GHC warns about non-exhaustive pattern match of Word8
import Data.Word
foo :: Word8 -> Bool
foo 0x00 = True
foo 0x01 = True
foo 0x02 = True
foo 0x03 = True
...
foo 0xFF = True
Is exhaustive, one can test that with
test = map foo [ minBound .. maxBound ]
However, GHC seems to disagree an issues a warning.
Complete file is in attachment.