Export code necessary to make Arbitrary instances

[treeowl]

Arbitrary instances are defined as orphans in the tests. This is reasonable, because they're tuned to test the implementations, rather than for users. However, it might be nice to export some functions designed to allow fast Arbitrary instances in QuickCheck.

[foxik]

All tests are compiled with TESTING macro, which exports constructors and several other methods, so I think the Arbitrary instances could be defined more efficiently -- it is just that no one did that :-)

Also, if you need more methods for testing, just add them to the conditionally exported list

[treeowl]

@foxik What I'm really talking about are functions to support quickcheck testing of code that uses containers. For sequences, that mostly means an efficient shrink (the one for lists is pretty ... arbitrary, so I think there's a good bit of wiggle room). For other containers, I'm not really sure.

[foxik]

Oh, sorry, I did not get that. Reopening.

[treeowl]

Thanks.

[sjakobi]

I wonder whether it would be better to discuss the Arbitrary instances on the QuickCheck issue tracker.

Here, the issue doesn't seem to get a lot of attention.