refactor(js/ts/python): use struct partial active patterns and postfix array syntax (#4569)

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Co-authored-by: Dag Brattli <dag@brattli.net>
Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: fable-repo-assist[bot] <279220273+fable-repo-assist[bot]@users.noreply.github.com>
Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

Author: 6 people

src/Fable.Transforms/BabelPrinter.fs

@@ -31,22 +31,25 @@ module PrinterExtensions =
         | ExpressionStatement(expr) -> hasSideEffects (expr)
         | _ -> true
 
+    [<return: Struct>]
     let (|UndefinedOrVoid|_|) =
         function
-        | Undefined _ -> Some()
-        | UnaryExpression(argument, "void", false, _loc) when not (hasSideEffects (argument)) -> Some()
-        | _ -> None
+        | Undefined _ -> ValueSome()
+        | UnaryExpression(argument, "void", false, _loc) when not (hasSideEffects (argument)) -> ValueSome()
+        | _ -> ValueNone
 
+    [<return: Struct>]
     let (|NullOrUndefinedOrVoid|_|) =
         function
         | Literal(NullLiteral _)
-        | UndefinedOrVoid _ -> Some()
-        | _ -> None
+        | UndefinedOrVoid _ -> ValueSome()
+        | _ -> ValueNone
 
+    [<return: Struct>]
     let (|StringConstant|_|) =
         function
-        | Literal(Literal.StringLiteral(StringLiteral(value = value))) -> Some value
-        | _ -> None
+        | Literal(Literal.StringLiteral(StringLiteral(value = value))) -> ValueSome value
+        | _ -> ValueNone
 
     type Printer with
 
@@ -233,7 +236,7 @@ module PrinterExtensions =
                 id: Identifier option,
                 isAbstract: bool option,
                 superClass: SuperClass option,
-                typeParameters: TypeParameter[],
+                typeParameters: TypeParameter array,
                 implements: TypeAnnotation array,
                 members: ClassMember array,
                 loc
@@ -278,7 +281,7 @@ module PrinterExtensions =
                 id: Identifier option,
                 parameters: Parameter array,
                 body: BlockStatement,
-                typeParameters: TypeParameter[],
+                typeParameters: TypeParameter array,
                 returnType: TypeAnnotation option,
                 loc,
                 ?isDeclaration,
@@ -1521,7 +1524,7 @@ module PrinterExtensions =
             printer.PrintOptional(bound, " extends ")
         // printer.PrintOptional(``default``)
 
-        member printer.Print(parameters: TypeParameter[]) =
+        member printer.Print(parameters: TypeParameter array) =
             if parameters.Length > 0 then
                 printer.Print("<")
                 printer.PrintCommaSeparatedArray(parameters)

src/Fable.Transforms/Python/Fable2Python.Transforms.fs

@@ -2693,6 +2693,7 @@ let transformAsArray (com: IPythonCompiler) ctx expr (info: Fable.CallInfo) : Ex
 
 /// Active pattern to detect F# `use` statements compiled as TryCatch with Dispose
 /// This helps us to transform F# `use` (i.e. TryCatch) as Python `with` statements
+[<return: Struct>]
 let (|UsePattern|_|) (body: Fable.Expr) =
     match body with
     | Fable.TryCatch(tryBody,
@@ -2707,8 +2708,8 @@ let (|UsePattern|_|) (body: Fable.Expr) =
                                                       _),
                                            _,
                                            _)),
-                     _) -> Some(disposeName, tryBody)
-    | _ -> None
+                     _) -> ValueSome(disposeName, tryBody)
+    | _ -> ValueNone
 
 let rec transformAsStatements (com: IPythonCompiler) ctx returnStrategy (expr: Fable.Expr) : Statement list =
     // printfn "transformAsStatements: %A" expr

src/Fable.Transforms/Python/Fable2Python.Util.fs

@@ -432,11 +432,12 @@ module Util =
 
     let (|TransformExpr|) (com: IPythonCompiler) ctx e : Expression * Statement list = com.TransformAsExpr(ctx, e)
 
+    [<return: Struct>]
     let (|Function|_|) =
         function
-        | Fable.Lambda(arg, body, _) -> Some([ arg ], body)
-        | Fable.Delegate(args, body, _, []) -> Some(args, body)
-        | _ -> None
+        | Fable.Lambda(arg, body, _) -> ValueSome([ arg ], body)
+        | Fable.Delegate(args, body, _, []) -> ValueSome(args, body)
+        | _ -> ValueNone
 
     let getUniqueNameInRootScope (ctx: Context) name =
         let name =
@@ -910,15 +911,16 @@ module Util =
 
 
     // Active patterns for type matching
+    [<return: Struct>]
     let (|IEnumerableOfKeyValuePair|_|) (targetType: Fable.Type, sourceExpr: Fable.Expr) =
         match targetType, sourceExpr.Type with
         | Fable.DeclaredType(ent, [ Fable.DeclaredType(kvpEnt, [ _; _ ]) ]), Fable.DeclaredType(sourceEnt, _) when
             ent.FullName = Types.ienumerableGeneric
             && kvpEnt.FullName = Types.keyValuePair
             && (sourceEnt.FullName = Types.dictionary || sourceEnt.FullName = Types.idictionary)
             ->
-            Some(kvpEnt)
-        | _ -> None
+            ValueSome(kvpEnt)
+        | _ -> ValueNone
 
     let makeFieldGet (expr: Expression) (field: string) =
         Expression.attribute (expr, Identifier field, ctx = Load), []
@@ -1104,7 +1106,7 @@ module Util =
 /// Common utilities for Python transformations
 module Helpers =
     /// Returns true if the first field type can be None in Python
-    let isOptional (fields: Fable.Ident[]) =
+    let isOptional (fields: Fable.Ident array) =
         if fields.Length < 1 then
             false
         else

src/Fable.Transforms/Python/Python.AST.fs

@@ -127,7 +127,7 @@ type Literal =
     | FloatLiteral of float
     | IntLiteral of obj
     | BoolLiteral of bool
-    | BytesLiteral of byte[]
+    | BytesLiteral of byte array
     | StringLiteral of string
     | NoneLiteral
     | TupleLiteral of Literal list