Thank you @snowleopard for a very balanced Haskell/OCaml comparison. I could have written it myself 
I know. This comes straight from Milner’s original LCF ML design. You’ll find the same oddity in Standard ML. My guess is that if you’re a native English speaker, “an integer list” rolls off the tongue more easily than “a list of integer”, hence “int list” instead of “list(int)”. As a native French speaker I would say “une liste d’entiers” (list int), and as a mathematician I would write “list(int)”.