[Fable-Python] import statement falsely changed to snake_case.

[Freymaurer]

The minimal reproduction example requires two files:

Setup

// TestImport.fsx

#r "nuget: Fable.Core, 4.3.0"

open Fable.Core

type FlowchartDirection = 
    | TB
    | TD

[<AttachMembers>]
type flowchartDirection =
    static member tb = FlowchartDirection.TB
    static member td = FlowchartDirection.TD

// test.fsx

#r "nuget: Fable.Core, 4.3.0"
#load "./TestImport.fsx"

open TestImport

printfn "Hello World: %A" flowchartDirection.tb

Transpiled Files

Transpile with dotnet fable .\test.fsx --lang py. I used fable version 4.16.0

# test_import.py
#...
class flowchartDirection:
    @staticmethod
    def tb() -> FlowchartDirection:
        return FlowchartDirection(0)

    @staticmethod
    def td() -> FlowchartDirection:
        return FlowchartDirection(1)
#...

# test.py
from __future__ import annotations
from fable_modules.fable_library.string_ import (to_console, printf)
from test_import import (flowchart_direction, FlowchartDirection)

arg: FlowchartDirection = flowchart_direction.bt()

to_console(printf("Hello World: %A"))(arg)

Problem

In test_import.py we can still find "flowchartDirection", but the import statement in test.py was falsely changed to snake_case.

Personally i would favor having the import be the correct name, and keep the name as written. I hope this helps finding the underlying issue.

[dbrattli]

I've added a fix for this (#3811), but the class will be translated to snake case i.e flowchart_direction. This is because we currently snake_case everything that do not start with a capital letter. So you will need to CapWords the class name to avoid snake casing. Either rename it to Flowchartdirection or use a module instead so you can use the same name as the union e.g:

namespace TestImport

open Fable.Core

type FlowchartDirection =
    | TB
    | TD

module FlowchartDirection =
    let tb = FlowchartDirection.TB
    let td = FlowchartDirection.TD

[Freymaurer]

as long as the import works correctly its fine with me 🙂

[Freymaurer]

One more follow up note:

this reflection function still contains the camel case name:

Not sure for what it is uses, just wanted to mention it @dbrattli

[Freymaurer]

ah damn one more thing, and this is breaking:

Here you can see f# code in which i use a static member of stateDiagram.

in transpiled python (fable v.4.17.0) state_diagram is correct snake_case, but the reference in the members is still stateDiagram:

EDIT: Using the following workaround i used before your update, still makes it transpile correctly:

#if FABLE_COMPILER_PYTHON
[<CompiledName("state_diagram")>]
#endif
[<AttachMembers>]
type stateDiagram =

..transpiles to:

@dbrattli

[dbrattli]

Have added fixes for this. Please reopen or post new issues if you find new problems