Ppxlib is the standard library for ppx rewriters and other programs that manipulate the in-memory representation of OCaml programs, a.k.a. the "Parsetree".
It also comes bundled with two ppx rewriters that are commonly used to
write tools that manipulate and/or generate Parsetree values:
ppxlib.metaquot, which allows constructing Parsetree values using the
OCaml syntax directly, and ppxlib.traverse, which provides various
ways of automatically traversing values of a given type, in particular
allowing to inject a complex structured value into generated code.
For more information about ppxlib and how to use it, please consult the documentation.
The ppx world has a long and storied history, and if you look around, you may find other projects that offer functionalities similar to ppxlib. The following blog post gives a good overview of the various libraries that have been developed over time. At this point, ppxlib is considered the de facto library for writing ppx rewriters.
This repository was created by merging several older smaller projects that were developed at Jane Street. See the history for more details.