreateConst "Argument '%s' was supplied multiple times: %s and %s")
+                            SynExpr.createIdent "sprintf"
-                        |> SynExpr.applyTo arg.HumanReadableArgForm
+                            |> SynExpr.applyTo (
-                        |> SynExpr.applyTo (SynExpr.createIdent "x" |> SynExpr.callMethod "ToString" |> SynExpr.paren)
+                                SynExpr.CreateConst "Argument '%s' was supplied multiple times: %s and %s"
-                        |> SynExpr.applyTo (
+                            )
-                            SynExpr.createIdent "value" |> SynExpr.callMethod "ToString" |> SynExpr.paren
+                            |> SynExpr.applyTo arg.HumanReadableArgForm
-                        )
+                            |> SynExpr.applyTo (
+                                SynExpr.createIdent "x" |> SynExpr.callMethod "ToString" |> SynExpr.paren
+                            )
+                            |> SynExpr.applyTo (
+                                SynExpr.createIdent "value" |> SynExpr.callMethod "ToString" |> SynExpr.paren
+                            )
 
-                    let performAssignment =
+                        let performAssignment =
+                            [
+                                SynExpr.createIdent "value"
+                                |> SynExpr.pipeThroughFunction arg.Parser
+                                |> SynExpr.pipeThroughFunction (SynExpr.createIdent "Some")
+                                |> SynExpr.assign (SynLongIdent.createI arg.TargetVariable)
+
+                                SynExpr.applyFunction (SynExpr.createIdent "Ok") (SynExpr.CreateConst ())
+                            ]
+                            |> SynExpr.sequential
+
+                        [
+                            SynMatchClause.create
+                                (SynPat.nameWithArgs "Some" [ SynPat.named "x" ])
+                                (SynExpr.sequential
+                                    [
+                                        multipleErrorMessage
+                                        |> SynExpr.pipeThroughFunction (
+                                            SynExpr.dotGet "Add" (SynExpr.createIdent' argParseErrors)
+                                        )
+                                        SynExpr.applyFunction (SynExpr.createIdent "Ok") (SynExpr.CreateConst ())
+                                    ])
+                            SynMatchClause.create
+                                (SynPat.named "None")
+                                (SynExpr.pipeThroughTryWith
+                                    SynPat.anon
+                                    (SynExpr.createLongIdent [ "exc" ; "Message" ]
+                                     |> SynExpr.pipeThroughFunction (SynExpr.createIdent "Some")
+                                     |> SynExpr.pipeThroughFunction (SynExpr.createIdent "Error"))
+                                    performAssignment)
+                        ]
+                        |> SynExpr.createMatch (SynExpr.createIdent' arg.TargetVariable)
+                    | Accumulation.List (Accumulation.List _)
+                    | Accumulation.List Accumulation.Optional
+                    | Accumulation.List (Accumulation.Choice _) ->
+                        failwith
+                            "WoofWare.Myriad invariant violated: expected a list to contain only a Required accumulation. Non-positional lists cannot be optional or Choice, nor can they themselves contain lists."
+                    | Accumulation.List Accumulation.Required ->
                         [
                             SynExpr.createIdent "value"
                             |> SynExpr.pipeThroughFunction arg.Parser
-                            |> SynExpr.pipeThroughFunction (SynExpr.createIdent "Some")
+                            |> SynExpr.pipeThroughFunction (
-                            |> SynExpr.assign (SynLongIdent.createI arg.TargetVariable)
+                                SynExpr.createLongIdent' [ arg.TargetVariable ; Ident.create "Add" ]
-
+                            )
-                            SynExpr.applyFunction (SynExpr.createIdent "Ok") (SynExpr.CreateConst ())
+                            SynExpr.CreateConst () |> SynExpr.pipeThroughFunction (SynExpr.createIdent "Ok")
                         ]
                         |> SynExpr.sequential
 
-                    [
+                // Return (argForms, assignmentExpr), argMetadata
-                        SynMatchClause.create
+                (arg.ArgForm, assignmentExpr), Some arg
-                            (SynPat.nameWithArgs "Some" [ SynPat.named "x" ])
-                            (SynExpr.sequential
-                                [
-                                    multipleErrorMessage
-                                    |> SynExpr.pipeThroughFunction (
-                                        SynExpr.dotGet "Add" (SynExpr.createIdent' argParseErrors)
-                                    )
-                                    SynExpr.applyFunction (SynExpr.createIdent "Ok") (SynExpr.CreateConst ())
-                                ])
-                        SynMatchClause.create
-                            (SynPat.named "None")
-                            (SynExpr.pipeThroughTryWith
-                                SynPat.anon
-                                (SynExpr.createLongIdent [ "exc" ; "Message" ]
-                                 |> SynExpr.pipeThroughFunction (SynExpr.createIdent "Some")
-                                 |> SynExpr.pipeThroughFunction (SynExpr.createIdent "Error"))
-                                performAssignment)
-                    ]
-                    |> SynExpr.createMatch (SynExpr.createIdent' arg.TargetVariable)
-                | Accumulation.List (Accumulation.List _)
-                | Accumulation.List Accumulation.Optional
-                | Accumulation.List (Accumulation.Choice _) ->
-                    failwith
-                        "WoofWare.Myriad invariant violated: expected a list to contain only a Required accumulation. Non-positional lists cannot be optional or Choice, nor can they themselves contain lists."
-                | Accumulation.List Accumulation.Required ->
-                    [
-                        SynExpr.createIdent "value"
-                        |> SynExpr.pipeThroughFunction arg.Parser
-                        |> SynExpr.pipeThroughFunction (
-                            SynExpr.createLongIdent' [ arg.TargetVariable ; Ident.create "Add" ]
-                        )
-                        SynExpr.CreateConst () |> SynExpr.pipeThroughFunction (SynExpr.createIdent "Ok")
-                    ]
-                    |> SynExpr.sequential
-                |> fun expr -> arg.ArgForm, expr
             )
 
