[Python] Revert removal of Fable.Core.Py.python

src/Fable.Cli/CHANGELOG.md

@@ -36,6 +36,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 #### Python
 
 * Added `Async.StartChild` (by @dbrattli)
+* Fix #3482: Revert removal of `Py.python` and `Py.expr_python` (by @dbrattli)
 
 ## 4.2.2 - 2023-10-14
 

src/Fable.Core/CHANGELOG.md

@@ -6,6 +6,12 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
+### Added
+
+#### Python
+
+* Fix #3482: Revert removal of `Py.python` and `Py.expr_python` (by @dbrattli)
+
 ## 4.1.0
 
 * Fix #3482: Remove `Py.python` and `Py.expr_python`

src/Fable.Core/Fable.Core.Py.fs

@@ -43,3 +43,7 @@ module Py =
     /// https://code.visualstudio.com/docs/python/jupyter-support-py
     [<Emit("# %%", isStatement=true)>]
     let NEW_CELL: unit = nativeOnly
+
+     /// Embeds literal Python code into F#. Code will be printed as statements,
+    /// if you want to return a value use Python `return` keyword within a function.
+    let python (template: string): 'T = nativeOnly

src/Fable.Transforms/Python/Replacements.fs

@@ -867,6 +867,12 @@ let fableCoreLib (com: ICompiler) (ctx: Context) r t (i: CallInfo) (thisArg: Exp
         | "typedArrays" -> makeBoolConst com.Options.TypedArrays |> Some
         | "extension" -> makeStrConst com.Options.FileExtension |> Some
         | _ -> None
+    | "Fable.Core.Py", ("python" | "expr_python" as meth) ->
+        let isStatement = meth <> "expr_python"
+        match args with
+        | RequireStringConstOrTemplate com ctx r template::_ ->
+            emitTemplate r t [] isStatement template  |> Some
+        | _ -> None
     | "Fable.Core.PyInterop", _ ->
         match i.CompiledName, args with
         | Naming.StartsWith "import" suffix, _ ->

src/fable-library-py/fable_library/async_.py

@@ -34,6 +34,7 @@
 
 
 _T = TypeVar("_T")
+_U = TypeVar("_U")
 
 
 def cancellation_token() -> Async[CancellationToken]:
@@ -110,6 +111,15 @@ def delayed() -> Async[list[_T]]:
     return delay(delayed)
 
 
+def parallel2(a: Async[_T], b: Async[_U]) -> Async[list[_T | _U]]:
+    def delayed() -> Async[list[_T, _T]]:
+        tasks: Iterable[Future[_T]] = map(start_as_task, [a, b])  # type: ignore
+        all: Future[list[_T]] = asyncio.gather(*tasks)
+        return await_task(all)
+
+    return delay(delayed)
+
+
 def sequential(computations: Iterable[Async[_T]]) -> Async[list[_T | None]]:
     def delayed() -> Async[list[_T | None]]:
         results: list[_T] = []
@@ -266,28 +276,33 @@ def cancel(_: OperationCanceledError) -> None:
     return tcs.get_task()
 
 
+def throw_after(milliseconds_due_time: int) -> Async[None]:
+    def cont(ctx: IAsyncContext[None]) -> None:
+        def cancel() -> None:
+            ctx.on_cancel(OperationCanceledError())
+
+        token_id = ctx.cancel_token.add_listener(cancel)
+
+        def timeout() -> None:
+            ctx.cancel_token.remove_listener(token_id)
+            ctx.on_error(TimeoutError())
+
+        ctx.trampoline.run_later(timeout, milliseconds_due_time / 1000.0)
+
+    return protected_cont(cont)
+
+
 def start_child(computation: Async[_T], ms: int | None = None) -> Async[Async[_T]]:
     if ms:
         computation_with_timeout = protected_bind(
-            parallel(computation, throw_after(ms)), lambda xs: protected_return(xs[0])
+            parallel2(computation, throw_after(ms)), lambda xs: protected_return(xs[0])
         )
         return start_child(computation_with_timeout)
 
     task = start_as_task(computation)
 
     def cont(ctx: IAsyncContext[Async[_T]]) -> None:
-        def on_success(_: Async[_T]) -> None:
-            ctx.on_success(await_task(task))
-
-        on_error = ctx.on_error
-        on_cancel = ctx.on_cancel
-        trampoline = ctx.trampoline
-        cancel_token = ctx.cancel_token
-
-        ctx_ = IAsyncContext.create(
-            on_success, on_error, on_cancel, trampoline, cancel_token
-        )
-        computation(ctx_)
+        protected_return(await_task(task))(ctx)
 
     return protected_cont(cont)