Given that your motivation was, as an exercise, to “get familiar with binary pattern matching” your use of recursion is justifiable. However when looking for “the right tool for the job” I don’t believe that “easier to do” was the sole motivation of using String.split, Enum.map, and Enum.join in Dave Thomas’ possible solution (though it certainly is a valuable bonus).
I personally suspect that it has something to do with what Michael Fogus discusses in his blog post Recursion is a low-level operation - the essence of which seems to be “Prefer use of higher order functions over recursion”. Now granted the blog is in the context of Clojure and the JVM but it seems to align with the general notion that higher level abstractions tend to lead to better solutions. So while it is certainly important to know how to effectively use recursion, it is just as important to know when not to use it. Don’t let recursion become your golden hammer; attempt to seek out better options whenever possible.
