cga/QueueEx.hs
2014-10-26 04:29:49 +01:00

24 lines
695 B
Haskell

module QueueEx where
import Control.Applicative
import Data.Dequeue (BankersDequeue)
import qualified Data.Dequeue as Q
import Data.Maybe
-- |Shift a queue to the left, such as:
-- [1, 2, 3] -> [2, 3, 1]
shiftQueueLeft :: BankersDequeue a -> BankersDequeue a
shiftQueueLeft = (\(b, nq) -> Q.pushBack nq (fromJust b)) <$> Q.popFront
-- |Shift a queue to the right, such as:
-- [1, 2, 3] -> [3, 1, 2]
shiftQueueRight :: BankersDequeue a -> BankersDequeue a
shiftQueueRight = (\(b, nq) -> Q.pushFront nq (fromJust b)) <$> Q.popBack
-- |Convert a Queue back to a list.
queueToList :: BankersDequeue a -> [a]
queueToList q = Q.takeFront (Q.length q) q