[Haskell-cafe] Libraries of standard QuickCheck properties
lrpalmer at gmail.com
Thu Aug 21 18:01:48 EDT 2008
2008/8/21 Sean Leather <leather at cs.uu.nl>:
> This in response to a comment on a GHC ticket . I thought it was
> interesting enough to warrant general discussion.
>> Comment (by JeremyShaw):
>> > Also, where does the H98 report say all instances of Eq must be
>> transitive, reflexive, symmetric, and antisymmetric? It just says "The Eq
>> class provides equality (==)..", whatever that might mean :-)
>> Well, it does not say it explicitly, but I suspect H98's usage of Eq
>> implicitly demands those laws be followed.
> Indeed. The same goes for the implicit law that (x /= y) /= (x == y), since
> both (/=) and (==) can be overridden. 
>> Hopefully in Haskell' the laws
>> will not only be stated, but there will be some QuickCheck-style
>> properties you can use to test your own instances ;)
> This is an interesting thought. Has there been any work towards collecting
> properties written with QuickCheck (or similar) into a reusable chunk of
> some form?
Yes, it's in development, called 'checkers'. code.haskell.org/checkers
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