[Hat] Oddness...

[Thomas Davie]

On 18 Jul 2005, at 16:58, Malcolm Wallace wrote:

> Thomas Davie <tom.davie at gmail.com> writes:
>
>
>> I've been trying to get hat-trans to eat QuickCheck, without much
>> success.  Is there something I'm missing?  I'm getting this error:
>>
>> hat-trans QuickCheck.hs
>> hat-trans: Variable or constructor not in scope: chr
>>
>
> The QuickCheck.hs module available from John Hughes' webpage was
> written for an older version of Hugs which wasn't compliant with
> Haskell'98.  The 'chr' function is exported from the standard Char
> library.
>
> However, I have to wonder whether it makes any sense to trace
> QuickCheck itself?  In the AFP summer school 2002, the students used
> QC to find a failure, then fed only that failing case into Hat to
> discover its cause.
>
> For delta-debugging, I expect you would want both a failing case and
> a passing case, but I don't suppose you really want to bother with
> tracing all the QC machinery that found them for you.

True, this was really an attempt at a first hack that involved  
running quickcheck (and thus getting multiple successes and failures  
that are easy to identify)... Look for evaluations of function  
starting prop_ and use them to do some delta debugging... Before I  
start accepting multiple traces, etc.

Bob