Depends what you're competing on. IIRC (can't view your link) OCaml/Haskell performance is much closer to Rust than it is to Python (runtime tends to like x for rust, 2x-5x for OCaml/Haskell, and 70x or more for Python) - if IshKebab's starting point was "my Python script is too slow, I need something an order of magnitude faster" then OCaml/Haskell would be competitive with Rust in that space.