Attempt on Functor in Rust

typeshi.rs

trait Higher<U> {
    type C;
    type T;
}

impl<U, T> Higher<U> for Vec<T> {
    type C = T;
    type T = Vec<U>;
}

trait Functor<U>: Higher<U> {
    fn fmap<F>(&self, f: F) -> Self::T
    where
        F: Fn(&Self::C) -> U;
}

impl<T, U> Functor<U> for Vec<T> {
    fn fmap<F>(&self, f: F) -> Vec<U>
    where
        F: Fn(&T) -> U,
    {
        let mut result = Vec::with_capacity(self.len());
        for value in self {
            result.push(f(value));
        }
        result
    }
}

fn main() {
    let example = vec!["some"];
    let transform = example.fmap(|v| v.to_string());

    println!("{:?}", transform);
}