method TaskClass.map Private TaskClass.map<T, E, U>(task: TaskClass<T, E>,fn: (value: T) => U | PromiseLike<U>): TaskClass<U, E> Data-first twin of TaskClass#map. const upper = Task.map(Task(() => 'fetched'), (s) => s.toUpperCase()); Type Parameters T E U Parameters task: TaskClass<T, E> fn: (value: T) => U | PromiseLike<U> Return Type TaskClass<U, E>