Re: [Caml-list] [ANN] ppx_monadic.1.0.2, ppx for monadic do,

[Alain Frisch <alain@frisch.fr>]

On 01/19/2015 08:33 AM, oleg@okmij.org wrote:
>> Current OCaml syntax has shortage of pattern binding expression and
>> only usable is let%xxx p = e in which is a bit pain for ppx writers.
>
> Indeed. One may wish that
>
>          let rec p = e1 in e2
>
> were treated as if it were
>          let[@ocaml.let "rec"] p = e1 in e2
>
> and likewise let module.

Please, no!  Attributes are intended to add meta-data for external tools 
(ppx, tools parsing .cmt files, etc), perhaps also to tweak the behavior 
of the compiler (trigger/control warnings, etc), certainly not to encode 
core language features (otherwise, let's use s-expressions instead of 
Parsetree).  Facilitating language experiments is also a good use for 
attributes, but not as a long-term solution for the official compiler.

> Come to think of it, 'rec! or 'module' are
> annotations on let.

"let module" has a different shape (module 
identifiers/types/expressions) than "let".  And it doesn't seem 
realistic to merge, say, core types and module types, or core 
expressions and module expressions.


Alain