[Haskell-beginners] wierd quickcheck outcome

[Roelof Wobben]

Hello,

I have this function :

fourDifferent:: Integer -> Integer -> Integer -> Integer -> Bool
fourDifferent a b c d = ( a == b ) && ( a == c ) && (a == d)

which I wants to test with this function :

prop_fourDifferent :: Integer -> Integer -> Integer -> Integer -> Bool
prop_fourDifferent a b c d = fourDifferent a b c d == ( a == b ) && ( a 
== c ) && (a == d)

so I do quickCheck propFourDifferent and see this outcome :

*Solution> quickCheck prop_fourDifferent
*** Failed! Falsifiable (after 2 tests and 2 shrinks):
0
0
0
1

*Solution> fourDifferent 0 0 0 1
False
*Solution> let a = 0
*Solution> let b = 0
*Solution> let c = 0
*Solution> let d = 1
*Solution> (a == b) && ( a == c) && ( a == d ) False
*Solution>


So why is it failing. both gives false ,

Roelof