Comments

[BertLisser]

The 4 properties which must be tested must be:
Ex. 3

• x>3 && even x
• x>3 || even x
• even x && x>3 || even x
• even x

Ex. 4
doTestPermutation = testR 1 100 doPermutation isPermutation
In this test returns isPermutation always true. The test must also generate non permutations.

Ex.5
testDeran = quickCheckResult (\xs -> length xs <= 5 --> (foldr (&&) True $ map (isDerangement xs) (deranI xs)))
can be chenged into
testDeran = quickCheckResult (\xs -> length xs <= 5 --> (foldr (&&) True $ map (isDerangement xs) (deran xs)))::[Int]->Bool
Then you don't need to define deranI