General closure operations for all types

apply.rs

trait ApplyClosure {

    fn tangent<'a>(mut self, op: |&mut Self|) -> Self {
        op(&mut self);
        self
    }

    fn apply<R>(self, op: |Self| -> R) -> R {
        op(self)
    }
}

impl<T> ApplyClosure for T {}

fn main() {
    let res = vec![2u, 3, 4]
        .tangent(|v| println!("vec {}", v))
        .iter()
        .fold(0u, |a, n| a + *n)
        .tangent(|s| println!("sum {}", s))
        .apply(|n| n * 2);
    println!("res {}", res);
}