Code shared from the Rust Playground

playground.rs

use criterion::{black_box, criterion_group, criterion_main, Criterion};
use num::{BigUint, CheckedAdd, One, Zero};
use std::iter;

const N: usize = 50000;

// (1) ジェネリック + checked_add + Option + successors 版: 元の>>295と完全に同じコード
fn fibonacci_iter_1<T: Zero + One + CheckedAdd>() -> impl Iterator<Item = T> {
    let mut oq = Some(T::one());
    iter::successors(Some(T::zero()), move |p| {
        let q = oq.take()?;
        oq = q.checked_add(p);
        Some(q)
    })
}

// >>481 iter
fn fibonacci_biguint_iter() -> impl Iterator<Item = BigUint> {
    let mut p = BigUint::zero();
    let mut q = BigUint::one();

    iter::once(p.clone()).chain(iter::from_fn(move || {
        p += &q;
        std::mem::swap(&mut p, &mut q);

        Some(p.clone())
    }))
}

pub fn criterion_benchmark(c: &mut Criterion) {
    c.bench_function("fibonacci_iter_1", |b| {
        b.iter(|| fibonacci_iter_1::<BigUint>().nth(black_box(N)))
    });
    c.bench_function("fibonacci_biguint_iter", |b| {
        b.iter(|| fibonacci_biguint_iter().nth(black_box(N)))
    });
}

criterion_group!(benches, criterion_benchmark);
criterion_main!(benches);