[Haskell-cafe] Conditional properties in QuickCheck alter test data generation?

[Duncan Coutts]

On Thu, 2008-12-18 at 20:09 +0000, Thomas Schilling wrote:
> This bug appears to be fixed in QuickCheck 2.  However, for some
> reason cabal-install by default only installs 1.2.  You have to
> explicitly ask for the newer version:
> 
>   $ cabal install QuickCheck-2.1.0.1

Or more generally:

$ cabal install 'quickcheck >= 2'

so you don't have to know exactly which version.

I'm not quite sure what to do about these cases where we've added a
global preference to keep old packages working but where it conflicts
with the principle of least surprise.

We don't necessarily want to just ignore the preference when the user
asks for it on the command line because that prevents maintainers using
it to allow stable and experimental versions of a package to be on
hackage simultaneously. However QuickCheck seems to be a case where
people now expect to use QC-2, but old packages that don't specify a
version typically only work with QC-1.x.

Duncan