I'm looking for a compression library such as camlzip to read/write
compressed files (any lossless compression algorithm is fine), but having a
function similar to Pervasives.output_value, which does not seem to be
available in camlzip (and I do not see how I could easily implement it).

Would it be simple to modify camlzip to add this function? I believe that
if this were the case, then it would already have been done, but I might be
wrong.

Otherwise, is there another OCaml library with an API very similar to
Pervasives'? I'd prefer a lightweight solution (avoiding Core and
Batteries) if possible.