example: data A = A INt | B [A]
instace Arbitrary A where arbitrary = oneof [ liftM A arbitrary , liftM B arbitrary ] But now QuickCheck will propably create a test value A ( B [ A ( B [ A .... -> no end Is there an easy QuickCheck way to prevent this? I can think of: a) using sized to pass when to stop (decrement the value ..) b) using some type hackary data Recursive a = R a then use arbitrary :: R ( R ( a )) and remove one R each time.. c) pass a recursion indicator manually and decrement that... Which would you choose? Marc _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe