A bit of productionising

Reactivation/Seq.fs

@@ -0,0 +1,20 @@
+namespace Reactivation
+
+[<RequireQualifiedAccess>]
+module Seq =
+
+    let minMax (s : int seq) : struct (int * int) voption =
+        use e = s.GetEnumerator ()
+        if not (e.MoveNext ()) then ValueNone else
+
+        let mutable min = e.Current
+        let mutable max = e.Current
+        while e.MoveNext () do
+            if e.Current < min then min <- e.Current
+            if e.Current > max then max <- e.Current
+        ValueSome (struct (min, max))
+
+    let rangeOrZero (s : int seq) : int =
+        match minMax s with
+        | ValueNone -> 0
+        | ValueSome (min, max) -> max - min