Is there any advantage to avoiding while loops in Scala?

Question

Reading Scala docs written by the experts one can get the impression that tail recursion is better than a while loop, even when the latter is more concise and clearer. This is o

Answer 1

In general, a directly tail recursive function (i.e., one that always calls itself directly and cannot be overridden) will always be optimized into a while loop by the compiler. You can use the @tailrec annotation to verify that the compiler is able to do this for a particular function.

As a general rule, any tail recursive function can be rewritten (usually automatically by the compiler) as a while loop and vice versa.

The purpose of writing functions in a (tail) recursive style is not to maximize performance or even conciseness, but to make the intent of the code as clear as possible, while simultaneously minimizing the chance of introducing bugs (by eliminating mutable variables, which generally make it harder to keep track of what the "inputs" and "outputs" of the function are). A properly written recursive function consists of a series of checks for terminating conditions (using either cascading if-else or a pattern match) with the recursive call(s) (plural only if not tail recursive) made if none of the terminating conditions are met.

The benefit of using recursion is most dramatic when there are several different possible terminating conditions. A series of if conditionals or patterns is generally much easier to comprehend than a single while condition with a whole bunch of (potentially complex and inter-related) boolean expressions &&'d together, especially if the return value needs to be different depending on which terminating condition is met.