How to use Swift @autoclosure

Question

I noticed when writing an assert in Swift that the first value is typed as

@autoclosure() -> Bool

with an overloaded method

Answer 1

This shows a useful case of @autoclosure https://airspeedvelocity.net/2014/06/28/extending-the-swift-language-is-cool-but-be-careful/

Now, the conditional expression passed as the first parameter to until will be automatically wrapped up into a closure expression and can be called each time around the loop

func until(pred: @auto_closure ()->L, block: ()->()) {
    while !pred() {
        block()
    }
}

// doSomething until condition becomes true
until(condition) {
    doSomething()
}