[wg-camlp4] My uses of syntax extension

[Alain Frisch]

On 01/28/2013 06:13 PM, David Waern wrote:
> OK. I've also wanted similar syntax, but I've noticed that if Alain's
> "static exceptions" [1] proposal is accepted then encoding such things
> using existing OCaml syntax becomes a bit lighter:
>
> try raise (`Cont expr) with
> | `Cont n -> expr
> | handlers

As a side note, this encoding with static exceptions is also much more 
efficient (no allocation required to escape from the exception handler).

Still, this is a good example.  One might indeed want to use a dedicated 
syntax for this common idiom.  My preference would be for extending the 
official language to support it directly.  If one thinks it is generally 
useful, why not put it in the language itself?  It is not difficult to 
extend OCaml to support it directly.

If the proposal is rejected but we have let-fix operators, one can 
decide to have a -ppx rewriter detecting and rewriting the following form:

let? x = try e1 with p -> e2 in
e3


-- Alain