[Simplified RatingData's compare function
tobias@goedderz.info**20150213103351
 Ignore-this: 2264b20136a328b8340213a705004d5
] hunk ./src/Igor2/Data/Rateable.hs 41
-    compare (RD a1 b1 c1 d1 _)(RD a2 b2 c2 d2 _)
-        | a1 == a2  = compare (b1,c1,d1) (b2,c2,d2)
-        | otherwise = compare a1 a2
+    compare = compare `on` \(RD a b c d _) -> (a, b, c, d)
+