Re: [Caml-list] proposal for finding, loading and composing ppx preprocessors

[Anil Madhavapeddy <anil@recoil.org>]

On 11 Jul 2014, at 15:36, Peter Zotov <whitequark@whitequark.org> wrote:
> 
> I wonder if we should just get rid of a Unix-like build pipeline entirely,
> and just make a hybrid frontend-buildsystem that would use compiler-libs
> and never execute an external OCaml process. This would make builds even
> faster and it's the logical conclusion of Alain's suggestion.

I prototyped one of these a couple of years ago while trying to speed up
the Mirage build system, but required some extensive patching of the compiler
sources and was definitely not suitable for upstreaming.

These days, much of the required functionality is exposed via the
compiler-libs package, so it should be possible to have a go at this
much more easily.

Personally, I'd love to see the use of Sys replaced with the Irmin Git
library database (http://github.com/mirage/irmin).  This would allow a model
where the ML sources are imported into a Git DAG, passed through to the 
compiler-libs as an in-memory structure, and the intermediate results 
recorded in the DAG, still all in-memory.

When the build has completed, the Irmin DAG could be dumped to disk in
the Git file format, permitting the entire build process to be inspected
if necessary (or GCed if not).  All the Git bits are currently supported
by Irmin, so this project just requires an intrepid hacker to connect
compiler-libs, Irmin, and some coordination glue.

-anil