         let posArg =
             match pos with
             | None -> []
             | Some pos ->
-                [
+                let posExpr =
-                    SynExpr.createIdent "value"
+                    [
-                    |> SynExpr.pipeThroughFunction pos.Parser
+                        SynExpr.createIdent "value"
-                    |> fun p ->
+                        |> SynExpr.pipeThroughFunction pos.Parser
-                        match pos.Accumulation with
+                        |> fun p ->
-                        | ChoicePositional.Choice _ ->
+                            match pos.Accumulation with
-                            p |> SynExpr.pipeThroughFunction (SynExpr.createIdent "Choice1Of2")
+                            | ChoicePositional.Choice _ ->
-                        | ChoicePositional.Normal _ -> p
+                                p |> SynExpr.pipeThroughFunction (SynExpr.createIdent "Choice1Of2")
-                    |> SynExpr.pipeThroughFunction (
+                            | ChoicePositional.Normal _ -> p
-                        SynExpr.createLongIdent' [ pos.TargetVariable ; Ident.create "Add" ]
+                        |> SynExpr.pipeThroughFunction (
-                    )
+                            SynExpr.createLongIdent' [ pos.TargetVariable ; Ident.create "Add" ]
-                    SynExpr.CreateConst () |> SynExpr.pipeThroughFunction (SynExpr.createIdent "Ok")
+                        )
-                ]
+                        SynExpr.CreateConst () |> SynExpr.pipeThroughFunction (SynExpr.createIdent "Ok")
-                |> SynExpr.sequential
+                    ]
-                |> fun expr -> pos.ArgForm, expr
+                    |> SynExpr.sequential
-                |> List.singleton
+
+                // Positional args don't support negation, so metadata is None
+                [ (pos.ArgForm, posExpr), None ]
 
