Using recursion instead of for loops / list comprehension

[ndc85430]

There is another thing to mention. Even though in Haskell, you don't have loops, that doesn't necessarily mean you'd always write something recursively. I'm not a Haskell programmer, but I do work in functional languages and your particular example is really just naturally expressed using map (in fact, your list comprehension is pretty much Python's equivalent of calling map in other languages. Well, it would be if you used the step argument to range instead of filtering in the even values). Whether that is done iteratively or recursively likely isn't your concern. Your example implemented in Clojure for example would look like

 
user=> (range 0 10 2)
(0 2 4 6 8)
user=> (defn double-it [x] (* 2 x))
#'user/double-it
user=> (map double-it (range 0 10 2))
(0 4 8 12 16)