Average.hs

import Control.Monad.State

type Count = Int
--type Sum = Int
type MyState = State Count

n :: Float -> Float -> MyState Float
n x s = do 
            c <- get
            let c' = c+1
            put c'
            return $ (x+s)

end :: Float -> MyState Float
end s = do
          c <- get
          return $ s / (fromIntegral c :: Float)

fun = (return 0.0) >>= (n 3.0) >>= (n 4.0) >>= (n 5.0) >>= (n 6.0) >>= end
avg = runState fun 0

main = print $ avg