Iavor S. Diatchki
diatchki at cse.ogi.edu
Wed Jan 21 15:05:28 EST 2004
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.
Joe Fasel wrote:
>On 2004.01.21 15:03, Iavor S. Diatchki wrote:
>>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.
>Well, except that denotationally, they are the same.
>Joseph H. Fasel, Ph.D. email: jhf at 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 at haskell.org
| Iavor S. Diatchki, Ph.D. student |
| Department of Computer Science and Engineering |
| School of OGI at OHSU |
| http://www.cse.ogi.edu/~diatchki |
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