[perform constant case matching on EPi terms
John Meacham <john@repetae.net>**20070307140309] hunk ./E/SSimplify.hs 43
+import Name.Names
hunk ./E/SSimplify.hs 570
+            doCase (EPi TVr { tvrType = x} y) t b as d = doConstCase cont litCons { litName = tc_Arrow, litArgs = [x,y], litType = eStar} t b as d