[Caml-list] The rec/nonrec debate

[Dario Teixeira <darioteixeira@yahoo.com>]

Hi,


As you know, there is in OCaml some asymmetry regarding the rec/nonrec 
defaults for type and value declarations.  Types are recursive by default
and there's no way to "unrecurse" them, whereas values are by default not
recursive and can be made recursive via the "rec" keyword.

The unrecursiveness of type declarations is cause for some chagrin, as a 
recent ticket on Mantis demonstrates [1].

Here's something I wonder: if one were to wipe the slate clean, is there 
consensus among the community about the best defaults?  I'm leaning towards
having nonrec as the default behaviour for *both* types and values, and
using "rec" as the keyword for recursive types and values.  This scheme
would obviate the need for an actual "nonrec" keyword.

Obviously, such a change would be too intrusive to make to OCaml.  However, 
since people are working on "Next Generation ML" languages like Mezzo [2],
I think it would be good to get the community's pulse on this subject.
(Btw, from the examples posted on Mezzo's homepage, it seems to use the
same defaults as OCaml).

Your thoughts?

Best regards,
Dario Teixeira

[1] http://caml.inria.fr/mantis/view.php?id=6016
[2] http://gallium.inria.fr/~protzenk/mezzo-lang/