shiftL package:deque

shiftLeft :: Deque a -> Deque a
deque Deque.Lazy Deque.Strict
, occasionally <math>. Move the first element to the end. 
λ toList . shiftLeft $ fromList [1,2,3]
[2,3,1]
shiftLeft :: MonadReader (Deque a) m => m (Deque a)
deque Deque.Lazy.Reader Deque.Strict.Reader
, occasionally <math>. Move the first element to the end.
shiftLeft :: MonadState (Deque a) m => m ()
deque Deque.Lazy.State Deque.Strict.State
, occasionally <math>. Move the first element to the end.