You don't need an external library to print in OCaml. You just need it if you want to automate deriving a conversion function. OCaml erases types at compile time so the runtime doesn't know anything about types or how to print them. It's just how it works.

Re: better syntax frontend for OCaml. People really tried to, for many years. But it didn't work, there was never much adoption. And the funny thing was that as soon as people got comfortable with it they switched to the standard OCaml syntax because they understood it better and started preferring it. Ironic!