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[Caml-list] User-defined equality on types?
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Date: | 2001-04-24 (08:33) |
From: | Andreas Rossberg <rossberg@p...> |
Subject: | Re: [Caml-list] User-defined equality on types? |
Brian Rogoff wrote: > > On Mon, 23 Apr 2001, Xavier Leroy wrote: > > > I'd like to suggest allowing the user to define a chosen interpretation > > > of the equality symbol, and perhaps the polymorphic orderings too, on > > > each new (maybe just abstract) data type. This seems natural in the > > > context of abstract data types with non-canonical representation, giving > > > a kind of quotient type. Has this ever been considered? > > > > Yes. This was one of the first motivations for Haskell type classes, > > I believe. > > Would the proposed generic polymorphism extension solve this problem? Probably not, because unlike type classes generic functions are closed and do not allow adding cases for new types later on. -- Andreas Rossberg, rossberg@ps.uni-sb.de "Computer games don't affect kids. If Pac Man affected us as kids, we would all be running around in darkened rooms, munching pills, and listening to repetitive music." ------------------- To unsubscribe, mail caml-list-request@inria.fr. Archives: http://caml.inria.fr