Camlp4 is a 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.

Camlp4 was part of the official OCaml distribution until its version 4.01.0.
Since then it has been replaced by a simpler system which is easier to maintain
and to learn: ppx rewriters and extension points.
