Optional.map/flatMap

gistfile1.swift

// https://twitter.com/akisutesama/status/596501848313372672
// https://twitter.com/_ishkawa/status/596504826655088640

var god: String? = "god"

func makeItFuck(x: String) -> String {
    return x + " fuck"
}

var godfuck1 = god.map { $0 + " fuck" } // String?
var godfuck2 = god.map { x -> String? in x + " fuck" } // String??
var godfuck3 = god.map { Optional($0 + " fuck") } // String??
var godfuck4: String?? = god.map { $0 + " fuck" } // String??, closure is inferred as (String -> String?)
var godfuck5 = god.map(makeItFuck) // String?

var flatgodfuck1 = god.flatMap { $0 + " fuck" } // String?
var flatgodfuck2 = god.flatMap { x -> String? in x + " fuck" } // String?
var flatgodfuck3 = god.flatMap { Optional($0 + " fuck") } // String?
var flatgodfuck4 = god.flatMap { x -> String in x + " fuck" } // Can not compile
var flatgodfuck5 = god.flatMap(makeItFuck) // Can not compile