While we're talking about quickcheck, I noticed that the "vector" function mentioned in the manual is inconsistent with the one in the libraries: The manual [1] claims: Useful Generator Combinators If g is a generator for type t, then * two g generates a pair of ts, * three g generates a triple of ts, * four g generates a quadruple of ts, * vector n g generates a list of n ts. ... Whereas the type is actually: vector :: Arbitrary a => Int -> Gen [a] BTW, Martin's suggestion (defaultConfig) is useful for when I want to use "check" to run a particular number of tests (say 200 instead of the default 100) but I don't want to bother changing the other sensible values. peace, isaac [1] http://www.math.chalmers.se/~rjmh/QuickCheck/manual.html