Fable

Spec sheet

What it does

Fable is a compiler that lets developers use F# to build applications.Read 9 Oct 2026 · fable.io

Audience

The documentation describes Fable as a way to build applications with F#, including browser UIs, and provides guidance for .NET and JavaScript developers.Read 9 Oct 2026 · fable.io

Support

The project repository accepts bug reports and feature requests, and notes that maintainers do not check its Gitter chat regularly.Read 9 Oct 2026 · github.com

License

The Fable repository identifies its license as MIT.Read 9 Oct 2026 · github.com

Beam requirement

The Beam setup guide requires Erlang/OTP 25 or higher and rebar3.Read 4 Oct 2026 · fable.io

Build integrations

For JavaScript projects, Fable integrates with bundlers including Vite, Parcel, and Webpack.Read 9 Oct 2026 · fable.io

Build workflow

The CLI supports release, watch, and clean commands, plus options such as output directory and source maps.Read 4 Oct 2026 · fable.io

Compatibility limit

Not all NuGet packages work with Fable; the documentation advises checking whether each library is Fable-compatible.Read 9 Oct 2026 · fable.io

Dependencies

Fable uses NuGet to load F# libraries, while JavaScript dependencies are listed in package.json.Read 9 Oct 2026 · fable.io

Editor support

The official site names Visual Studio Code and JetBrains Rider among the editors usable with Fable.Read 9 Oct 2026 · fable.io

JavaScript interop

Fable supports importing JavaScript modules and using NPM packages from F# code.Read 4 Oct 2026 · fable.io

JavaScript output

Fable transpiles F# to ES2015 JavaScript.Read 9 Oct 2026 · fable.io

Language features

The site highlights F# features including immutability by default, pattern matching, units of measure, and type providers.Read 9 Oct 2026 · fable.io

Libraries

The documentation lists Fable.Core, Fable.Browser.Dom, Fable.Elmish.React, and Thoth.Json as libraries available for Fable projects, and cautions that not all NuGet libraries work with Fable.Read 4 Oct 2026 · fable.io

Online access

The homepage links to an online Fable REPL.Read 4 Oct 2026 · fable.io

Other targets

Dart and Python are listed as beta, Rust as alpha, and PHP and Beam (Erlang) as experimental.Read 4 Oct 2026 · fable.io

Output targets

Fable lists JavaScript and TypeScript as stable targets, Dart and Python as beta, Rust as alpha, and PHP and Beam (Erlang) as experimental.Read 9 Oct 2026 · fable.io

Project setup

The getting started guide installs Fable as a .NET tool and adds Fable.Core to an F# project.Read 4 Oct 2026 · fable.io

Python requirement

Fable Python targets Python 3.12 or higher; Python 3.10 and 3.11 are deprecated.Read 4 Oct 2026 · fable.io

Stable targets

JavaScript and TypeScript are listed as stable targets.Read 4 Oct 2026 · fable.io

Testing

The documentation says unit testing is available through Fable.Mocha and that another test runner can be used.Read 9 Oct 2026 · fable.io

Where Specifiction places it

• Code Transpilers#22 of 287.3