         (SynExpr.applyFunction (SynExpr.createIdent "Error") (SynExpr.createIdent "None"), posArg @ args)
-        ||> List.fold (fun finalBranch (argForm, arg) ->
+        ||> List.fold (fun finalBranch ((argForm, arg), argMetadata) ->
             (finalBranch, argForm)
             ||> List.fold (fun finalBranch argForm ->
-                arg
+                // Standard match: --argForm
-                |> SynExpr.ifThenElse
+                let standardMatch =
-                    (SynExpr.applyFunction
+                    arg
-                        (SynExpr.createLongIdent [ "System" ; "String" ; "Equals" ])
+                    |> SynExpr.ifThenElse
-                        (SynExpr.tuple
+                        (SynExpr.applyFunction
+                            (SynExpr.createLongIdent [ "System" ; "String" ; "Equals" ])
+                            (SynExpr.tuple
+                                [
+                                    SynExpr.createIdent "key"
+                                    SynExpr.applyFunction
+                                        (SynExpr.applyFunction
+                                            (SynExpr.createIdent "sprintf")
+                                            (SynExpr.CreateConst "--%s"))
+                                        argForm
+                                    SynExpr.createLongIdent [ "System" ; "StringComparison" ; "OrdinalIgnoreCase" ]
+                                ]))
+                        finalBranch
+
+                // If this arg accepts negation, also match --no-argForm
+                match argMetadata with
+                | None -> standardMatch
+                | Some (parseFn : ParseFunctionNonPositional) when parseFn.AcceptsNegation ->
+                    // Create negated assignment (same structure as `arg` but with negated parser)
+                    let negatedParser = createNegatedParser parseFn
+
+                    let negatedArg =
+                        match parseFn.Accumulation with
+                        | Accumulation.Required
+                        | Accumulation.Choice _
+                        | Accumulation.Optional ->
+                            let multipleErrorMessage =
+                                SynExpr.createIdent "sprintf"
+                                |> SynExpr.applyTo (
+                                    SynExpr.CreateConst "Argument '%s' was supplied multiple times: %s and %s"
+                                )
+                                |> SynExpr.applyTo parseFn.HumanReadableArgForm
+                                |> SynExpr.applyTo (
+                                    SynExpr.createIdent "x" |> SynExpr.callMethod "ToString" |> SynExpr.paren
+                                )
+                                |> SynExpr.applyTo (
+                                    SynExpr.createIdent "value" |> SynExpr.callMethod "ToString" |> SynExpr.paren
+                                )
+
+                            let performNegatedAssignment =
+                                [
+                                    SynExpr.createIdent "value"
+                                    |> SynExpr.pipeThroughFunction negatedParser
+                                    |> SynExpr.pipeThroughFunction (SynExpr.createIdent "Some")
+                                    |> SynExpr.assign (SynLongIdent.createI parseFn.TargetVariable)
+
+                                    SynExpr.applyFunction (SynExpr.createIdent "Ok") (SynExpr.CreateConst ())
+                                ]
+                                |> SynExpr.sequential
+
                             [
-                                SynExpr.createIdent "key"
+                                SynMatchClause.create
-                                SynExpr.applyFunction
+                                    (SynPat.nameWithArgs "Some" [ SynPat.named "x" ])
-                                    (SynExpr.applyFunction
+                                    (SynExpr.sequential
-                                        (SynExpr.createIdent "sprintf")
+                                        [
-                                        (SynExpr.CreateConst "--%s"))
+                                            multipleErrorMessage
-                                    argForm
+                                            |> SynExpr.pipeThroughFunction (
-                                SynExpr.createLongIdent [ "System" ; "StringComparison" ; "OrdinalIgnoreCase" ]
+                                                SynExpr.dotGet "Add" (SynExpr.createIdent' argParseErrors)
-                            ]))
+                                            )
-                    finalBranch
+                                            SynExpr.applyFunction (SynExpr.createIdent "Ok") (SynExpr.CreateConst ())
+                                        ])
+                                SynMatchClause.create
+                                    (SynPat.named "None")
+                                    (SynExpr.pipeThroughTryWith
+                                        SynPat.anon
+                                        (SynExpr.createLongIdent [ "exc" ; "Message" ]
+                                         |> SynExpr.pipeThroughFunction (SynExpr.createIdent "Some")
+                                         |> SynExpr.pipeThroughFunction (SynExpr.createIdent "Error"))
+                                        performNegatedAssignment)
+                            ]
+                            |> SynExpr.createMatch (SynExpr.createIdent' parseFn.TargetVariable)
+                        | Accumulation.List Accumulation.Required ->
+                            [
+                                SynExpr.createIdent "value"
+                                |> SynExpr.pipeThroughFunction negatedParser
+                                |> SynExpr.pipeThroughFunction (
+                                    SynExpr.createLongIdent' [ parseFn.TargetVariable ; Ident.create "Add" ]
+                                )
+                                SynExpr.CreateConst () |> SynExpr.pipeThroughFunction (SynExpr.createIdent "Ok")
+                            ]
+                            |> SynExpr.sequential
+                        | _ ->
+                            failwith
+                                "WoofWare.Myriad invariant violated: unexpected accumulation type for negated arg"
+
+                    // Match --no-argForm
+                    negatedArg
+                    |> SynExpr.ifThenElse
+                        (SynExpr.applyFunction
+                            (SynExpr.createLongIdent [ "System" ; "String" ; "Equals" ])
+                            (SynExpr.tuple
+                                [
+                                    SynExpr.createIdent "key"
+                                    SynExpr.applyFunction
+                                        (SynExpr.applyFunction
+                                            (SynExpr.createIdent "sprintf")
+                                            (SynExpr.CreateConst "--no-%s"))
+                                        argForm
+                                    SynExpr.createLongIdent [ "System" ; "StringComparison" ; "OrdinalIgnoreCase" ]
+                                ]))
+                        standardMatch
+                | Some _ -> standardMatch
             )
         )
         |> SynBinding.basic
@@ -909,6 +1142,34 @@ module internal ArgParserGenerator =
             |> PreXmlDoc.create'
         )
 
+    /// Try to extract a constant bool value from a SynExpr.
+    /// Returns Some true/false if the expr is a constant bool, None otherwise.
+    let private tryGetConstBool (expr : SynExpr) : bool option =
+        match expr |> SynExpr.stripOptionalParen with
+        | SynExpr.Const (SynConst.Bool v, _) -> Some v
+        | _ -> None
+
+    /// Helper to get the "false" case for a boolean/flag field.
+    /// For booleans: `false`
+    /// For flag DUs: the case marked with [<ArgumentFlag false>]
+    let private getFalseCase (flag : ParseFunction<'a>) : SynExpr =
+        match flag.BoolCases with
+        | None -> failwith $"LOGIC ERROR: getFalseCase called on non-boolean field %s{flag.FieldName.idText}"
+        | Some (Choice2Of2 ()) ->
+            // Boolean: return false
+            SynExpr.CreateConst false
+        | Some (Choice1Of2 flagDu) ->
+            // Flag DU: return the case associated with false
+            // Check which case has false as its arg
+            match tryGetConstBool flagDu.Case1Arg, tryGetConstBool flagDu.Case2Arg with
+            | Some false, _ -> SynExpr.createLongIdent' [ flagDu.Name ; flagDu.Case1Name ]
+            | _, Some false -> SynExpr.createLongIdent' [ flagDu.Name ; flagDu.Case2Name ]
+            | Some true, _ -> SynExpr.createLongIdent' [ flagDu.Name ; flagDu.Case2Name ]
+            | _, Some true -> SynExpr.createLongIdent' [ flagDu.Name ; flagDu.Case1Name ]
+            | None, None ->
+                // Can't determine at compile time, use FlagDu.FromBoolean with false
+                FlagDu.FromBoolean flagDu (SynExpr.CreateConst false)
+
     /// `let setFlagValue (key : string) : bool = ...`
     /// The second member of the `flags` list tuple is the constant "true" with which we will interpret the
     /// arity-0 `--foo`. So in the case of a boolean-typed field, this is `true`; in the case of a Flag-typed field,
@@ -949,21 +1210,72 @@ module internal ArgParserGenerator =
 
