Fable 5.0.0-alpha.20

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/fcs folder. 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:

dotnet SDK 6 or higher
node.js with npm
Python 3 is installed and available as python
Uv
Rust
Dart

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

Added

[Python] Add Array.skipWhile support (by @dbrattli)
[Python] Add Array.takeWhile support (by @dbrattli)
[Python] Allow IEnumerator_1 as base class to fix typing issues (by @dbrattli)
[Python] Add Pythonic import path syntax for relative imports (.module, ..parent, ...grandparent) (by @dbrattli)
[Python] Add [<Py.DecorateTemplate>] attribute for creating custom decorator attributes (by @dbrattli)
[Python] Add [<Py.ClassAttributesTemplate>] attribute for creating custom class attribute shortcuts (by @dbrattli)
[Python] Add [<Py.DataClass>] as a built-in shorthand for [<Py.ClassAttributes(style = Attributes, init = false)>] (by @dbrattli)

Fixed

[Python] Fix String.Concat spread operator issue in Python transpilation (by @dbrattli)
[Python] Fix regression [<Erase>] on class types not preventing them from being emitted to Python (by @dbrattli)
[Python] Fix regression %A format specifier to output booleans as lowercase true/false (by @dbrattli)
[Python] Fix various bugs in fable-library numeric types and string operations (by @dbrattli)

Changed

[Python] [<Py.Decorate>] now emits decorator strings verbatim and adds importFrom parameter for explicit import control (by @dbrattli)

This package has no dependencies.

