Module tailcall::trampoline

This module provides a simple, zero-cost trampoline. It is designed to be used by the tailcall macro, but it can also be used manually.

Usage

Express the contents of a recusive function as a step function (Fn(Input) -> Next<Input, Output>). To guarantee that only a single stack frame will be used at all levels of optimization, annotate it with #[inline(always)] attribute. This step function and an initial input can then be passed to run which will recusively call it until it resolves to an output.

// fn gcd(a: u64, b: u64) -> u64 {
//     if b == 0 {
//         a
//     } else {
//         gcd(b, a % b)
//     }
// }

#[inline(always)]
fn gcd_step((a, b): (u64, u64)) -> tailcall::trampoline::Next<(u64, u64), u64> {
    if b == 0 {
        tailcall::trampoline::Finish(a)
    } else {
        tailcall::trampoline::Recurse((b, a % b))
    }
}

fn gcd(a: u64, b: u64) -> u64 {

    tailcall::trampoline::run(gcd_step, (a, b))
}

Re-exports

pub use Next::*;

Enums

Next	This is the output of the step function. It indicates to run what should happen next.

Functions

run	Runs a step function aginast a particular input until it resolves to an output.