On Mon, Oct 12, 2009 at 11:51:49AM +0530, Srikanth K wrote:
However, being a newbie, I am not able to understand how I can extract the "Response" part from the IO Response.
I want something as follows prop_App state_x command_y = (abstract_App state_x command_y ) == (real_App state_x command_y)
The issue here is that since the reall_App would return a "IO Response" and not "Response" I cannot really compare the abstract_App with the real_App.
Any thought on how I can extract the value from the "IO Response" so that I can compare the the two implementations for equvivalence.
Hi Srikanth, The short answer is: you can't extract a Response from an IO Response. Once something is infected with IO, there's no cure!* However, you can compare the responses if you make the result of prop_App an IO action itself: prop_App :: State -> Command -> IO Bool prop_App state_x command_y = do realResponse <- real_App state_x command_y return $ abstract_App state_x command_y == realResponse Off the top of my head I'm not sure of the proper way to run such monadic tests with QuickCheck, but it can definitely be done. -Brent * Some smart-alecks might pipe up with something about unsafePerformIO here. But that's not a cure, it's more like performing an emergency tracheotomy with a ballpoint pen.