Imports for FSX files have wrong extension.

[MattMS]

Description

When loading a FSX script inside another, it is found and transpiled correctly, but the import statement generated uses the fsx extension instead of the correct .fs.js extension.

Repro code

Contents of a.fsx:

let a v = v + 1

Contents of main.fsx:

#load "a.fsx"
open A

let b v = a v + 1

Build with the following:

fable main.fsx --run "esbuild --bundle --outfile=main.bundle.js main.fs.js"

Output in main.fs.js (with incorrect import):

import { a } from "./a.fsx";

export function b(v) {
    return a(v) + 1;
}

ESBuild fails with the following:

No loader is configured for ".fsx" files: a.fsx

Expected and actual results

Output in main.fs.js should have the correct .fs.js extension:

import { a } from "./a.fs.js";

Related information

• Fable version: 4.11.0 (installed globally)
• Operating system: Windows 11 22H2 (22621.3007)

[MattMS]

I can see some extension handling in https://github.com/fable-compiler/Fable/blob/main/src/fable-compiler-js/src/app.fs

Within member _.MakeImportPath(path) in interface Fable.Standalone.IWriter of SourceWriter:

if path.EndsWith(".fs") then

Maybe fixed as the following:

if path.EndsWith(".fs") || path.EndsWith(".fsx") then

[MangelMaxime]

Files in fable-compiler-js is when using the fable-compiler-js NPM package it is not what most people use.

Most people consume Fable via .NET which code is located in src/Fable.CLI, src/ Fable.Compiler, src/Fable.Transforms, etc.

So I don't think the file linked will be what is needed to fix your problem.