Re: [r6rs-discuss] [Scheme-reports] redefining eqv?

[Eli Barzilay <eli@x>]

Three hours ago, Peter Kourzanov wrote:
> On Fri, 2010-12-24 at 20:49 +0900, Adrien "Pied" Piérard wrote:
> > 
> > I believe that
> > 
> > (case-with my-equality-predicate foo
> >  ((bar) quux)
> >  (else rofl)))
> 
> That's what I always do in my own code, which could be fine for a
> semi-advanced user that redefines (case) for fun. The problem is
> that the core language will lose its terseness appeal to newbies and
> veterans if you proceed this way... And Eli will be unhappy if he
> accidentally imports "wrong" (case) macro.

Please don't put words in my mouth.  If you're using an implementation
with a module system, then you can define any `case' you want without
affecting my code.


> P.S. Note that both Haskell and Scala have special devices to attack
> this problem (typeclasses resp. mixins). Not sure what ML is doing, but
> OCaml could solve this with its OO system supposedly too.

You're talking about a customized equality predicate, which is not
what `eqv?' is doing.  (The reason that `case' is using `eqv?' in the
first place is to allow efficient compilation, similar to a C
`switch' statement.)

-- 
          ((lambda (x) (x x)) (lambda (x) (x x)))          Eli Barzilay:
                    http://barzilay.org/                   Maze is Life!

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