ML-style module thing in Rust (please forgive me)

modules.rs

use std::hash::Hash;

pub trait Key {
  type T: Hash + Eq;
}

pub trait Map<K : Key> {
  type T<V>;

  fn new<V>() -> Self::T<V>;
  fn insert<V>(m: &mut Self::T<V>, k: <K as Key>::T, v: V);
  fn get<'a, V>(m: &'a Self::T<V>, k: &<K as Key>::T) -> Option<&'a V>;
}

mod hash_map {
  use std::collections::HashMap;

  use super::*;
  
  pub struct Make;
  pub struct Wrapper<K, V>(HashMap<K, V>);

  impl<K: Key> Map<K> for Make {
    type T<V> = Wrapper<<K as Key>::T, V>;

    fn new<V>() -> Self::T<V> {
      Wrapper(HashMap::new())
    }

    fn insert<V>(m: &mut Self::T<V>, k: <K as Key>::T, v: V) {
      m.0.insert(k, v);
    }

    fn get<'a, V>(m: &'a Self::T<V>, k: &<K as Key>::T) -> Option<&'a V> {
      m.0.get(k)
    }
  }
}

fn main() {
  pub struct K;

  impl Key for K {
    type T = &'static str;
  }

  let mut m = <hash_map::Make as Map<K>>::new();
  <hash_map::Make as Map<K>>::insert(&mut m, "x", 3);
  <hash_map::Make as Map<K>>::insert(&mut m, "y", 42);
  assert_eq!(<hash_map::Make as Map<K>>::get(&mut m, &"x"), Some(&3));
  assert_eq!(<hash_map::Make as Map<K>>::get(&mut m, &"y"), Some(&42));
}