Let's consider I have the following class: class A { int i, j, k; public A(int i, int j, int k) { this.i = i; this.j = j; this.k = k; } } where i, j, k have a known range: r_i, r_j, r_k. No...

I'm trying to flatMap Optionals in Java. Here is a simplified example: List<String> x = Arrays.asList("a", "b", "c"); List<String> result = x.stream().flatMap((val) -> val.equals("b...

Simple code that should check user by pass, user is active and after that update last login datetime. def authenticate() = Action.async { implicit request => loginForm.bindFromRequest.fold(...

I want to see the f function that is getting passed in map/flatmap, but no luck. I threw an an exception to see any sign of f, did not work. What is that function? how is it generated behind the sc...

In Clojure you have a function called mapcat in Clojure, which bears some similarity to flatmap in Scala. It is used to map a function to a list and return a list. In Haskell we have a function C...