Version	Downloads	Last updated
5.0.0-alpha.20	1	12/15/2025
5.0.0-alpha.19	0	12/04/2025
5.0.0-alpha.18	0	12/03/2025
5.0.0-alpha.17	1	12/15/2025
5.0.0-alpha.16	0	11/25/2025
5.0.0-alpha.15	0	11/19/2025
5.0.0-alpha.14	0	07/25/2025
5.0.0-alpha.13	0	05/04/2025
5.0.0-alpha.12	0	03/14/2025
5.0.0-alpha.11	0	03/03/2025
5.0.0-alpha.10	0	02/16/2025
5.0.0-alpha.9	0	01/28/2025
5.0.0-alpha.8	0	01/27/2025
5.0.0-alpha.7	0	01/23/2025
5.0.0-alpha.6	0	01/23/2025
5.0.0-alpha.5	0	01/09/2025
5.0.0-alpha.4	0	01/03/2025
5.0.0-alpha.3	0	12/18/2024
5.0.0-alpha.2	0	11/26/2024
5.0.0-alpha.1	0	11/24/2024
4.28.0	0	11/25/2025
4.27.0	0	11/13/2025
4.25.0	0	04/26/2025
4.24.0	0	11/19/2024
4.23.0	0	10/28/2024
4.22.0	0	10/02/2024
4.21.0	0	09/19/2024
4.20.0	0	09/04/2024
4.19.3	0	06/17/2024
4.19.2	0	06/13/2024
4.19.1	0	06/13/2024
4.19.0	0	06/10/2024
4.18.0	0	05/23/2024
4.17.0	0	04/23/2024
4.16.0	0	03/20/2024
4.15.0	0	03/18/2024
4.14.0	0	03/01/2024
4.13.0	0	02/20/2024
4.12.2	0	02/13/2024
4.12.1	0	02/13/2024
4.11.0	0	01/30/2024
4.10.0	0	01/25/2024
4.9.0	0	12/14/2023
4.8.1	0	12/12/2023
4.8.0	0	12/12/2023
4.7.0	0	12/06/2023
4.6.0	0	11/27/2023
4.5.0	0	11/07/2023
4.4.1	0	10/25/2023
4.4.0	0	10/24/2023
4.3.0	0	10/18/2023
4.2.2	0	10/14/2023
4.2.1	0	09/29/2023
4.1.4	0	05/16/2023
4.1.3	0	04/28/2023
4.1.2	0	04/22/2023
4.1.1	0	04/22/2023
4.1.0	0	04/18/2023
4.1.0-beta-001	0	04/16/2023
4.0.5	0	04/08/2023
4.0.4	0	04/04/2023
4.0.3	0	03/30/2023
4.0.2	0	03/27/2023
4.0.1	0	03/18/2023
4.0.0	0	03/14/2023
4.0.0-theta-018	0	11/19/2022
4.0.0-theta-017	0	11/16/2022
4.0.0-theta-016	0	11/13/2022
4.0.0-theta-015	0	11/05/2022
4.0.0-theta-014	0	10/31/2022
4.0.0-theta-012	0	10/14/2022
4.0.0-theta-011	0	10/04/2022
4.0.0-theta-010	0	09/28/2022
4.0.0-theta-009	0	09/28/2022
4.0.0-theta-008	0	09/22/2022
4.0.0-theta-007	0	09/21/2022
4.0.0-theta-006	0	09/18/2022
4.0.0-theta-005	0	09/17/2022
4.0.0-theta-004	0	09/14/2022
4.0.0-theta-003	0	09/12/2022
4.0.0-theta-002	0	09/11/2022
4.0.0-theta-001	0	09/09/2022
4.0.0-snake-island-alpha-026	0	12/15/2025
4.0.0-snake-island-alpha-025	0	09/06/2022
4.0.0-snake-island-alpha-024	0	09/02/2022
4.0.0-snake-island-alpha-023	0	08/30/2022
4.0.0-snake-island-alpha-021	0	08/21/2022
4.0.0-snake-island-alpha-020	0	08/14/2022
4.0.0-snake-island-alpha-019	0	07/31/2022
4.0.0-snake-island-alpha-018	0	07/30/2022
4.0.0-snake-island-alpha-017	0	07/27/2022
4.0.0-snake-island-alpha-016	0	07/26/2022
4.0.0-snake-island-alpha-015	0	07/26/2022
4.0.0-snake-island-alpha-014	0	07/25/2022
4.0.0-snake-island-alpha-013	0	07/25/2022
4.0.0-snake-island-alpha-012	0	07/12/2022
4.0.0-snake-island-alpha-011	0	06/23/2022
4.0.0-snake-island-alpha-010	0	06/03/2022
4.0.0-snake-island-alpha-009	0	06/02/2022
4.0.0-snake-island-alpha-008	0	06/01/2022
4.0.0-snake-island-alpha-007	0	05/25/2022
4.0.0-snake-island-alpha-006	0	05/24/2022
4.0.0-snake-island-alpha-005	0	05/23/2022
4.0.0-snake-island-alpha-004	0	05/21/2022
4.0.0-snake-island-alpha-003	0	05/20/2022
4.0.0-snake-island-alpha-002	0	05/19/2022
4.0.0-snake-island-alpha-001	0	05/11/2022
3.7.22	0	05/11/2023
3.7.21	0	05/11/2023
3.7.20	0	09/27/2022
3.7.19	0	09/27/2022
3.7.18	0	08/16/2022
3.7.17	0	07/21/2022
