Hugs/GHC incompatibility

Iavor S. Diatchki diatchki at
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
>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

| Iavor S. Diatchki, Ph.D. student               | 
| Department of Computer Science and Engineering |
| School of OGI at OHSU                          |
|               |

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