No Arbitrary instances for fixed size integrals

[Alexey Khudyakov]

Hello

Recently I learned that fixed size integral types like Int8,Word8...
do not have Arbitrary instance. That's annoying when one need to work 
with these types. So could you add such instances?

I wasn't able to find QuickCheck repository so I paste code for 
instances inline instead of proper patch:




import Data.Word (Word8,Word16,Word32,Word64)
import Data.Int  (Int8, Int16, Int32, Int64 )

instance Arbitrary Int8 where
   arbitrary = arbitraryBoundedIntegral
instance Arbitrary Int16 where
   arbitrary = arbitraryBoundedIntegral
instance Arbitrary Int32 where
   arbitrary = arbitraryBoundedIntegral
instance Arbitrary Int64 where
   arbitrary = arbitraryBoundedIntegral
instance Arbitrary Word8 where
   arbitrary = arbitraryBoundedIntegral
instance Arbitrary Word16 where
   arbitrary = arbitraryBoundedIntegral
instance Arbitrary Word32 where
   arbitrary = arbitraryBoundedIntegral
instance Arbitrary Word64 where
   arbitrary = arbitraryBoundedIntegral