import Type ( isUnLiftedType, coreEqType, splitTyConApp_maybe )
import Coercion ( coercionKind )
import CoreLint ( showPass, endPass )
-import Util ( mapAndUnzip, mapAccumL, mapAccumR, lengthIs )
+import Util ( mapAndUnzip, lengthIs )
import BasicTypes ( Arity, TopLevelFlag(..), isTopLevel, isNeverActive,
RecFlag(..), isRec )
import Maybes ( orElse, expectJust )
import Outputable
+
+import Data.List
\end{code}
To think about