* [Caml-list] Polymorphic Variants and Objects
@ 2001-12-18 14:37 Jim Farrand
2001-12-20 2:07 ` Jacques Garrigue
0 siblings, 1 reply; 3+ messages in thread
From: Jim Farrand @ 2001-12-18 14:37 UTC (permalink / raw)
To: caml-list
Take a look at the following OCaml class type definition:
class type foo =
object
method bar: [ `A | `B ]
end
I want to be able to relax the type of bar so that it can return any variant
tag, rather than being limited to `A or `B.
Is this possible? I tried
class type foo =
object
method bar: [> ]
end
but this is rejected on the grounds that
The method bar has type [> ] where .. is unbound
Any suggestions?
Regards,
Jim
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^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [Caml-list] Polymorphic Variants and Objects 2001-12-18 14:37 [Caml-list] Polymorphic Variants and Objects Jim Farrand @ 2001-12-20 2:07 ` Jacques Garrigue 2001-12-20 9:44 ` Jim Farrand 0 siblings, 1 reply; 3+ messages in thread From: Jacques Garrigue @ 2001-12-20 2:07 UTC (permalink / raw) To: jim; +Cc: caml-list From: Jim Farrand <jim@farrand.net> > Take a look at the following OCaml class type definition: > > class type foo = > object > method bar: [ `A | `B ] > end > > I want to be able to relax the type of bar so that it can return any variant > tag, rather than being limited to `A or `B. What about: class type ['a] foo = object constraint 'a = [> `A | `B] method bar : 'a end Since you want the variant to be polymorphic, you have to bind its variable somewhere. --------------------------------------------------------------------------- Jacques Garrigue Kyoto University garrigue at kurims.kyoto-u.ac.jp <A HREF=http://wwwfun.kurims.kyoto-u.ac.jp/~garrigue/>JG</A> ------------------- Bug reports: http://caml.inria.fr/bin/caml-bugs FAQ: http://caml.inria.fr/FAQ/ To unsubscribe, mail caml-list-request@inria.fr Archives: http://caml.inria.fr ^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [Caml-list] Polymorphic Variants and Objects 2001-12-20 2:07 ` Jacques Garrigue @ 2001-12-20 9:44 ` Jim Farrand 0 siblings, 0 replies; 3+ messages in thread From: Jim Farrand @ 2001-12-20 9:44 UTC (permalink / raw) To: Jacques Garrigue; +Cc: caml-list On Thursday 20 December 2001 02:07, Jacques Garrigue wrote: > Since you want the variant to be polymorphic, you have to bind its > variable somewhere. Thanks, that's exactly what I needed to know. Regards, Jim ------------------- Bug reports: http://caml.inria.fr/bin/caml-bugs FAQ: http://caml.inria.fr/FAQ/ To unsubscribe, mail caml-list-request@inria.fr Archives: http://caml.inria.fr ^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2001-12-20 9:47 UTC | newest] Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2001-12-18 14:37 [Caml-list] Polymorphic Variants and Objects Jim Farrand 2001-12-20 2:07 ` Jacques Garrigue 2001-12-20 9:44 ` Jim Farrand
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