Not really, but the documentation will usually tell you. Also, at least in Jane Street’a libraries, exceptionful functions always end in _exn. So for example there is List.find and List.find_exn

Some people append `_exn` to names of functions which can raise exceptions; that's about it.

I don't think it's a strict convention, but it's common to see (a block of) imperative statements with side effects enclosed in:

begin ... end

It's ugly and stands out in its awkwardness, almost as if by design, with the compiler saying: "I will let you do this, but do think about it some more and try and come up with something more elegant."

I don't know, I don't write it very much.