camlp4 binary package in Ubuntu Bionic i386

 Camlp4 is a software system for writing extensible parsers for
 programming languages. It provides a set of OCaml libraries that are
 used to define grammars as well as loadable syntax extensions of such
 grammars. Camlp4 stands for Caml Preprocessor and Pretty-Printer and
 one of its most important applications is the definition of
 domain-specific extensions of the syntax of OCaml.
 .
 This package contains CamlP4 executables for pre-processing and
 pretty-printing OCaml sources both interactively and in a batch
 fashion.

Source package