Fibonacci and factorial functions in Rust using GMP bindings

fac_gmp.rs

extern mod gmp;
extern mod std;

use std::getopts::*;
use gmp::Mpz;
use num::Num::from_int;
use std::time::precise_time_s;

fn factorial(n: uint) -> Mpz
{
    let mut f: Mpz = from_int(1);

    let mut count = 1;
    while count <= n {
        f *= from_int(count as int);
        count += 1
    }

    f
}

fn main() {
    match getopts(os::args(), ~[reqopt(~"n")]) {
        result::Ok(ref m) => { 
            let n = uint::from_str(opt_str(m, ~"n")).get(); 
            let t0 = precise_time_s();
            let fac = factorial(n);
            let t1 = precise_time_s();
            io::println(fac.to_str());
            let t2 = precise_time_s();
            
            io::println(fmt!("calc: %f", t1 - t0));
            io::println(fmt!("print: %f", t2 - t1));
            io::println(fmt!("total: %f", t2 - t0));
        }
        result::Err(f) => { fail fail_str(f) }
    }
}

fib_gmp.rs

extern mod gmp;
extern mod std;

use std::getopts::*;
use gmp::Mpz;
use num::Num::from_int;
use std::time::precise_time_s;

fn fibonacci(n: uint) -> Mpz
{
    let mut f0: Mpz = from_int(0);
    let mut f1: Mpz = from_int(1);

    let mut count = 0;
    while count < n {
        let f2 = f0 + f1;
        f0 = f1;
        f1 = f2;
        count += 1
    }

    f0
}

fn main() {
    match getopts(os::args(), ~[reqopt(~"n")]) {
        result::Ok(ref m) => { 
            let n = uint::from_str(opt_str(m, ~"n")).get(); 
            let t0 = precise_time_s();
            let fib = fibonacci(n);
            let t1 = precise_time_s();
            io::println(fib.to_str());
            let t2 = precise_time_s();
            
            io::println(fmt!("calc: %f", t1 - t0));
            io::println(fmt!("print: %f", t2 - t1));
            io::println(fmt!("total: %f", t2 - t0));
        }
        result::Err(f) => { fail fail_str(f) }
    }
}