Try storing an integer literal that requires 64 bits in a variable that can hold only 63 bits.
It's not going to make it impossible (you may just need something like a ShortIntLiteral and a LongIntLiteral variant), but it's going to require additional effort.
Sure, but not many real programs actually need the full 64-bits. Many of the ones that may seem to require the full bit width are doing bit ops on larger bit streams, for which there's ocaml-bitstream. What sort of programs are you thinking of?
What you are saying here is that it isn't a huge problem in practice, and I agree with that. However, that's not what the original post was saying. It said that OCaml was especially suited for writing compilers because of its ints, which is the exact opposite claim.
It's not going to make it impossible (you may just need something like a ShortIntLiteral and a LongIntLiteral variant), but it's going to require additional effort.