[handle negative patterns of literals, produce error on other uses of negative patterns
John Meacham <john@repetae.net>**20061212053117] hunk ./FrontEnd/Tc/Main.hs 418
+tiPat (HsPNeg (HsPLit (HsInt i))) typ = tiPat (HsPLit $ HsInt (negate i)) typ
+tiPat (HsPNeg (HsPLit (HsFrac i))) typ = tiPat (HsPLit $ HsFrac (negate i)) typ
+tiPat (HsPNeg (HsPLit (HsIntPrim i))) typ = tiPat (HsPLit $ HsIntPrim (negate i)) typ
+tiPat (HsPNeg (HsPLit (HsFloatPrim i))) typ = tiPat (HsPLit $ HsFloatPrim (negate i)) typ
+tiPat (HsPNeg (HsPLit (HsDoublePrim i))) typ = tiPat (HsPLit $ HsDoublePrim (negate i)) typ
+tiPat (HsPNeg pat) typ = fail $ "non-literal negative patterns are not allowed"