Fable 5.0.0-alpha.15
See the version list below for details.
dotnet tool install --global Fable --version 5.0.0-alpha.15
dotnet new tool-manifest
dotnet tool install --local Fable --version 5.0.0-alpha.15
#tool dotnet:?package=Fable&version=5.0.0-alpha.15&prerelease
nuke :add-package Fable --version 5.0.0-alpha.15
Fable: F# |> JS
Fable is an F# to JavaScript compiler powered FSharp Compiler Services, designed to make F# a first-class citizen of the JavaScript ecosystem. Check the website for more information and if you find the project useful, don't forget to give us a star!
Fable actually uses a fork of FCS with a few tweaks. Binaries are in
lib/fcsfolder. See this PR for more info.
Getting started
Check this page.
Building
Requirements
Use VSCode Dev Container
You can use VSCode Dev Container to get a preconfigured environment both with requirements and VSCode extensions.
- You need to have docker installed and running.
- Install the Dev Container extension in VSCode
- Open the project in VSCode and click on the green button in the bottom left corner.
Use your machine
Make sure the following requirements are installed in your system:
Build
Run ./build.sh or ./build.cmd to see the build options.
When using VSCode, you can also run the build tasks from the command palette (Ctrl+Shift+P) by typing Run Task and selecting the task you want to run.
We also configured several debug configurations that you can use from the debug panel (Ctrl+Shift+D). This is useful as you can attach the debugger to the Fable compiler process to check what's going on.
Contributing
Just by using Fable you're already contributing! You can help the community a lot by sharing examples and experiences in your personal (or Fable's) blog and/or by editing the Fable Resources page.
Send bug reports (ideally with minimal code to reproduce the problem) and feature requests to this GitHub repository. To interact with the community you can use the Gitter chat but please note maintainers are not checking the chat regularly.
If you are up to contribute a fix or a feature yourself, you're more than welcome! Please send first an issue or a minimal Work In Progess PR so we can discuss the implementation details in advance.
List of changelogs
| Product | Versions Compatible and additional computed target framework versions. |
|---|---|
| .NET | net8.0 is compatible. net8.0-android was computed. net8.0-browser was computed. net8.0-ios was computed. net8.0-maccatalyst was computed. net8.0-macos was computed. net8.0-tvos was computed. net8.0-windows was computed. net9.0 was computed. net9.0-android was computed. net9.0-browser was computed. net9.0-ios was computed. net9.0-maccatalyst was computed. net9.0-macos was computed. net9.0-tvos was computed. net9.0-windows was computed. net10.0 was computed. net10.0-android was computed. net10.0-browser was computed. net10.0-ios was computed. net10.0-maccatalyst was computed. net10.0-macos was computed. net10.0-tvos was computed. net10.0-windows was computed. |
This package has no dependencies.
| Version | Downloads | Last Updated |
|---|---|---|
| 5.0.0-alpha.24 | 159 | 2/13/2026 |
| 5.0.0-alpha.23 | 259 | 2/3/2026 |
| 5.0.0-alpha.22 | 1,879 | 12/26/2025 |
| 5.0.0-alpha.21 | 1,074 | 12/15/2025 |
| 5.0.0-alpha.20 | 1,006 | 12/8/2025 |
| 5.0.0-alpha.19 | 569 | 12/4/2025 |
| 5.0.0-alpha.18 | 739 | 12/3/2025 |
| 5.0.0-alpha.17 | 786 | 11/27/2025 |
| 5.0.0-alpha.16 | 195 | 11/25/2025 |
| 5.0.0-alpha.15 | 1,193 | 11/19/2025 |
| 5.0.0-alpha.14 | 6,805 | 7/25/2025 |
| 5.0.0-alpha.13 | 4,471 | 5/4/2025 |
| 5.0.0-alpha.12 | 1,509 | 3/14/2025 |
| 5.0.0-alpha.11 | 847 | 3/3/2025 |
| 5.0.0-alpha.10 | 1,219 | 2/16/2025 |
| 4.29.0 | 365 | 2/13/2026 |
| 4.28.0 | 5,441 | 11/25/2025 |
| 4.27.0 | 4,400 | 11/13/2025 |
| 4.25.0 | 15,742 | 4/26/2025 |
### Added
* [TS] Added support for `erasableSyntaxOnly` in TypeScript (by @ncave)
* [All] Added some default `System` exception implementations (by @ncave)
* [All] Added `ofOption`/`toOption`/`ofValueOption`/`toValueOption` (by @ncave)
* [Python] Added `Decorate` attribute to add Python decorators to classes (by @dbrattli)
* [Python] Added `ClassAttributes` attribute to control Python class generation (@dbrattli)
* [Python] Added support for Python 3.14 (by @dbrattli)
### Changed
* [JS/TS] Replace the deprecated `substr` method with `slice` (by @Thorium)
### Fixed
* [TS] Fix ObjectExpr tests with multiple interfaces (by @ncave)
* [TS] Fix ObjectExpr abstract base constructor type (by @ncave)
* [JS/TS] Fix #4240 Missing DateTime constructor (by @ncave)
* [PHP] Fix php import extensions (by @MangelMaxime)
* [TS] Fix #3973 Typescript imports file extension (by @ncave)
* [TS] Fix support for abstract classes and members (by @ncave)
* [TS] Fix getters, setters, indexers in interfaces (by @ncave)
* [TS] Enable typedArrays flag usage for TypeScript (by @ncave)
* [All] Fix #4221 Fable.Type union case arg names (by @ncave)
* [All] Erase Nullable Reference Types to inner type (by @ncave)
* [Python] Improve Python (e.g. Pydantic) interop (by @dbrattli)
* [JS/TS] Fix comparers for non-nullable types (by @ncave)
* [Rust] Fix curried object expression getters (by @ncave)
* [Rust] Fix compiler-generated generic args (by @ncave)
* [All] Fixed #4041 missing unit argument (by @ncave)
* [JS/TS/Python] Fixed eq comparer mangling (by @ncave)
* [All] Fix all `BitConverter` return types (by @ncave)
* [TS] Don't cast union case types to `any` (by @ncave)
* [JS/TS] Fix Dictionary.ICollection.Remove (by @ncave)
* [TS/Dart] Fixed optional parameter types (by @ncave)
* [TS] Initialize un-initialized variables (by @ncave)
* [JS/TS] Replace `Error` with `Exception` (by @ncave)
* [All] Fix MSBuildResolver to include define when restoring the project (by @MangelMaxime)