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