Cppo is an equivalent of the C preprocessor targeted at the OCaml language and
its variants.

The main purpose of cppo is to provide a lightweight tool for simple macro
substitution (#define) and file inclusion (#include) for the occasional case
when this is useful in OCaml. Processing specific sections of files by calling
external programs is also possible via #ext directives.

The implementation of cppo relies on the standard library of OCaml and on the
standard parsing tools Ocamllex and Ocamlyacc, which contribute to the
robustness of cppo across OCaml versions.