cga/QueueEx.hs

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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
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shiftQueueLeft = (\(Just (b, nq)) -> Q.pushBack nq b) <$> Q.popFront
-- |Shift a queue to the right, such as:
-- [1, 2, 3] -> [3, 1, 2]
shiftQueueRight :: BankersDequeue a -> BankersDequeue a
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shiftQueueRight = (\(Just (b, nq)) -> Q.pushFront nq b) <$> Q.popBack
-- |Convert a Queue back to a list.
queueToList :: BankersDequeue a -> [a]
queueToList q = Q.takeFront (Q.length q) q