#!/usr/local/bin/swift
func IF(PRED:()->Bool,_ THEN:()->(),_ ELSE:()->()) {
     [true:THEN, false:ELSE][PRED()]!()
}
func fact(n:Int)->Int {
    var ret:Int!
    IF( {n <= 1},
        { ret = 1 },
        { ret = n * fact(n - 1)}
    )
    return ret
}
print(fact(10))