On 7 October 2015 at 19:25, Rogan Creswick <creswick@gmail.com> wrote:

Then I'd suggest using the quickcheck property guards ( `==>`) to only
generate inputs that are known to be equal, or not equal and test
separately in a few different properties.

This is not true, ==> still does generate and test.

Prelude> import Test.QuickCheck

Prelude Test.QuickCheck> let f x = x == 13 ==> mod x 2 == 1

Prelude Test.QuickCheck> quickCheck f

*** Gave up! Passed only 6 tests.

Also try verboseCheck to see what values are generated.

Ozgur