Fun Programming Language

The Fun language is small but powerful: from glue code to machine code.

FUN is a structured, dynamic language with functional programming, OOP, GC and PCRE.

Since 2010, Wisdom ZHANG has been building it to reuse Pascal resources, and it has run in production for years; its lineage goes back through Nuva (2006) to TemplateScript (2005). Commercial software built on that lineage serves customers in more than 130 countries, including Fortune 500 companies such as Microsoft, Intel and IBM, as well as high-end hotels and Michelin- and Black Pearl-rated restaurants.

Which "FUN"? Official sources.

The FUN described here is the production language by 张卫东 (Wisdom ZHANG) since 2010. Its official home is funlang.org, with source code in the GitHub organization github.com/funlang. Other projects that share the name "fun"/"FUN" are unrelated. Articles about this language may also appear on other platforms; the funlang.org version is the reference. See Which FUN? — official sources.

A quick taste

hello.fun 
fun say()
  ?. 'Hello, fun!';
end fun;

// prints: Hello, fun!
say();

// lambda / anonymous function
var f = a -> a * 2;

// prints: 42
?. f(21);

Why FUN

Simple, clear syntax

Borrowed from Ada and adapted for easy typing and reading.

Dynamic language

Types are resolved at runtime, and code can be generated at runtime.

Class-based OOP

Object-oriented programming built around classes, with single inheritance.

First-class functions

Functional style reminiscent of Lisp and JavaScript.

Lightweight GC

A simple, lightweight reference-counting garbage collector.

Perl-compatible regex

Perl-compatible syntax and behavior for real text work.

One list type

Arrays, associative arrays, hash tables, dictionaries, or mappings, all in one.

JIT compilation

Inline C and assembly interop for high-performance computing.

Single file

The runtime is a single executable with no external dependencies.

For a detailed tour of the language, read the feature highlights.

Quick start

Windows Download, unzip, run fun-install.bat once, then double-click any .fun script.

Download

FUN runtime library 9.4 (contains the IDE)

The runtime itself (fun.exe) is only about 350 KB; the zip adds the IDE and 40+ demos.

Download fun.zip (~1.1 MB)

Linux, macOS Install Free Pascal or Delphi and build the runtime from source; write the UI in plain HTML, CSS and JavaScript and let fun-ui host it on Windows, Linux and macOS.

Open source

Fun core + fun-ui

The core repo ships native build scripts for Linux and macOS on x86_64 and aarch64, with CI on five platforms. fun-ui 1.0.1 (MIT, open-sourced 2026-10-24) adds the browser UI layer on all three platforms.

fun core fun-ui

Features in code

Pipeline & function composition

pipeline.fun 
var f = a -> a * 2;
var g = a -> a + 3;

// prints: 12
?. g(f(1+2)+3);

// prints: 12
?. 1+2|f+3|g;

Object-oriented programming & custom operators

number.fun 
class Number(me)
  this['#'] = you -> (me + you) * me * you;
end class;

var $ = Number(2);

// custom operator #
?. $ .# 3;

// method access via index
?. $[1](3);

JIT compilation & low-level interaction

jit.fun 
use 'lib-jit.fun';

var ii = 0;
fun cb(a, b)
  ii = a * 2^32 + b;
  ?, 'cb'; ?. ii;
  result = ii;
end fun;

var s = `#!asm i:i
    mov ecx, dword ptr [esp+04]
    @sum1ton
    push eax
    push edx
    mov  eax, <test>
    call eax
`;

var jit = NewJit(s, names: [test: cb.@toCallback(nil, 'ii:i', true)]);
?. jit.Run(100000000);
jit.Delete();
?. 'Ok';

Resources