use year of latest update on gallery page

make-pages/GalleryPage.hs

@@ -85,7 +85,7 @@ make' root (GalleryInfo {title, desc, prefix, filters, hidden}) infos = [b|@0
     [(the year, infopath) |
       infopath@(_, info) <- infos,
       then sortOn by Down info,
-      let year = #year info,
+      let year = #latestYear info,
       then group by Down year using groupBy']
   groupBy' f = groupBy ((==) `on` f)
 

make-pages/Info.hs

@@ -114,6 +114,10 @@ instance HasField "day"   Info Int     where getField = #third  . #dmy
 instance HasField "latestDate" Info Day where
   getField (Info {date, updates}) = maximum (date : Map.keys updates)
 
+instance HasField "latestYear" Info Integer where
+  getField = #first . toGregorian . #latestDate
+
+
 instance HasField "updated" Info Bool where getField = not . Map.null . #updates
 
 descFor :: Bool -> Info -> Maybe Text