The use of camlp{4,5} to change OCaml syntax has always had extremely low
adoption, with some very specific exceptions (notably the lwt-support
syntax of the Ocsigen project). I suspect that this is due to the fact that
integrating a new syntax extension to your project has historically caused
more build-system and deployment trouble than people were willing to
tolerate.

ppx extensions are not designed to allow extending the OCaml syntax, and in
particular I think they are not a good fit for what you are looking for. It
is a large part of their appeal: by being less flexible, they are simpler
and more robust.

I personally believe that currified constructor syntax would be a better
choice, and that using non-currified constructors is a historical mistake
of SML/Caml. But I am also not convinced that efforts to change it today
are worth the trouble, and prefer to concentrate on improving other parts
of the OCaml ecosystem.

Another thing that was touched by your comments is the usefulness of
user-defined patterns (pattern synonyms). I have conflicted opinions on the
question of whether adding pattern synonyms would be a good thing, but
described one aspect of a proposal that I like (but also highlights that
the feature can be a source of implementation complexity) in
  http://gallium.inria.fr/blog/pattern-synonyms-as-expressions/

On Fri, Nov 6, 2015 at 1:20 PM, Soegtrop, Michael <
michael.soegtrop@intel.com> wrote:

> Dear Francois,
>
> > let constr a b = Constr (a, b)
>
> unfortunately this won't work for matches. I will see if I get used to
> this. If not I will take this as a reason to learn p5 and/or ppx :-)
>
> Best regards,
>
> Michael
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