Pattern for mapping with identity and applying a side-effect

Question

Is there a clearer way of expressing the following pattern:

def getUser(id: String): Option[User] = ???

getUser("12345").map { user =>
  someSideEffect(user)
  user
}

Note how given a functor we map with the identity function but also apply the side-effecting function to the boxed value.

Future.andThen does exactly this:

Applies the side-effecting function to the result of this future, and returns a new future with the result of this future.

Is there something like Future.andThen but in the general case for any functor?

Answer 1

There isn't anything out of the box. People often add it with something like this:

 object ImplicitUtils {
    implicit class Utils[T](val t: T) extends AnyVal {
       def tap(f: T => Unit): T = { f(t) ; t }
    }
 }

So that, now you can write:

 import ImplicitUtils._
 val user = getUser("foo").tap(someSideEffect)