Расширение массива словарей с помощью Swift 2.2

Question

Каков правильный способ ограничения этого расширения? Мои испытания не увенчались успехом.

Например:

extension CollectionType where Generator.Element: [T.Key:Self.Value], T: DictionaryLiteralConvertible, T.Key: StringLiteralConvertible, T.Value: Encodable { 

Answer 1

Xcode 8 бета • Свифта 3

protocol Encodable { 
    var hashValue: Int { get } 
} 
extension Int: Encodable { } 

extension Collection where Iterator.Element == [String: Encodable] { 
    var total: Int { 
     return reduce(0) {$0 + $1.values.reduce(0) {$0 + $1.hashValue}} 
    } 
} 

let dictionaries:[[String: Encodable]] = [["One":1],["Two":2],["Three":3, "Four":4]] 

dictionaries.total // 10 

---

Xcode 7.3.1 • Swift 2.2.1

protocol Encodable { 
    var hashValue: Int { get } 
} 

extension Int: Encodable { } 

extension CollectionType where Generator.Element == [String: Encodable] { 
    var total: Int { 
     return reduce(0) {$0 + $1.values.reduce(0) {$0 + $1.hashValue}} 
    } 
} 

let dictionaries:[[String: Encodable]] = [["One":1],["Two":2],["Three":3, "Four":4]] 

dictionaries.total // 10