             (finalExpr, flag.ArgForm)
             ||> List.fold (fun finalExpr argForm ->
-                SynExpr.ifThenElse
+                // Standard match: --argForm sets to trueCase
-                    (SynExpr.applyFunction
+                let standardMatch =
-                        (SynExpr.createLongIdent [ "System" ; "String" ; "Equals" ])
+                    SynExpr.ifThenElse
-                        (SynExpr.tuple
+                        (SynExpr.applyFunction
-                            [
+                            (SynExpr.createLongIdent [ "System" ; "String" ; "Equals" ])
-                                SynExpr.createIdent "key"
+                            (SynExpr.tuple
-                                SynExpr.applyFunction
+                                [
-                                    (SynExpr.applyFunction
+                                    SynExpr.createIdent "key"
-                                        (SynExpr.createIdent "sprintf")
+                                    SynExpr.applyFunction
-                                        (SynExpr.CreateConst "--%s"))
+                                        (SynExpr.applyFunction
-                                    argForm
+                                            (SynExpr.createIdent "sprintf")
-                                SynExpr.createLongIdent [ "System" ; "StringComparison" ; "OrdinalIgnoreCase" ]
+                                            (SynExpr.CreateConst "--%s"))
-                            ]))
+                                        argForm
-                    finalExpr
+                                    SynExpr.createLongIdent [ "System" ; "StringComparison" ; "OrdinalIgnoreCase" ]
-                    matchFlag
+                                ]))
+                        finalExpr
+                        matchFlag
+
+                // If this flag accepts negation, also match --no-argForm sets to falseCase
+                if flag.AcceptsNegation then
+                    let falseCase = getFalseCase flag
+
+                    let matchNegatedFlag =
+                        [
+                            SynMatchClause.create
+                                (SynPat.nameWithArgs "Some" [ SynPat.named "x" ])
+                                // This is an error, but it's one we can gracefully report at the end.
+                                (SynExpr.sequential
+                                    [
+                                        multipleErrorMessage
+                                        |> SynExpr.pipeThroughFunction (
+                                            SynExpr.dotGet "Add" (SynExpr.createIdent' argParseErrors)
+                                        )
+                                        SynExpr.CreateConst true
+                                    ])
+
+                            SynMatchClause.create
+                                (SynPat.named "None")
+                                ([
+                                    SynExpr.assign
+                                        (SynLongIdent.createI flag.TargetVariable)
+                                        (SynExpr.pipeThroughFunction (SynExpr.createIdent "Some") falseCase)
+                                    SynExpr.CreateConst true
+                                 ]
+                                 |> SynExpr.sequential)
+                        ]
+                        |> SynExpr.createMatch (SynExpr.createIdent' flag.TargetVariable)
+
+                    // Match --no-argForm
+                    SynExpr.ifThenElse
+                        (SynExpr.applyFunction
+                            (SynExpr.createLongIdent [ "System" ; "String" ; "Equals" ])
+                            (SynExpr.tuple
+                                [
+                                    SynExpr.createIdent "key"
+                                    SynExpr.applyFunction
+                                        (SynExpr.applyFunction
+                                            (SynExpr.createIdent "sprintf")
+                                            (SynExpr.CreateConst "--no-%s"))
+                                        argForm
+                                    SynExpr.createLongIdent [ "System" ; "StringComparison" ; "OrdinalIgnoreCase" ]
+                                ]))
+                        standardMatch
+                        matchNegatedFlag
+                else
+                    standardMatch
             )
         )
         |> SynBinding.basic [ Ident.create "setFlagValue" ] [ SynPat.annotateType SynType.string (SynPat.named "key") ]
@@ -1261,6 +1573,7 @@ module internal ArgParserGenerator =
 
     /// Takes a single argument, `args : string list`, and returns something of the type indicated by `recordType`.
     let createRecordParse
+        (typeHelpText : SynExpr option)
         (parseState : Ident)
         (flagDus : FlagDu list)
         (ambientRecords : RecordType list)
@@ -1327,7 +1640,7 @@ module internal ArgParserGenerator =
             |> SynExpr.applyTo (SynExpr.CreateConst ())
             |> SynBinding.basic [ argParseErrors ] []
 
-        let helpText = helpText recordType.Name pos nonPos
+        let helpText = helpText typeHelpText recordType.Name pos nonPos
 
         let bindings = errorCollection :: helpText :: bindings
 
@@ -1624,14 +1937,25 @@ module internal ArgParserGenerator =
                 | _ -> None
             )
 
