Increment_Decrement_Operators.swift

Reimplements ++ and -- operators in Swift 3

prefix operator ++
prefix operator --
postfix operator ++
postfix operator --

@discardableResult prefix func ++( a: inout Int) -> Int {
    a += 1
    return a
}

@discardableResult prefix func --( a: inout Int) -> Int {
    a -= 1
    return a
}

@discardableResult postfix func ++( a: inout Int) -> Int {
    defer { a += 1 }
    return a
}

@discardableResult postfix func --( a: inout Int) -> Int {
    defer { a -= 1 }
    return a
}