Lab 3: Ex 4

[BertLisser]

genCnj :: Int -> Gen Form
genCnj i = do n <- choose(2, i)
              f <- vectorOf n (genForm (i `div` n))
return (Cnj f)

Too complicated and to restricted. Simpler solution by using n of sized.
So an improvment will be

genCnj :: Int -> Gen Form
genCnj n = do 
              f <- vectorOf n (genForm (n `div` 2))
return (Cnj f)

And

-- Exercise 4 - Erik van Scharrenburg
instance Arbitrary Form where
  arbitrary = sized genForm

genForm :: Int -> Gen Form
genForm 0 = genProp
genForm 1 = genProp
genForm 2 = genProp
genForm i = oneof [genNeg   (i - 1),
                   genCnj   (i - 1),
                   genDsj   (i - 1),
                   genImpl  (i - 1),
                   genEquiv (i - 1)]

genProp :: Gen Form

Better

-- Exercise 4 - Erik van Scharrenburg
instance Arbitrary Form where
  arbitrary = sized genForm

genForm :: Int -> Gen Form
genForm 0 = genProp
genForm n = oneof [genNeg   n
                   genCnj   n,
                   genDsj   n,
                   genImpl  n,
                   genEquiv n]

genProp :: Gen Form

Well done (=9)