[m-dev.] Re: assertions

[Mark Anthony BROWN]

Fergus Henderson writes:
> 
> Mark Anthony BROWN <dougl at cs.mu.OZ.AU> wrote:
>
> > The most common usage for a declarative debugger would be to debug a
> > program with respect to its specifications.  In this case the entities
> > would be the specifications, or contracts, of the program.  There is
> > no question of their correctness --- in such a debugging session they
> > are correct by definition.
> 
> That is not how the ideal declarative debugger ought to work, IMHO.
> Certainly it makes sense for the debugger to make the working assumption
> that they are correct.  However, when the debuger gets to the point where
> it thinks it has isolated the bug to a particular program clause,
> the programmer ought to be able to ask why the debugger thinks this
> clause is buggy, and the debugger should then list all the assumptions
> that it used to prove that the clause was buggy.  The programmer should
> then be able to identify incorrect assumptions and change them.

I don't think we're actually disagreeing here.  I was talking about
correctness from the debugger's point of view; I never said that the
user should not be allowed to modify what the debugger considers correct.
Well, I never *meant* to say that  ;-).

I do think your way of looking at it is clearer, though, so I will
avoid using the term "correct" in that sense in the future.

Cheers,
Mark.
-- 
Mark Brown, PhD student            )O+  |  "Another of Fortran's breakthroughs
(m.brown at cs.mu.oz.au)                   |  was the GOTO statement, which was...
Dept. of Computer Science and Software  |  uniquely simple and understandable"
Engineering, University of Melbourne    |              -- IEEE, 1994
--------------------------------------------------------------------------
mercury-developers mailing list
Post messages to:       mercury-developers at cs.mu.oz.au
Administrative Queries: owner-mercury-developers at cs.mu.oz.au
Subscriptions:          mercury-developers-request at cs.mu.oz.au
--------------------------------------------------------------------------