OCaml has monadic let syntax[1] which is similar to F#'s computation expressions. I am not sure why it is not yet supported in Reasonml/Bucklescript.
[1] http://jobjo.github.io/2019/04/24/ocaml-has-some-new-shiny-s...
[1] http://jobjo.github.io/2019/04/24/ocaml-has-some-new-shiny-s...
https://github.com/rescript-lang/ocaml "This branch is 387 commits ahead, 5444 commits behind ocaml:trunk"