On Sun, Aug 8, 2010 at 5:47 PM, bluestorm <bluestorm.d...@gmail.com> wrote:
> >> > > Is there a better approach to polymorphic equality floating around? > >> > > >> > Besides type classes? I'm not sure. It's probably possible to remove > >> > this feature from the language, with a little bit of syntactic > >> > overhead to pass around a matching comparison function. > >> > >> Yes for instance the very concise local opening notation comes in handy > >> here: > >> > >> if Int.(x = 42) then ... else ... > > > > That's very nice. I don't think type classes are conservative enough for > > this project, but this comes very close indeed. > > I haven't really had a chance to explore OCaml 3.12 yet, as it came out > > while I was working on this, but I will give this serious consideration. > > This approach is very nice indeed, but to make it practical you have > to have one of the two following features : > - a more restricted form of "open" statement that does not blindly > import *all* the module values > - nested modules > > If you don't have any of these, you have to declare infix operators > directly inside the module. You'd have a "val (=) : int -> int -> > bool" in the "int.ml" file for example. That's notoriously painful to > handle if you use the "open" statement : a bunch of "open" statements > in a non-careful order and your infix operators become unusable > because you don't know anymore where they come from. What you really > need is some form of "explicit open", à la Python or Haskell, such as > "from Int import (mod, of_char, to_char)" instead of the full open : > only a few identifiers are unqualified, and you still use Int.(=), > Int.(+) instead of polluting the global namespace. > I don't believe there is really any issue here. Certain modules are simply not intended to opened to be opened globally. This is already the case: witness the many standard library modules that define "length", "map", "iter", etc. -Jeremy
_______________________________________________ Caml-list mailing list. Subscription management: http://yquem.inria.fr/cgi-bin/mailman/listinfo/caml-list Archives: http://caml.inria.fr Beginner's list: http://groups.yahoo.com/group/ocaml_beginners Bug reports: http://caml.inria.fr/bin/caml-bugs
