Rust Maybe Monad

monad.rs

use std::ops::Shr;
use Maybe::{Nothing, Just};

#[derive(Debug)]
enum Maybe<A> {
    Nothing,
    Just(A)
}

impl<A, B, F> Shr<F> for Maybe<A> where F: Fn(A) -> Maybe<B> {
    type Output = Maybe<B>;
    fn shr(self, f: F) -> Maybe<B> {
        match self {
            Nothing => Nothing,
            Just(x) => f(x)
        }
    }
}

fn main() {
    let m = 
        Just(1) >> |x| 
        Just(x + 2) >> |y|
        Just(x * 3) >> |z| 
        Just(x + y + z);
    println!("{:?}", m);
}