-        let taggedType =
+        let taggedType, typeHelpText =
             match taggedType with
-            | SynTypeDefn.SynTypeDefn (sci,
+            | SynTypeDefn.SynTypeDefn (SynComponentInfo.SynComponentInfo (attributes = attrs) as sci,
                                        SynTypeDefnRepr.Simple (SynTypeDefnSimpleRepr.Record (access, fields, _), _),
                                        smd,
                                        _,
                                        _,
-                                       _) -> RecordType.OfRecord sci smd access fields
+                                       _) ->
+                let typeHelp =
+                    attrs
+                    |> SynAttributes.toAttrs
+                    |> List.tryPick (fun a ->
+                        match (List.last a.TypeName.LongIdent).idText with
+                        | "ArgumentHelpTextAttribute"
+                        | "ArgumentHelpText" -> Some a.ArgExpr
+                        | _ -> None
+                    )
+
+                RecordType.OfRecord sci smd access fields, typeHelp
             | _ -> failwith "[<ArgParser>] currently only supports being placed on records."
 
         let modAttrs, modName =
@@ -1689,7 +2013,7 @@ module internal ArgParserGenerator =
                 |> SynPat.annotateType (SynType.appPostfix "list" SynType.string)
 
             let parsePrime =
-                createRecordParse parseStateIdent flagDus allRecordTypes taggedType
+                createRecordParse typeHelpText parseStateIdent flagDus allRecordTypes taggedType
                 |> SynBinding.basic
                     [ Ident.create "parse'" ]
                     [

WoofWare.Myriad.Plugins/CapturingInterfaceMockGenerator.fs

@@ -19,7 +19,9 @@ module internal CapturingInterfaceMockGenerator =
     open Fantomas.FCS.Text.Range
 
     [<RequireQualifiedAccess>]
-    type private KnownInheritance = | IDisposable
+    type private KnownInheritance =
+        | IDisposable
+        | IAsyncDisposable
 
     /// Expects the input `args` list to have more than one element.
     let private createTypeForArgs
@@ -209,6 +211,8 @@ module internal CapturingInterfaceMockGenerator =
                     | [] -> failwith "Unexpected empty identifier in inheritance declaration"
                     | [ "IDisposable" ]
                     | [ "System" ; "IDisposable" ] -> KnownInheritance.IDisposable
+                    | [ "IAsyncDisposable" ]
+                    | [ "System" ; "IAsyncDisposable" ] -> KnownInheritance.IAsyncDisposable
                     | _ -> failwithf $"Unrecognised inheritance identifier: %+A{name}"
                 | x -> failwithf $"Unrecognised type in inheritance: %+A{x}"
             )
@@ -250,12 +254,26 @@ module internal CapturingInterfaceMockGenerator =
 
         let emptyRecordFieldInstantiations =
             let interfaceExtras =
-                if inherits.Contains KnownInheritance.IDisposable then
+                let disposable =
-                    let unitFun = SynExpr.createThunk (SynExpr.CreateConst ())
+                    if inherits.Contains KnownInheritance.IDisposable then
+                        let unitFun = SynExpr.createThunk (SynExpr.CreateConst ())
+                        [ SynLongIdent.createS "Dispose", unitFun ]
+                    else
+                        []
 
-                    [ SynLongIdent.createS "Dispose", unitFun ]
+                let asyncDisposable =
-                else
+                    if inherits.Contains KnownInheritance.IAsyncDisposable then
-                    []
+                        let valueTaskCtor =
+                            SynExpr.createLongIdent [ "System" ; "Threading" ; "Tasks" ; "ValueTask" ]
+                            |> SynExpr.applyTo (SynExpr.CreateConst ())
+                            |> SynExpr.paren
+                            |> SynExpr.createLambda "()"
+
+                        [ SynLongIdent.createS "DisposeAsync", valueTaskCtor ]
+                    else
+                        []
+
+                disposable @ asyncDisposable
 
             let originalMembers =
                 fields
@@ -275,23 +293,42 @@ module internal CapturingInterfaceMockGenerator =
                 [ Ident.create "Empty" ]
                 [ SynPat.unit ]
                 (SynExpr.createRecord None emptyRecordFieldInstantiations)
-            |> SynBinding.withXmlDoc (PreXmlDoc.create "An implementation where every non-unit method throws.")
+            |> SynBinding.withXmlDoc (PreXmlDoc.create "An implementation where every non-disposal method throws.")
             |> SynBinding.withReturnAnnotation constructorReturnType
             |> SynMemberDefn.staticMember
 
         let recordFields =
             let extras =
-                if inherits.Contains KnownInheritance.IDisposable then
+                let disposable =
-                    {
+                    if inherits.Contains KnownInheritance.IDisposable then
-                        Attrs = []
+                        {
-                        Ident = Some (Ident.create "Dispose")
+                            Attrs = []
-                        Type = SynType.funFromDomain SynType.unit SynType.unit
+                            Ident = Some (Ident.create "Dispose")
-                    }
+                            Type = SynType.funFromDomain SynType.unit SynType.unit
-                    |> SynField.make
+                        }
-                    |> SynField.withDocString (PreXmlDoc.create "Implementation of IDisposable.Dispose")
+                        |> SynField.make
-                    |> List.singleton
+                        |> SynField.withDocString (PreXmlDoc.create "Implementation of IDisposable.Dispose")
-                else
+                        |> List.singleton
-                    []
+                    else
+                        []
+
+                let asyncDisposable =
+                    if inherits.Contains KnownInheritance.IAsyncDisposable then
+                        {
+                            Attrs = []
+                            Ident = Some (Ident.create "DisposeAsync")
+                            Type =
+                                SynType.funFromDomain
+                                    SynType.unit
+                                    (SynType.createLongIdent' [ "System" ; "Threading" ; "Tasks" ; "ValueTask" ])
+                        }
+                        |> SynField.make
+                        |> SynField.withDocString (PreXmlDoc.create "Implementation of IAsyncDisposable.DisposeAsync")
+                        |> List.singleton
+                    else
+                        []
+
+                disposable @ asyncDisposable
 
