One common critique is that in the toplevel (REPL) you must terminate your inputs by ;; and sometimes you will see code that puts ;; between function definition

One common critique is that in the toplevel (REPL) you must terminate your inputs by ;; and sometimes you will see code that puts ;; between function definitions too. Also, nesting pattern matches is a bit ugly: match x with | Foo y -> match y with | Yes -> ok () | No -> not_ok () | Bar z -> whatever() does not work, it must be: match x with | Foo y -> begin match y with | Yes -> ok () | No -> not_ok () end | Bar z -> whatever() which is not a big deal but surprisingly easy to forget. Some people would also really like to write let x = foo let y = bar x + y but it has to be let x = foo in let y = bar in x + y and those many "in"s accumulate. A bunch of these things look a lot cleaner in Haskell. Although it does it by being indentation-sensitive, which other people love hating.