Re: [Haskell-beginners] Quickcheck2 - writing a modifier for test data

31 Mar 2013


      On Sun, Mar 31, 2013 at 12:21:48PM +0200, Nathan Hüsken wrote:
...
No instance for (QuickCheck-2.4.2:Test.QuickCheck.Arbitrary.Arbitrary
                       ValidPos)
The fact that it actually lists the package and version number in the
error message strongly suggests that the problem is conflicting
versions of the QuickCheck package.  Do 'ghc-pkg list QuickCheck' to
see if you have multiple versions installed, and unregister all but
one of them.

-Brent

Re: [Haskell-beginners] Quickcheck2 - writing a modifier for test data

Brent Yorgey