[Haskell-cafe] QuickCheck Questions

[Mark Spezzano]

Hi all,

I would appreciate it if someone can point me in the right direction with the following problem.

I'm deliberately implementing a naive Queues packages that uses finite lists as the underlying representation. I've already read through Hughes' paper and the article in The Fun of Programming, but I'm still having some difficulties. Specifically:

1. I have a newtype Queue a = Queue [a] and I want to generate Queues of random Integers that are also of random size. How do I do this in QuickCheck? I guess that  I need to write a generator and then make my "Queue a" concrete type an instance of Arbitrary? How?

2. If I wanted to specify/constrain the ranges of random Integers generated, how would I do this?

3. If I wanted to specify/constrain the Queue sizes how would I do this?

On a separate issue, I also see that QuickCheck 2 has some features not discussed anywhere. For example "Coarbitrary" and "shrink" are a bit of a mystery to me.

Any code examples for any of the above questions would help greatly.

I've been stuck on this problem for hours. :)

Cheers,

Mark