Source code in the swift programming language

func func1(f: String->String) -> String { return f("a string") }
func func2(s: String) -> String { return "func2 called with " + s }
println(func1(func2)) // prints "func2 called with a string"

func func3<T>(f: (Int,Int)->T) -> T { return f(1, 2) }
println(func3 {(x, y) in x + y}) // prints "3"