Swift Dictionary Map Filter Reduce.swift

extension Dictionary {
    init(_ elements: [Element]){
        self.init()
        for (k, v) in elements {
            self[k] = v
        }
    }
    
    func map<U>(transform: Value -> U) -> [Key : U] {
        return Dictionary<Key, U>(Swift.map(self, { (key, value) in (key, transform(value)) }))
    }
   
    func map<U>(transform: Key -> U) -> [U : Value] {
        return Dictionary<U, Value>(Swift.map(self, { (key, value) in (transform(key), value) }))
    }
    
    func map<T : Hashable, U>(transform: (Key, Value) -> (T, U)) -> [T : U] {
        return Dictionary<T, U>(Swift.map(self, transform))
    }
    
    func filter(includeElement: Element -> Bool) -> [Key : Value] {
        return Dictionary(Swift.filter(self, includeElement))
    }
    
    func reduce<U>(initial: U, @noescape combine: (U, Element) -> U) -> U {
        return Swift.reduce(self, initial, combine)
    }
}