Ord TermIdentifier changed

src/Foundation.hs

@@ -267,6 +267,7 @@ isAuthenticated = do
         Nothing -> Unauthorized "You must login to access this page"
         Just _ -> Authorized
 
+
 instance YesodAuthPersist UniWorX
 
 -- This instance is required to use forms. You can modify renderMessage to

src/Handler/Term.hs

@@ -22,6 +22,7 @@ getShowTermsR = do
     setTitle "Freigeschaltete Semester"
     -- TODO: provide common utility function for formatting Times
     -- TODO: turn into proper table
+    -- TODO Edit-Links only $if isAdmin, otherwise breadcrumb navigation
     [whamlet|
       <h2>
         Liste der freigeschalteten Semester:

src/Model/Types.hs

@@ -56,7 +56,7 @@ seasonFromChar c
 data TermIdentifier = TermIdentifier
   { year :: Integer -- ^ Using 'Integer' to model years is consistent with 'Data.Time.Calendar'
   , season :: Season
-  } deriving (Show, Read, Eq, Ord, Generic, Typeable)
+  } deriving (Show, Read, Eq, Generic, Typeable)
 
 --TODO: Enforce the number of digits within year, with parsing filling in the current leading digits? Goal: short urls
 termToText :: TermIdentifier -> Text
@@ -70,6 +70,11 @@ termFromText t
   = Right TermIdentifier{..}
   | otherwise = Left $ "Invalid TermIdentifier: “" <> t <> "”"
 
+instance Ord TermIdentifier where
+  ti1 <= ti2 =
+    year ti1 <= year ti2 || 
+    (year ti1 == year ti2 || season ti1 <= season ti2)
+  
 instance PersistField TermIdentifier where
   toPersistValue = PersistText . termToText
   fromPersistValue (PersistText t) = termFromText t