Functions and calls

Signatures and entry points

A function takes zero to four integer arguments and returns one integer. When a module defines main, execution enters main; otherwise it enters the first declared function.

Internal call arguments are evaluated eagerly and must match the declared function signature exactly.

Recursion

Source modules can call other functions and recurse:

fn main(x: u8) -> u8 {
    return factorial(x);
}

fn factorial(n: u8) -> u8 {
    if eq(n, 0u8) {
        return 1u8;
    } else {
        return mul(n, factorial(sub(n, 1u8)));
    }
}

See the full recursion example in the repository.

Calls and callee returns each cost one execution step. The execution model defines the shared call-depth budget and the CLI’s default limit.

Backend support

The CPU module evaluator supports internal calls. GPU, formal, and LLVM backends currently reject them. See Supported features when choosing an execution or verification workflow.