Re: [Caml-list] camlp4 & OCaml 4.08

["Richard W.M. Jones" <rich@annexia.org>]

On Sat, Jun 29, 2019 at 10:06:15AM +0100, Anil Madhavapeddy wrote:
> On 27 Jun 2019, at 14:45, Richard W.M. Jones <rich@annexia.org> wrote:
> > 
> > 
> > I know camlp4 is dead and all that, but we've got some software which
> > still uses it.  I will probably port it to camlp5 when I have the
> > time, but has anyone got the patch to make camlp4 work with 4.08?
> 
> 
> To fork the thread slightly,  how big are the camlp4 dependencies remaining
> in your codebase, and is there anything we can do to help migrate?

The dependencies that I care about run through ocaml-gettext.  Gettext
is a specific method to make code internationalized and by its nature
it involves deep changes throughout our codebase, so porting away from
ocaml-gettext isn't an option any time soon.  However porting
ocaml-gettext to use something else might be.

ocaml-gettext has a tool which runs over the OCaml source code and
extracts the magic translatable strings, and it's my understanding
that this is the only reason it uses camlp4.  AIUI this cannot be done
using ppx's (maybe I'm wrong about that?) but could be done using
camlp5.  In fact it was me who did the original port of ocaml-gettext
from old camlp4 (ie. camlp5) to camlp4(!)

(see libgettext-ocaml/pr_gettext.ml in the OCaml sources)

> It's pretty exhausting trying to keep camlp4 maintained with a skeleton
> crew, and there appears to be a stubborn tail of packages which aren't
> migrating despite it having been quite a few years since the deprecation.

I agree, however also changing working code is always a pain and
there's never a good time.

Rich.