+ hash = hashExpr expr
+ combine old new
+ = WARN( result `lengthExceeds` 4, short_msg $$ nest 2 long_msg ) result
+ where
+ result = new ++ old
+ short_msg = ptext SLIT("extendCSEnv: long list, length") <+> int (length result)
+ long_msg | opt_PprStyle_Debug = (text "hash code" <+> text (show hash)) $$ ppr result
+ | otherwise = empty