package ppx_ast

README.org

#+TITLE: ppx\_ast
#+PARENT: ../README.md

Ppx\_ast selects a specific version of the OCaml Abstract Syntax Tree
from the [[https://github.com/let-def/migrate-parsetree][migrate-parsetree]] project that is not necessarily the same
one as the one being used by the compiler.

It also snapshots the corresponding parser and pretty-printer from the
OCaml compiler, to create a full frontend independent of the version
of OCaml.

This AST is used in all Jane Street ppx rewriters, and more generally
in all Ppx\_core/Ppx\_driver based ppx rewriters. Using a different
ASTs allows to "detach" the ppx code from the compiler libraries, and
allow to use ppx rewriters with new compilers before upgrading the ppx
code.