Mapping from IO type to a "pure" type

supress.hs

-- we can define functions that discard IO

io :: IO Int
io = print "wehaa" >> return 17

supress :: IO Int -> Int
supress _ = 42

supress io

-- I don't think there is a way to preserve the 
-- integer returned in io in supress
-- after all it could be read from a file etc.