[wg-camlp4] A set of synthetic use cases to help discussions

[Gabriel Scherer]

One problem with the current debate(s) is that people have fairly
different syntaxes and semantics in mind regarding "syntax
extensions".

I think we should gather somewhere small snippets of "representative"
syntax extensions (for example under their current form, which
includes the Camlp4 syntax extensions but also eg. Lexifi's custom
attributes syntax or the imaginary quotation system of your liking),
so that people could refer to those example and concretely demonstrate
which cases their proposed semantics would capture, and with which
syntax.

I have started to put up some examples on the following wiki page,
mostly by accumulating what has been mentioned during the discussions
so far:

  https://github.com/gasche/ocaml-syntax-extension-discussion/wiki/Use-Cases

I have made up the categories as I collected the examples, so they're
certainly suboptimal.

The page should be open for editing (let me know if the right aren't
set correctly), so that you can update it with new examples if you
think they are representative of some need that wasn't exposed before.
Please remember that the page is there to collect use cases for the
discussion here, rather than contain argumentation/opinion/judgments
itself.