FactorialsOperations.swift

postfix operator ~ {}
postfix func ~(rhs : Int) -> Int {
    var result = 1
    for i in reverse(1...rhs){ result *= i }
    return result
}

infix operator ~/~ { associativity left precedence 150 }
func ~/~ (lhs : Int, rhs : Int ) -> Int {
    assert(lhs > 0, "left number < 0")
    assert(rhs > 0, "right number < 0")
    return lhs~ / rhs~
}

infix operator ~+~ { associativity left precedence 140 }
func ~+~ (lhs : Int, rhs : Int) -> Int {
    assert(lhs > 0, "left number < 0")
    assert(rhs > 0, "right number < 0")
    return lhs~ + rhs~
}

infix operator ~-~ { associativity left precedence 140 }
func ~-~ (lhs : Int, rhs : Int) -> Int {
    assert(lhs > 0, "left number < 0")
    assert(rhs > 0, "right number < 0")
    return lhs~ - rhs~
}

infix operator ~*~ { associativity left precedence 150 }
func ~*~ (lhs : Int, rhs : Int) -> Int {
    assert(lhs > 0, "left number < 0")
    assert(rhs > 0, "right number < 0")
    return lhs~ * rhs~
}
var divider = 17~/~8 //OUTPUT -> 8,821,612,800
var sum = 5~+~5 //OUTPUT -> 240
var rest = 5~-~4 //OUTPUT -> 96
var mult = 5~*~5 //OUTPUT -> 14,400