make cubicaltt compile with the latest version of GHC

diff --git a/CTT.hs b/CTT.hs
index 3bc9e4cdd64f9bbe5a6586df3385623cd52f5609..21f8e9f705bc8bf2b0592ae65ceb7b6e98411d4f 100644 (file)
--- a/CTT.hs
+++ b/CTT.hs
@@ -9,6 +9,7 @@ import qualified Data.Map as Map
 import Text.PrettyPrint as PP
 import Data.Set (Set)
 import qualified Data.Set as Set
+import Prelude hiding ((<>))
 
 import Connections