[Caml-list] Deepest Lexically Faithful OCaml Syntax Folds

[David Sheets <sheets@alum.mit.edu>]

Hello World,

I am searching for the "deepest lexically faithful OCaml syntax
catamorphism solution" as the title indicates. What precisely do I
mean by this?

Deepest => most semantically abstract while retaining a map back to syntax
Lexically faithful => injective, accurate, coordinate-tracked tokens
OCaml syntax => a fine conjuring form
Catamorphism => the source annotations occur as reserialization folds
of some kind
Solution => relatively cheap to integrate

Specifically, I am looking for a collection of functions like:

ana ocaml_parse : string -> '_a
cata : '_a -> (('_a -> '_b) * ('_b list -> '_b)) -> '_b
cata' : '_b -> (('_b -> '_c) * ('_c list -> '_c)) -> '_c
.
.
.
serialize : '_c -> ('_c -> string) -> string

where ana's domain is OCaml source code and cata''s range is (possibly
annotated) OCaml source (which may not be valid for reconsumption
without further processing). The multiplication operator's signature
may vary.

such that the weakly polymorphic types above can be mapped over by
adding arbitrary annotations. Any number of catamorphic levels is
acceptable. OCaml 3.12 and 4.x syntax support necessary.

Is the answer some invocation of camlp4, ppx, fan, or compiler
internals? Am I asking for something nonsensical? Have you already
implemented something similar? Do functions equivalent to these exist
in a tool of which you know?

Thank you,

David