Language reference

Gremlin is a small language for fixed-width integer programs. It has a readable source form and a schema-version-1 JSON IR; both can represent branches and loops. Source modules can also make typed internal calls and recurse.

At a glance

Area	Contract
Values	bool, u8/u16/u32/u64, and i8/i16/i32/i64
Function interface	Zero to four integer arguments and one integer return value
Expressions	Prefix calls with explicit types—no implicit conversions, inference, casts, or infix expressions
Control flow	if, while, loop, break, and continue
Execution	A bounded, deterministic step budget and call-depth limit

A small program

fn candidate(x: u64) -> u64 {
    let a: u64 = xor(x, 0x12345678u64);
    let b: u64 = mul(a, 7u64);
    return add(b, 3u64);
}

Every operation is written as a call, and every binding declares its type. See the affine example in the repository for the complete file.

Explore the reference

• Types and literals explains values, names, and source limits.
• Operators covers fixed-width arithmetic, traps, and eager evaluation.
• Control flow introduces bindings, loops, and the source grammar.
• Functions and calls covers entry points, recursion, and backend limits.
• Execution model defines steps, outcomes, and call-depth behavior.
• IR and corpus format documents validation, canonical source, and observation identity.