Can't compile with 7.6.3 without -XRankNTypes

[osa1]

MiniKanrenT is failing to compile with GHC 7.6.3. It requires RankNTypes to be enabled while compiling Control/Monad/LogicVarT.hs.

Adding RankNTypes to LANGUAGE pragma works.

diff --git a/src/Control/Monad/LogicVarT.hs b/src/Control/Monad/LogicVarT.hs
index 0d765aa..4a46675 100644
--- a/src/Control/Monad/LogicVarT.hs
+++ b/src/Control/Monad/LogicVarT.hs
@@ -1,5 +1,6 @@
 {-#Language GeneralizedNewtypeDeriving
-          , DeriveDataTypeable #-}
+          , DeriveDataTypeable
+          , RankNTypes #-}
 module Control.Monad.LogicVarT 
   ( LogicVarT
   , LVar, lvarKey, lvarValue