hello, i don't quite agree with this. if something is "undefined" as in the prelude, i should be able to prove that this is the case -- bottom is just another value, admitedly not a very nice one :-) on the other hand, if something is undefined in the specification (i.e. implementer can do whatever), than i cannot prove anything about that part of the program. in particular i cannot prove that it is bottom. i agree that this is a highly undesirable thing to have in a specification, but haskell is much better in that respect that most languages out there. -iavor Joe Fasel wrote:
On 2004.01.21 15:03, Iavor S. Diatchki wrote:
hi, not that it matters, but i think commonly when specifications say that something is undefined, that means that the behaviour can be whatever, i.e. the implementors can do what they like. this is not to be confused with the entity "undefined" defined in the Prelude. -iavor
Well, except that denotationally, they are the same.
--Joe
Joseph H. Fasel, Ph.D. email: jhf@lanl.gov Systems Planning and Analysis phone: +1 505 667 7158 University of California fax: +1 505 667 2960 Los Alamos National Laboratory post: D-2 MS F609; Los Alamos, NM 87545 _______________________________________________ Haskell mailing list Haskell@haskell.org http://www.haskell.org/mailman/listinfo/haskell
-- ================================================== | Iavor S. Diatchki, Ph.D. student | | Department of Computer Science and Engineering | | School of OGI at OHSU | | http://www.cse.ogi.edu/~diatchki | ==================================================