3.7.16	0	07/05/2022
3.7.15	0	06/29/2022
3.7.14	0	06/14/2022
3.7.12	0	05/27/2022
3.7.11	0	05/01/2022
3.7.10	0	04/29/2022
3.7.9	0	04/01/2022
3.7.8	0	03/24/2022
3.7.7	0	03/22/2022
3.7.6	0	03/16/2022
3.7.5	0	03/01/2022
3.7.4	0	02/25/2022
3.7.3	0	02/23/2022
3.7.2	0	02/22/2022
3.7.1	0	02/17/2022
3.7.0	0	02/07/2022
3.7.0-beta-015	0	01/26/2022
3.7.0-beta-014	0	01/24/2022
3.7.0-beta-012	0	01/18/2022
3.7.0-beta-011	0	01/14/2022
3.7.0-beta-010	0	01/14/2022
3.7.0-beta-009	0	01/12/2022
3.7.0-beta-008	0	01/11/2022
3.7.0-beta-007	0	01/11/2022
3.7.0-beta-006	0	01/11/2022
3.7.0-beta-005	0	01/07/2022
3.7.0-beta-004	0	01/05/2022
3.7.0-beta-003	0	01/04/2022
3.7.0-beta-002	0	12/28/2021
3.7.0-beta-001	0	12/20/2021
3.6.3	0	12/01/2021
3.6.2	0	11/26/2021
3.6.1	0	11/23/2021
3.6.0	0	11/19/2021
3.6.0-beta-003	0	11/17/2021
3.6.0-beta-002	0	11/15/2021
3.6.0-beta-001	0	11/14/2021
3.4.10	0	11/08/2021
3.4.9	0	11/05/2021
3.4.8	0	11/04/2021
3.4.7	0	10/28/2021
3.4.6	0	10/26/2021
3.4.5	0	10/21/2021
3.4.4	0	10/20/2021
3.4.3	0	10/14/2021
3.4.2	0	10/05/2021
3.4.1	0	10/04/2021
3.4.0	0	10/01/2021
3.3.1	0	09/27/2021
3.3.0	0	09/16/2021
3.3.0-beta-002	0	08/28/2021
3.3.0-beta-001	0	08/27/2021
3.2.14	0	09/11/2021
3.2.12	0	08/26/2021
3.2.11	0	08/19/2021
3.2.10	0	08/02/2021
3.2.9	0	07/08/2021
3.2.8	0	06/26/2021
3.2.7	0	06/25/2021
3.2.6	0	06/22/2021
3.2.5	0	06/21/2021
3.2.4	0	06/16/2021
3.2.3	0	06/11/2021
3.2.2	0	06/03/2021
3.2.1	0	05/28/2021
3.2.0	0	05/28/2021
3.1.16	0	05/14/2021
3.1.15	0	04/16/2021
3.1.14	0	04/09/2021
3.1.12	0	03/23/2021
3.1.11	0	03/17/2021
3.1.10	0	03/16/2021
3.1.9	0	03/15/2021
3.1.8	0	03/15/2021
3.1.7	0	03/11/2021
3.1.6	0	03/11/2021
3.1.5	0	02/18/2021
3.1.4	0	02/12/2021
3.1.3	0	02/12/2021
3.1.2	0	01/25/2021
3.1.1	0	01/13/2021
3.1.0	0	01/11/2021
3.1.0-beta-001	0	01/08/2021
3.0.5	0	12/22/2020
3.0.4	0	12/19/2020
3.0.3	0	12/18/2020
3.0.2	0	12/16/2020
3.0.1	0	12/11/2020
3.0.0	0	12/04/2020
3.0.0-nagareyama-rc-011	0	12/02/2020
3.0.0-nagareyama-rc-010	0	11/28/2020
3.0.0-nagareyama-rc-009	0	11/25/2020
3.0.0-nagareyama-rc-008	0	11/19/2020
3.0.0-nagareyama-rc-007	0	11/15/2020
3.0.0-nagareyama-rc-006	0	11/13/2020
3.0.0-nagareyama-rc-005	0	11/12/2020
3.0.0-nagareyama-rc-004	0	11/10/2020
3.0.0-nagareyama-rc-003	0	11/09/2020
3.0.0-nagareyama-rc-002	0	11/08/2020
3.0.0-nagareyama-rc-001	0	11/07/2020
3.0.0-nagareyama-beta-005	0	10/31/2020
3.0.0-nagareyama-beta-004	0	10/27/2020
3.0.0-nagareyama-beta-003	0	10/25/2020
3.0.0-nagareyama-beta-002	0	10/23/2020
3.0.0-nagareyama-beta-001	0	10/23/2020
3.0.0-nagareyama-alpha-017	0	10/22/2020
3.0.0-nagareyama-alpha-016	0	10/22/2020
3.0.0-nagareyama-alpha-015	0	10/19/2020
3.0.0-nagareyama-alpha-014	0	10/18/2020
3.0.0-nagareyama-alpha-012	0	10/15/2020
3.0.0-nagareyama-alpha-011	0	10/15/2020
3.0.0-nagareyama-alpha-010	0	10/13/2020
3.0.0-nagareyama-alpha-009	0	10/11/2020
3.0.0-nagareyama-alpha-008	0	10/05/2020
3.0.0-nagareyama-alpha-007	0	10/02/2020
3.0.0-nagareyama-alpha-006	0	09/30/2020
3.0.0-nagareyama-alpha-005	0	09/29/2020
3.0.0-nagareyama-alpha-004	0	09/28/2020
3.0.0-nagareyama-alpha-003	0	09/14/2020
3.0.0-nagareyama-alpha-002	0	09/13/2020
3.0.0-nagareyama-alpha-001	0	09/13/2020