Warning

Keel is under active development

Keel is a fast, statically-typed interpreted language that aims to combine Rust-like syntax with Python's ease-of-use.

Its goal is to provide a faster alternative to Python that sits closer to low-level languages while remaining accessible to a wide audience.

Contributions and issues are welcome!

Website Documentation Try Keel in your browser

Why Keel?

• Fast: ~2-15x faster than Python (benchmarks), with aggressive compile-time optimizations
• Familiar syntax: Rust-like, with Python's ease-of-use
• Statically typed, zero annotations: full type inference, static type checking, polymorphism
• FFI support: call C/dynamic libraries directly from Keel
• Built-in REPL

Browse examples

Quick showcase

struct Point { x: int, y: int }

fn add(a, b) {
    return a + b;
}

fn main() {
    let p = Point { x: 3, y: 4 };
    print(add(p.x, p.y)); // 7
    print(add("Hello, ", "world!")); // Hello, world!

    let nums = [4, 2, 6, 1, 7];
    if nums[0] == 4 {
        nums.sort();
        print(if nums[0] == 1 { nums[0..3] } else { -1 }); // [1,2,4]
    } else {
        throw("Error!");
    }
}

Benchmarks

Installation

macOS / Linux

curl -fsSL https://raw.githubusercontent.com/horacehoff/keel/main/install.sh | sh

Windows

Download the latest .zip from the releases page and add the binary to your PATH.

Build from source (without PGO)

Make sure Rust is installed.

git clone https://github.com/horacehoff/keel && cd keel && cargo build --release
./target/release/keel myfile.kl

Usage

keel program.kl    # Run a file
keel               # Start the REPL
keel -v/--version  # Print version
keel -h/--help     # Print help

Near-future roadmap

• Better, more helpful errors
• Better module system
• Struct methods
• Proper higher-order functions implementation
• Better embedding API with limits