This is why Optionals should not be allowed in if statement tests

OptionalFail.swift

val shouldLaunchMissiles : Bool? = false

// A million lines later, programmer forgets that shouldLaunchMissiles is an optional
if shouldLaunchMissiles {
    println("The only way to win is not to play")
    missiles.launch()
} else {
    println("Let there be peace on Earth")
    kittens.release()
}

// Confusingly, if you add a "no-op" comparison it works (optionals implicitly unwrap in this case)
if shouldLaunchMissiles == true {
    println("The only way to win is not to play")
    missiles.launch()
} else {
    println("Let there be peace on Earth")
    kittens.release()
}