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#[macro_export]
macro_rules! compose {
( $last:expr ) => { $last };
( $head:expr, $($tail:expr), +) => {
compose_two($head, compose!($($tail),+))
};
}
pub fn compose_two<A, B, C, G, F>(f: F, g: G) -> impl Fn(A) -> C
where
F: Fn(A) -> B,
G: Fn(B) -> C,
{
move |x| g(f(x))
}
#[test]
fn test_compose() {
let add = |x| x + 2;
let multiply = |x| x * 2;
let divide = |x| x / 2;
let intermediate = compose!(add, multiply, divide);
println!("Composed Fn Result is {}", intermediate(10));
}