Fix deployment build

src/Handler/Course.hs

@@ -7,7 +7,6 @@
 {-# LANGUAGE MultiParamTypeClasses #-}
 {-# LANGUAGE TypeFamilies #-}
 {-# LANGUAGE FlexibleContexts #-}
-{-# LANGUAGE OverloadedLists #-}
 
 module Handler.Course where
 
@@ -19,6 +18,8 @@ import qualified Data.Text as T
 import Data.Function ((&))
 -- import Yesod.Form.Bootstrap3
 
+import qualified Data.Map as Map
+
 import Colonnade hiding (fromMaybe,bool)
 -- import Yesod.Colonnade
 
@@ -67,7 +68,8 @@ getTermCourseListR tid = do
             Nothing -> MsgCourseMembersCount num
             Just max -> MsgCourseMembersCountLimited num max
         ]
-    , dbtSorting = [ ( "shorthand"
+    , dbtSorting = Map.fromList
+        [ ( "shorthand"
           , SortColumn $ \course -> course E.^. CourseShorthand
           )
         , ( "register-from"
@@ -82,7 +84,7 @@ getTermCourseListR tid = do
               return (E.countRows :: E.SqlExpr (E.Value Int64))
           )
         ]
-    , dbtFilter = []
+    , dbtFilter = mempty
     , dbtAttrs = tableDefault
     , dbtIdent = "courses" :: Text
     }