The Dune Programming Language

Dune is a small, statically typed, compiled language with a clean C-family syntax. It has function overloading, generics with bounds, records, choices (tagged unions) with when expressions, contracts, first-class function values, lambdas and value-capturing closures, deterministic cleanup with defer, and a module system with a standard library written in Dune itself.

// Doc-comments above a declaration are shown on hover in the editor.
/// brief: Squares a value.
/// returns: value * value
fn square<T is numeric>(value: T): T {
    return value * value;
}

values: [int] = [1, 2, 3, 4];
total = values.filter(is_positive).map(square).sum();
print(total);

One front end, one backend

Dune shares a single front end — lexer, parser, type checker — feeding a single execution backend:

• A bytecode virtual machine that runs programs directly. It supports every language feature and needs no external toolchain.

How to read this book

• Language — the reference for the language itself: syntax, types, functions and generics, records, choices, modules, and comments.
• Standard library — one page per stdlib module, generated from the source doc-comments.
• Guides — building Dune, the command-line tool, the editor integration, and a tour of the runnable examples.

New to Dune? Start with Installation to build the dune binary, then read Syntax.