A list monad transformer / a monadic list.

Monadic list example: A program which reads numbers from the user and accumulates them.

 import Control.Monad.Trans.List.Funcs (repeatM)
 import Data.List.Class (execute, scanl, takeWhile, mapL)
 import Prelude hiding (scanl, takeWhile)
 
 main =
     execute . mapL print .
     scanl (+) 0 .
     fmap (fst . head) .
     takeWhile (not . null) .
     fmap reads $ repeatM getLine