Fix build with latest dequeue

CG2.cabal

@@ -80,7 +80,7 @@ executable Gtk
                        base >=4.6,
                        bytestring >= 0.10.4.0,
                        containers >= 0.5.0.0,
-                       dequeue >= 0.1.5,
+                       dequeue >= 0.1.12,
                        diagrams-lib >=1.3,
                        diagrams-cairo >=1.3,
                        diagrams-contrib >= 1.3.0.0,
@@ -129,7 +129,7 @@ executable Gif
                        base >=4.6,
                        bytestring >= 0.10.4.0,
                        containers >= 0.5.0.0,
-                       dequeue >= 0.1.5,
+                       dequeue >= 0.1.12,
                        diagrams-lib >=1.3,
                        diagrams-cairo >=1.3,
                        diagrams-contrib >= 1.3.0.0,

QueueEx.hs

@@ -3,7 +3,6 @@ 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:
@@ -20,4 +19,4 @@ 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
+queueToList q = Q.takeFront (length q) q