What are Swift's counterparts to JavaScript's Array.some() and Array.every()?

Question

Swift provides map, filter, reduce, ... for Array\'s, but I am not finding some (or any) or

Answer 1

To replace any/some, you can use SequenceType's contains method (there's one version which takes a boolean predicate; the other one takes an element and works only for sequences of Equatable elements).

There's no built-in function like all/every, but you can easily write your own using an extension:

extension SequenceType
{
    /// Returns `true` iff *every* element in `self` satisfies `predicate`.
    func all(@noescape predicate: Generator.Element throws -> Bool) rethrows -> Bool
    {
        for element in self {
            if try !predicate(element) {
                return false
            }
        }
        return true
    }
}

Or, thanks to De Morgan, you can just negate the result of contains: !array.contains{ !predicate($0) }.

By the way, these work on any SequenceType, not just Array. That includes Set and even Dictionary (whose elements are (key, value) tuples).