Re: [Caml-list] Is this the right place to discuss camlp5?

[Hendrik Boom <hendrik@topoi.pooq.com>]

On Mon, Oct 26, 2015 at 02:27:23PM +0000, David Allsopp wrote:
> Hendrik Boom wrote:
> > On Mon, Oct 26, 2015 at 01:35:45PM +0000, Soegtrop, Michael wrote:
> > > Dear Ocaml Users,
> > >
> > > I just wanted to ask, if this is the right place to discuss camlp5, or
> > if there is a better place. I have a rather bizarre build issue on Cygwin
> > and a fix (well a hack) for it.
> > 
> > Now I've heard about campl5, presumably a successor to campl4, and about
> > ppx, touted as a successor to camlp4.
> 
> In fact, camlp5 is technically the predecessor of camlp4! camlp4 was incompatibly re-worked for OCaml 3.10 (I think it was 3.10, anyway) - Daniel De Rauglaudre, the author of the original camlp4 but at that time not its maintainer, decided to continue development of the original camlp4 but, to avoid creating even more hell in the upgrade to OCaml 3.10, renamed the tool to camlp5. So camlp5 is basically a maintained fork of an older version of camlp4.
> 
> ppx is a much more recent innovation designed to replace most uses of both those tools. Which is at least part of the reason that camlp4 is no longer included in mainline OCaml.
> 
> > What gives here?
> 
> History! And also that converting between camlp4/camlp5/ppx is non-trivial. If doing something new, and you don't need to worry about older OCamls, ppx is the way to go...

How incomptible are they?  I don't expect to be able to use ppx in 
the place of camlp4 on camlp4 code, but is there any difficulty
combining legacy code written using camlp4 with new code written 
using ppx?

-- hendrik