             let nonExtras =
                 fields |> Map.toSeq |> Seq.map (fun (_, (field, _)) -> field) |> Seq.toList
@@ -528,6 +565,23 @@ module internal CapturingInterfaceMockGenerator =
                         Some [ mem ],
                         range0
                     )
+
+                | KnownInheritance.IAsyncDisposable ->
+                    let mem =
+                        SynExpr.createLongIdent [ "this" ; "DisposeAsync" ]
+                        |> SynExpr.applyTo (SynExpr.CreateConst ())
+                        |> SynBinding.basic [ Ident.create "this" ; Ident.create "DisposeAsync" ] [ SynPat.unit ]
+                        |> SynBinding.withReturnAnnotation (
+                            SynType.createLongIdent' [ "System" ; "Threading" ; "Tasks" ; "ValueTask" ]
+                        )
+                        |> SynMemberDefn.memberImplementation
+
+                    SynMemberDefn.Interface (
+                        SynType.createLongIdent' [ "System" ; "IAsyncDisposable" ],
+                        Some range0,
+                        Some [ mem ],
+                        range0
+                    )
             )
             |> Seq.toList
 

WoofWare.Myriad.Plugins/CataGenerator.fs

@@ -1209,6 +1209,10 @@ type CreateCatamorphismGenerator () =
         member _.ValidInputExtensions = [ ".fs" ]
 
         member _.Generate (context : GeneratorContext) =
+            let targetedTypes =
+                MyriadParamParser.render context.AdditionalParameters
+                |> Map.map (fun _ v -> v.Split '!' |> Array.toList |> List.map DesiredGenerator.Parse)
+
             let ast, _ =
                 Ast.fromFilename context.InputFilename |> Async.RunSynchronously |> Array.head
 
@@ -1218,17 +1222,26 @@ type CreateCatamorphismGenerator () =
 
             let namespaceAndTypes =
                 types
-                |> List.choose (fun (ns, types) ->
+                |> List.collect (fun (ns, types) ->
-                    let typeWithAttr =
+                    types
-                        types
+                    |> List.choose (fun typeDef ->
-                        |> List.tryPick (fun ty ->
+                        match SynTypeDefn.getAttribute typeof<CreateCatamorphismAttribute>.Name typeDef with
-                            match SynTypeDefn.getAttribute typeof<CreateCatamorphismAttribute>.Name ty with
+                        | None ->
-                            | None -> None
+                            let name = SynTypeDefn.getName typeDef |> List.map _.idText |> String.concat "."
-                            | Some attr -> Some (attr.ArgExpr, ty)
-                        )
 
-                    match typeWithAttr with
+                            match Map.tryFind name targetedTypes with
-                    | Some taggedType ->
+                            | Some desired ->
+                                desired
+                                |> List.tryPick (fun generator ->
+                                    match generator with
+                                    | DesiredGenerator.CreateCatamorphism cataOutputName ->
+                                        Some (SynExpr.CreateConst cataOutputName, typeDef)
+                                    | _ -> None
+                                )
+                            | None -> None
+                        | Some attr -> Some (attr.ArgExpr, typeDef)
+                    )
+                    |> List.map (fun (typeName, taggedType) ->
                         let unions, records, others =
                             (([], [], []), types)
                             ||> List.fold (fun
@@ -1246,8 +1259,8 @@ type CreateCatamorphismGenerator () =
                             failwith
                                 $"Error: all types recursively defined together with a CreateCatamorphism type must be discriminated unions or records. %+A{others}"
 
-                        Some (ns, taggedType, unions, records)
+                        (ns, (typeName, taggedType), unions, records)
-                    | _ -> None
+                    )
                 )
 
             let modules =

WoofWare.Myriad.Plugins/InterfaceMockGenerator.fs

@@ -20,7 +20,9 @@ module internal InterfaceMockGenerator =
         | Some id -> id
 
     [<RequireQualifiedAccess>]
-    type private KnownInheritance = | IDisposable
+    type private KnownInheritance =
+        | IDisposable
+        | IAsyncDisposable
 
     let createType
         (spec : GenerateMockOutputSpec)
@@ -39,6 +41,8 @@ module internal InterfaceMockGenerator =
                     | [] -> failwith "Unexpected empty identifier in inheritance declaration"
                     | [ "IDisposable" ]
                     | [ "System" ; "IDisposable" ] -> KnownInheritance.IDisposable
+                    | [ "IAsyncDisposable" ]
+                    | [ "System" ; "IAsyncDisposable" ] -> KnownInheritance.IAsyncDisposable
                     | _ -> failwithf "Unrecognised inheritance identifier: %+A" name
                 | x -> failwithf "Unrecognised type in inheritance: %+A" x
             )
@@ -69,12 +73,26 @@ module internal InterfaceMockGenerator =
 
         let constructorFields =
             let extras =
-                if inherits.Contains KnownInheritance.IDisposable then
+                let disposable =
-                    let unitFun = SynExpr.createThunk (SynExpr.CreateConst ())
+                    if inherits.Contains KnownInheritance.IDisposable then
+                        let unitFun = SynExpr.createThunk (SynExpr.CreateConst ())
+                        [ SynLongIdent.createS "Dispose", unitFun ]
+                    else
+                        []
 
