extension Array where Array.Element : Floopable {
    func floopAll() {
        for element in self {
            element.floop()
        }
    }
}

extension Array where Array.Element <= Floopable {
    func floopAll() {
        for floop in self {
            floop.floop()
        }
    }
}

protocol Floopable {
    func floop()
}

struct TypeA : Floopable {
    func floop() {
        print("flooping")
    }
}

struct TypeB : Floopable {
    func floop() {
        print("fl00p1ng")
    }
}

extension Array where Array.Element : Floopable {
    func floopAll() {
        (self as Array<Floopable>).eqFloopAll() // I do not like this force casting
    }
}
extension Array where Array.Element == Floopable {
    func eqFloopAll() {
        for floop in self {
            floop.floop()
        }
    }
}

let homogenousFloopables: [TypeA] = [TypeA(), TypeA()]
let heterogenousFloopables: [Floopable] = [TypeA(), TypeB()]

homogenousFloopables.floopAll() // eqFloopAll() not available
heterogenousFloopables.eqFloopAll() // floopAll() not available

(homogenousFloopables as [Floopable]).eqFloopAll() // I do not like this force casting