Registry / web-framework / fable-compiler-netcore

fable-compiler-netcore

library0.7.42jsnpmunverified

Fable is an F# to JavaScript compiler that leverages the F# compiler service and Babel to emit clean, readable JavaScript. It compiles F# source code directly (no .NET bytecode), includes a minimal runtime (~20KB min+gzip), and integrates with the JavaScript ecosystem (ES6 modules, npm, Webpack). Current stable version is 5.0.0 (released 2024-08). Release cadence: major versions (4.x, 5.x) have been stable for years; pre-release RCs and alphas are frequent (multiple per month). Differentiators: F# fidelity (most F# core library, quotations, type providers), multi-target (JS, TS, Python, Dart, Rust, Erlang/BEAM), and no runtime overhead.

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npm install fable-compiler-netcore

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INSTALL

IMPORT

SIG · FABLE-COMPILER-NET

fable-compiler-netcore

web-frameworkjavascriptv0.7.42

harness data pending

Install & Compatibility

Where this runs

No compatibility data collected yet for this library.

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

fable-compiler

✓ npm install -g fable-compiler

✗ npm install fable

The npm package is named fable-compiler, not fable. The CLI command is just 'fable'.

Fable.Core

✓ open Fable.Core

✗ open Fable

Core library for attributes like [<Import>], [<Emit>], etc. Separate NuGet package.

Fable.React

✓ #r "nuget: Fable.React"

✗ #r "nuget: React"

React bindings for Fable. Must reference the Fable-specific package.

Shows minimal F# project setup with Fable, including fsproj, Fable.Core reference, and CLI compilation.

// Create a simple F# project // 1. Create project.fsproj with: // <Project Sdk="Microsoft.NET.Sdk"> // <PropertyGroup> // <TargetFramework>net8.0</TargetFramework> // </PropertyGroup> // <ItemGroup> // <Compile Include="Program.fs" /> // <PackageReference Include="Fable.Core" Version="4.0.0-beta-*" /> // </ItemGroup> // </Project> // 2. Create Program.fs with: module Program open Fable.Core [<EntryPoint>] let main argv = printfn "Hello from Fable!" 0 // 3. Compile: // dotnet fable --lang JavaScript --outDir output // 4. Run output/Program.js with Node

dotnet fable --version

Debug

Known issues

breakingOptions are erased — "None" becomes null/undefined, "Some x" becomes x.

fix

Use pattern matching or Option module functions instead of null checks on options.

affects: >=1.0

breakingFable 3.0 renamed package from "fable-compiler" to "fable"? Actually the package is still "fable-compiler"; the CLI command is "fable".

fix

Install with 'npm install -g fable-compiler'; run with 'fable'.

affects: >=3.0

gotchaFable target languages: JavaScript (default), TypeScript, Python, Dart, Rust, Erlang/BEAM. Use --lang flag.

fix

Specify target language explicitly: 'dotnet fable --lang TypeScript'.

affects: >=4.0

deprecatedLegacy Fable 1.x and 2.x are obsolete; .NET Framework requirement vs .NET Core/5+.

fix

Upgrade to Fable 4.x or 5.x and use .NET SDK (net8.0+).

affects: <3.0

gotchaFable 5.0.0-rc released Aug 2024; stable 5.0.0 is final. Ensure compatibility with F# 8 and .NET 8.

fix

Use F# 8 and .NET 8 SDK for Fable 5.0+.

affects: >=5.0.0

breakingFable 5.0.0 final: Python target now uses len() instead of .length for ResizeArray (breaking).

fix

Update Python-specific code expecting .length property; use len() or .Length (which maps to len()).

affects: >=5.0.0

Errors

Common errors & fixes

fable: command not found

Installed package 'fable' instead of 'fable-compiler'.

fix

Install fable-compiler: npm install -g fable-compiler

Cannot find module 'fable-compiler'

Running 'fable' before installing, or installed locally not globally.

fix

Install globally: npm install -g fable-compiler, or use npx: npx fable-compiler

The type 'Fable.Core.ImportAttribute' is not defined

Missing reference to Fable.Core NuGet package.

fix

Add <PackageReference Include="Fable.Core" Version="*" /> to .fsproj

Upgrade

Version history

0.7.42latest on npm

Audit

Dependencies

babel-corerequiredFable uses Babel for code generation and source maps.

fsharprequiredRequires F# compiler (fsc.exe) installed on system.

Agent activity

10 hits · last 30 days

node

OpenAI (training)

Resources

githubhttps://github.com/fable-compiler/Fable ↗

packagehttps://www.npmjs.com/package/fable-compiler-netcore ↗

homepagehttps://fable.io ↗