-                    [ SynLongIdent.createS "Dispose", unitFun ]
+                let asyncDisposable =
-                else
+                    if inherits.Contains KnownInheritance.IAsyncDisposable then
-                    []
+                        let valueTaskCtor =
+                            SynExpr.createLongIdent [ "System" ; "Threading" ; "Tasks" ; "ValueTask" ]
+                            |> SynExpr.applyTo (SynExpr.CreateConst ())
+                            |> SynExpr.paren
+                            |> SynExpr.createLambda "()"
+
+                        [ SynLongIdent.createS "DisposeAsync", valueTaskCtor ]
+                    else
+                        []
+
+                disposable @ asyncDisposable
 
             let nonExtras =
                 fields
@@ -90,23 +108,42 @@ module internal InterfaceMockGenerator =
                  else
                      [ SynPat.unit ])
                 (SynExpr.createRecord None constructorFields)
-            |> SynBinding.withXmlDoc (PreXmlDoc.create "An implementation where every method throws.")
+            |> SynBinding.withXmlDoc (PreXmlDoc.create "An implementation where every non-disposal method throws.")
             |> SynBinding.withReturnAnnotation constructorReturnType
             |> SynMemberDefn.staticMember
 
         let fields =
             let extras =
-                if inherits.Contains KnownInheritance.IDisposable then
+                let disposable =
-                    {
+                    if inherits.Contains KnownInheritance.IDisposable then
-                        Attrs = []
+                        {
-                        Ident = Some (Ident.create "Dispose")
+                            Attrs = []
-                        Type = SynType.funFromDomain SynType.unit SynType.unit
+                            Ident = Some (Ident.create "Dispose")
-                    }
+                            Type = SynType.funFromDomain SynType.unit SynType.unit
-                    |> SynField.make
+                        }
-                    |> SynField.withDocString (PreXmlDoc.create "Implementation of IDisposable.Dispose")
+                        |> SynField.make
-                    |> List.singleton
+                        |> SynField.withDocString (PreXmlDoc.create "Implementation of IDisposable.Dispose")
-                else
+                        |> List.singleton
-                    []
+                    else
+                        []
+
+                let asyncDisposable =
+                    if inherits.Contains KnownInheritance.IAsyncDisposable then
+                        {
+                            Attrs = []
+                            Ident = Some (Ident.create "DisposeAsync")
+                            Type =
+                                SynType.funFromDomain
+                                    SynType.unit
+                                    (SynType.createLongIdent' [ "System" ; "Threading" ; "Tasks" ; "ValueTask" ])
+                        }
+                        |> SynField.make
+                        |> SynField.withDocString (PreXmlDoc.create "Implementation of IAsyncDisposable.DisposeAsync")
+                        |> List.singleton
+                    else
+                        []
+
+                disposable @ asyncDisposable
 
             extras @ fields
 
@@ -212,6 +249,23 @@ module internal InterfaceMockGenerator =
                         Some [ mem ],
                         range0
                     )
+
+                | KnownInheritance.IAsyncDisposable ->
+                    let mem =
+                        SynExpr.createLongIdent [ "this" ; "DisposeAsync" ]
+                        |> SynExpr.applyTo (SynExpr.CreateConst ())
+                        |> SynBinding.basic [ Ident.create "this" ; Ident.create "DisposeAsync" ] [ SynPat.unit ]
+                        |> SynBinding.withReturnAnnotation (
+                            SynType.createLongIdent' [ "System" ; "Threading" ; "Tasks" ; "ValueTask" ]
+                        )
+                        |> SynMemberDefn.memberImplementation
+
+                    SynMemberDefn.Interface (
+                        SynType.createLongIdent' [ "System" ; "IAsyncDisposable" ],
+                        Some range0,
+                        Some [ mem ],
+                        range0
+                    )
             )
             |> Seq.toList
 

WoofWare.Myriad.Plugins/Parameters.fs

@@ -1,11 +1,14 @@
 namespace WoofWare.Myriad.Plugins
 
+open System
+
 type internal DesiredGenerator =
     | InterfaceMock of isInternal : bool option
     | CapturingInterfaceMock of isInternal : bool option
     | JsonParse of extensionMethod : bool option
     | JsonSerialize of extensionMethod : bool option
     | HttpClient of extensionMethod : bool option
+    | CreateCatamorphism of typeName : string
 
     static member Parse (s : string) =
         match s with
@@ -24,4 +27,10 @@ type internal DesiredGenerator =
         | "HttpClient" -> DesiredGenerator.HttpClient None
         | "HttpClient(true)" -> DesiredGenerator.HttpClient (Some true)
         | "HttpClient(false)" -> DesiredGenerator.HttpClient (Some false)
-        | _ -> failwith $"Failed to parse as a generator specification: %s{s}"
+        | _ ->
+            let prefix = "CreateCatamorphism("
+
+            if s.StartsWith (prefix, StringComparison.Ordinal) && s.EndsWith ')' then
+                DesiredGenerator.CreateCatamorphism (s.Substring (prefix.Length, s.Length - prefix.Length - 1))
+            else
+                failwith $"Failed to parse as a generator specification: %s{s}"

