Fun Programming Language

Fun is a statically-typed programming language that transpiles to C, designed for safety, performance, and simplicity. Written in Zig.

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Table of Contents

• Fun Programming Language
  • Table of Contents
  • Features
  • Installation
  • Release installers (bundles)
  • CLI Usage
  • Quickstart
  • Examples
  • Project Structure
  • Contributing
  • Changelog
  • License
  • IDE / Language Server (fls)
    • VS Code
  • Installation
    • Prerequisites
    • Build from Source
    • Install from Release

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Features

• Statically-typed, C-like performance
• Transpiles to readable C code
• Simple, expressive syntax
• Modular imports
• Pattern matching (fit statement)
• Type-safe variables and functions
• CLI with multiple output and debug options
• AST printing and analysis
• Comprehensive error handling
• Example and test suite

Installation

Requires Zig (v0.14.0+ recommended).

zig build

This will build the fun compiler in zig-out/bin/fun.

To install the compiler plus the Fun standard library files:

zig build install

This installs:

• zig-out/bin/fun
• zig-out/share/fun/stdlib/std/c/*.fn (signature-only C-interop modules used for tooling)

Notes:

• std.c.* is the C-interop layer (signatures only). These modules describe external C APIs (e.g. printf) so the compiler and language server can typecheck and provide tooling.
• std.* (without .c) is intended for Fun-native standard library modules written in Fun.

Release installers (bundles)

Release assets are packaged as install bundles (binary + share/fun/ + an installer script).

On Windows, release assets are provided as .msi installers.

The compiler discovers the standard library at runtime using, in order:

• FUN_STDLIB_DIR (explicit override)
• <exe>/../share/fun (installed layout)
• common system locations (platform-dependent)

CLI Usage

Usage: fun -in <input_file> [-out <output_file>] [-no-exec] [-outf] [-ast] [-help]

Arguments:
  -in      <file>  Input file to compile (required)
  -out     <file>  Output file (optional, defaults to input filename with .c extension)
  -no-exec         Disable automatic compilation and execution (optional, execution enabled by default)
  -outf            Generate .c output file (optional, disabled by default)
  -ast             Print AST nodes (optional, disabled by default)
  -help            Show this help message

Quickstart

Write your first program in hello.fn:

imp std.c.io;

fun main(str[] args) {
    printf("Hello, World!\n");
}

Compile and run:

zig build
./zig-out/bin/fun -in hello.fn

Examples

Explore the examples/ directory for more:

• Basic: test.fn
• Advanced: advanced/custom_functions.fn
• Imports: imports/main.fn
• Error cases: error_cases/

Project Structure

• cmd/ — CLI entrypoint
• modules/ — Core compiler modules (lexer, parser, codegen, semantics, utils, etc.)
• examples/ — Example programs
• tests/ — Test suite
• build.zig — Zig build script

Contributing

Contributions are welcome! Please open issues or pull requests. See CONTRIBUTING.md if available.

Changelog

See CHANGELOG.md for release notes and development history.

License

This project is licensed under the MIT License. See the LICENSE file for details.

IDE / Language Server (fls)

This repo includes a work-in-progress language server called fls.

• Build: zig build (installs fls alongside fun)
• The server speaks LSP over stdio and currently supports:
  • Diagnostics (via fun -no-exec)
  • Formatting (via fun -fmt -no-exec)

VS Code

There is a minimal VS Code extension scaffold in editors/vscode.

• Build fun + fls first (zig build)
• Then open editors/vscode in VS Code and follow its README.

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Installation

Prerequisites

• Zig (latest stable recommended)
• Windows, Linux, or macOS

Build from Source

Clone the repository and build using Zig:

git clone https://github.com/omdxp/fun.git
cd fun
zig build

Install from Release

Pre-built installers and binaries are available for each release. See Release installers (bundles).