[avoid O(n^2) in Igor2.Ppr.patternNotDef
Helmut Grohne <grohne@cs.uni-bonn.de>**20150108152843
 Ignore-this: 1b68a351f4e3a6a5468ae9fbeb65cc89
] hunk ./src/Igor2/Ppr.hs 36
-                   vsep [ text "arg" <> int (i+1) <+> (as !! i) | i <- [0 .. (length as)-1]]
+                   vsep [ text "arg" <> int i <+> a | (a, i) <- zip as [1..]]