WoofWare.Myriad.Plugins/version.json

@@ -1,5 +1,5 @@
 {
-  "version": "9.0",
+  "version": "9.1",
   "publicReleaseRefSpec": [
     "^refs/heads/main$"
   ],

analyzers/analyzers.fsproj

@@ -10,8 +10,8 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageDownload Include="WoofWare.FSharpAnalyzers" Version="[0.2.1]" />
+    <PackageDownload Include="WoofWare.FSharpAnalyzers" Version="[0.2.2]" />
-    <PackageDownload Include="G-Research.FSharp.Analyzers" Version="[0.19.0]" />
+    <PackageDownload Include="G-Research.FSharp.Analyzers" Version="[0.20.0]" />
   </ItemGroup>
 
 </Project>

flake.lock

@@ -20,11 +20,11 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1762361079,
+        "lastModified": 1764138170,
-        "narHash": "sha256-lz718rr1BDpZBYk7+G8cE6wee3PiBUpn8aomG/vLLiY=",
+        "narHash": "sha256-2bCmfCUZyi2yj9FFXYKwsDiaZmizN75cLhI/eWmf3tk=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "ffcdcf99d65c61956d882df249a9be53e5902ea5",
+        "rev": "bb813de6d2241bcb1b5af2d3059f560c66329967",
         "type": "github"
       },
       "original": {

nix/deps.json

@@ -1,8 +1,8 @@
 [
   {
     "pname": "ApiSurface",
-    "version": "5.0.2",
+    "version": "5.0.3",
-    "hash": "sha256-zcq1H1ccQzsZQf4kolzoOBSbyz07skihgPAvQ9Jri+E="
+    "hash": "sha256-uU5mqLL6zMt17oPYMzhB57ryYC6O6FzSjmdTFg7LvNo="
   },
   {
     "pname": "fantomas",
@@ -31,8 +31,8 @@
   },
   {
     "pname": "fsharp-analyzers",
-    "version": "0.33.1",
+    "version": "0.34.1",
-    "hash": "sha256-vYXvqnf3en487svFv3CmNl24SolwMYzu6zKKGXNxSu8="
+    "hash": "sha256-Y6PzfVGob2EgX29ZhZIde5EhiZ28Y1+U2pJ6ybIsHV0="
   },
   {
     "pname": "FSharp.Core",
@@ -91,13 +91,13 @@
   },
   {
     "pname": "Microsoft.CodeCoverage",
-    "version": "18.0.0",
+    "version": "18.0.1",
-    "hash": "sha256-1RNxheCYASMusDC48BXtaO3MhnInw15JVfjfLM1VMGA="
+    "hash": "sha256-G6y5iyHZ3R2shlLCW/uTusio/UqcnWT79X+UAbxvDQY="
   },
   {
     "pname": "Microsoft.NET.Test.Sdk",
-    "version": "18.0.0",
+    "version": "18.0.1",
-    "hash": "sha256-9iW+9mvMeZgDXwSoR08bnvRNsN4jT8OVWcjq3lcE+cs="
+    "hash": "sha256-0c3/rp9di0w7E5UmfRh6Prrm3Aeyi8NOj5bm2i6jAh0="
   },
   {
     "pname": "Microsoft.NETCore.App.Host.linux-arm64",
@@ -201,13 +201,13 @@
   },
   {
     "pname": "Microsoft.TestPlatform.ObjectModel",
-    "version": "18.0.0",
+    "version": "18.0.1",
-    "hash": "sha256-O/ivHdoIO+q1n0byJ9OZO4quOqACOD3K3Qm00wfhuZk="
+    "hash": "sha256-oJbS7SZ46RzyOQ+gCysW7qJRy7V8RlQVa5d8uajb91M="
   },
   {
     "pname": "Microsoft.TestPlatform.TestHost",
-    "version": "18.0.0",
+    "version": "18.0.1",
-    "hash": "sha256-qAIX2Rqxrnh1xaYRjCbkkvvMm407oyKihqyVjURX5wY="
+    "hash": "sha256-OXYf5vg4piDr10ve0bZ2ZSb+nb3yOiHayJV3cu5sMV4="
   },
   {
     "pname": "Myriad.Core",
@@ -386,8 +386,13 @@
   },
   {
     "pname": "WoofWare.Expect",
-    "version": "0.8.4",
+    "version": "0.8.5",
-    "hash": "sha256-UI7f2nt4g4Gg1Ke/IChrA4fpVOYAChXpvR6zkKfkmzE="
+    "hash": "sha256-rMlkk1osadQYwxmb0KAHqsB51hinTf7NzI0zyovpx04="
+  },
+  {
+    "pname": "WoofWare.NUnitTestRunner",
+    "version": "0.3.9",
+    "hash": "sha256-+QVx5NYdY1JZoMcWfJRwFgvEj2dBxWlJU0mu1Hmnlhs="
   },
   {
     "pname": "WoofWare.Whippet.Fantomas",