Key value pairing with support for equality, hashing and coding

KeyValuePairs.swift

extension Dictionary {
    public typealias KeyValuePairs = [KeyValuePair<Key, Value>]
    public var keyValuePairs: KeyValuePairs { map(KeyValuePair.init) }
}

extension Collection where Element: KeyValuePair_P {
    public var dictionary: [Element.Key: Element.Value] { Dictionary(uniqueKeysWithValues: map(\.tuple)) }
}

public protocol KeyValuePair_P {
    
    associatedtype Key: Hashable
    associatedtype Value
    
    var key: Key { get }
    var value: Value { get }
}

extension KeyValuePair_P {
    public var tuple: (Key, Value) { (key, value) }
}

public struct KeyValuePair<Key, Value>: KeyValuePair_P where Key: Hashable {
    
    public let key: Key
    public let value: Value
    
    public init(key: Key, value: Value) {
        (self.key, self.value) = (key, value)
    }
}

extension KeyValuePair: Decodable where Key: Decodable, Value: Decodable {}
extension KeyValuePair: Encodable where Key: Encodable, Value: Encodable {}
extension KeyValuePair: Equatable where Key: Equatable, Value: Equatable {}
extension KeyValuePair: Hashable where Value: Hashable {}