Map over an array of instances by currying an class method and then invoking the resulting functions

call.swift

extension String {
    func toUpperCase() -> String {
        return uppercaseString
    }
}

extension SequenceType {
    @warn_unused_result
    func mapByCalling<T>(@noescape transformer: (Self.Generator.Element) throws -> (() -> T)) rethrows -> [T] {
        return try self.map(transformer).map({ $0() })
    }
}


["hello", "kednny"].mapByCalling(String.toUpperCase)