Tiny Result type in Swift

TinyResult.swift

// Credit: Hooman Mehr via swift-evolution
// https://lists.swift.org/pipermail/swift-evolution/Week-of-Mon-20171113/041314.html

import Foundation

public enum Result<Value> {
    case success(Value)
    case failure(Error)
    
    public init(_ value: Value) { self = .success(value) }
    public init(error: Error) { self = .failure(error) }
    
    public init(_ expression: @autoclosure () throws -> Value) {
        do {
            self = .success(try expression())
        }
        catch {
            self = .failure(error)
        }
    }
    
    public init(_ closure: () throws -> Value) {
        do {
            self = .success(try closure())
        }
        catch {
            self = .failure(error)
        }
    }
    
    public func get() throws -> Value {
        switch self {
        case let .success(value): return value
        case let .failure(error): throw error
        }
    }
    
    public func map<U>(_ transform: (Value) throws -> U) throws -> U {
        return try transform(get())
    }
    
    public var value: Value? {
        switch self {
        case let .success(value): return value
        case .failure: return nil
        }
    }
    
    public var error: Error? {
        switch self {
        case .success: return nil
        case let .failure(error): return error
        }
    }
}

TryResultUsage.swift

func doSomething() -> Result<String> {
    return Result("Done!")
}

let result = doSomething()
do {
    let value = try result.get()
    print(value)
}
catch {
    print(error)
}