перемудрил?

#![feature(specialization)]

use std::marker::PhantomData;

pub trait PHash<T> {
    fn new() -> T;
}

// pub trait PHashFun<K,V> {
//     fn 
// }

pub struct PHashMap<T>(T);
pub struct PHashMapDef<K,V> {
    keys: Vec<K>,
    vals: Vec<V>
}
pub struct PHashMapSimple<K,V> {
    phantom: PhantomData<K>,
    vals: Vec<Option<V>>
}

impl<K,V> PHash<PHashMap<PHashMapDef<K,V>>> for PHashMap<PHashMapDef<K,V>> {
    default fn new() -> PHashMap<PHashMapDef<K,V>> {
        PHashMap(PHashMapDef {
            keys: Vec::new(),
            vals: Vec::new()
        })
    }
}

impl<V: Clone> PHash<PHashMap<PHashMapSimple<u8,V>>> for PHashMap<PHashMapSimple<u8,V>> {
    fn new() -> PHashMap<PHashMapSimple<u8,V>> {
        PHashMap(PHashMapSimple {
            phantom: PhantomData,
            vals: vec![None; std::u8::MAX as usize]
        })
    }
}

impl<K,V> PHashMap<PHashMapDef<K,V>> {
    pub fn insert(&mut self, k: K, v: V) {
        println!("insert default");
    }
}

impl<V> PHashMap<PHashMapSimple<u8,V>> {
    pub fn insert(&mut self, k: u8, v: V) {
        println!("insert u8");
        self.0.vals[k as usize] = Some(v);
    }
}