QuickCheck support in libraries

[Duncan Coutts]

On Fri, 2007-10-26 at 23:13 -0700, Conal Elliott wrote:
> I'd like libraries to provide QuickCheck support (instances of
> Arbitrary) for types they define, where possible.  Are there any
> reasons not to routinely do so?  Otherwise, I end up working them out
> for myself and probably replicating other people's work. 

People sometimes worry about making their packages depend on the
QuickCheck package.

For example QuickCheck is not required to build ghc, but if we included
the Arbitrary instances for ByteString in the bytestring package then
ghc would depend on QuickCheck.

Perhaps one solution is to use configurations, so people can build a
package with or without the QuickCheck dependency.

Duncan