deque-blog

deque-blog / rapid_check_overflow_detection.hs

Last active February 5, 2017 16:58

	instance Arbitrary Int where
	arbitrary = Gen $ \rand -> fst (next rand)

	prop_gcd_overflow :: Int -> Int -> Bool
	prop_gcd_overflow a b = a * b == gcd a b * lcm a b

	rapidCheck prop_gcd_overflow
	> Failure {seed = -881134321,
	counterExample = ["171542757","1235104953"]}

deque-blog / rapid_check_example_testable.hs

Created February 2, 2017 21:48

	prop_gcd :: Integer -> Integer -> Bool
	prop_gcd a b = a * b == gcd a b * lcm a b

deque-blog / rapid_check_2_prop_partition.hs

Last active February 4, 2017 15:03

	prop_partition :: [Integer] -> (Integer -> Bool) -> Bool
	prop_partition xs p =
	let (lhs, rhs) = partition p xs
	in and
	[ all p lhs
	, not (any p rhs)
	, sort xs == sort (lhs ++ rhs) ]

	rapidCheck prop_partition
	> Success

deque-blog / rapid_check_2_prop_distributive.hs

Last active February 5, 2017 14:27

	prop_distributive :: Integer -> Integer -> (Integer -> Integer) -> Bool
	prop_distributive a b f = f (a + b) == f a + f b

	rapidCheck prop_distributive
	> Failure {seed = 7720540227186278723,
	counterExample = ["1716301762","55093645","<function>"]}

deque-blog / rapid_check_2_promote.hs

Created February 4, 2017 15:20

deque-blog / rapid_check_2_coarbitrary.hs

Last active February 4, 2017 15:51

	class CoArbitrary a where
	coarbitrary :: Gen b -> a -> Gen b

deque-blog / rapid_check_2_arbitrary_function.hs

Created February 4, 2017 15:51

	instance
	(CoArbitrary a, Arbitrary b)
	=> Arbitrary (a -> b)
	where
	arbitrary = promote (coarbitrary arbitrary)

deque-blog / rapid_check_2_coarbitrary_integer.hs

Created February 4, 2017 16:21

	instance CoArbitrary Integer where
	coarbitrary gen n =
	Gen $ \rand ->
	runGen gen (perturb n rand)

deque-blog / rapid_check_2_perturb.hs

Last active February 4, 2017 17:23

	perturb :: (Integral n) => n -> StdGen -> StdGen
	perturb n rand0 =
	foldl
	(\rand b -> vary b rand) -- Vary generator based on digit value
	(vary (n < 0) rand0) -- Vary generator based on sign
	(digits (abs n)) -- Decompose a positive number in digits
	where
	vary digit rand =
	(if digit then snd else fst)
	(split rand)

deque-blog / rapid_check_2_coarbitrary_list_int.hs

Created February 4, 2017 17:51

	instance CoArbitrary [Int] where
	coarbitrary gen xs =
	Gen $ \rand ->
	runGen gen (foldr perturb (perturb 0 rand) xs)