[tikhonj]

It's easier to reason about performance. Since both are high-level languages, chances are expressiveness and correctness matter more, and I've found Haskell better at both, even for beginners.

OCaml had some pretty specific downsides beyond just the GIL (which is pretty absurd on its own). Typeclasses are really big, and the module system can't make up for them. OCaml also had absolutely terrible tooling and an abysmal standard library, although this has been improving pretty quickly in the last few years.

Ultimately, after having used both languages quite a bit, I just find OCaml quite a bit more awkward than Haskell. OCaml's advantages just don't make up for this, although I really love some features like polymorphic variants and modules that don't suck.

I'd still use OCaml for a few particular tasks, like web programming with the incredible js_of_ocaml, but Haskell is generally my default choice both for programming and trying to teach people.