Simple Chain outline

chain1.rs

fn add_one(n: int) ⟶  int {
    n + 1
}

fn times_two(n: int) ⟶  int {
    n * 2
}

fn chain<A,B,C>(f1: ~fn(a: A) ⟶  B,f2:  ~fn(b: B) ⟶  C) ⟶  ~fn(A) ⟶  C { 
    |x: A| { 
        f2(f1(x)) 
    } 
}

fn main() {
    let plus_one_times_two = chain(add_one,times_two);
    let times_two_plus_one = chain(times_two,add_one);

    let res1 = plus_one_times_two(50);
    let res2 = times_two_plus_one(50);

    println(fmt!("plus_one_times_two(50) = %d",res1));
    println(fmt!("times_two_plus_one(50) = %d",res2));
}


// Output
// plus_one_times_two(50) = 102
// times_two_plus_one(50) = 101