[draft] whenA alternative

[a-khakimov]

#4589

[satorg]

This method does not seem doing anything with F[_] itself, so it looks like an implementation of a ternary operator, e.g.:

def x: F[A] = ???
def y: F[A] = ???

elseA(cond)(x)(y) <-> if (cond) x else y

In other words, this implementation does not seem related to Applicative (or any other typeclass in cats).

Besides, there's a convenience syntax in mouse:

import mouse.boolean.*

cond.fold(x, y)