+ add_lvl env (v,l) = extendVarEnv env v l
+ del_subst env (v,_) = extendInScope env v
+ del_id env (v,_) = delVarEnv env v
+ -- We must remove any clone for this variable name in case of
+ -- shadowing. This bit me in the following case
+ -- (in nofib/real/gg/Spark.hs):
+ --
+ -- case ds of wild {
+ -- ... -> case e of wild {
+ -- ... -> ... wild ...
+ -- }
+ -- }
+ --
+ -- The inside occurrence of @wild@ was being replaced with @ds@,
+ -- incorrectly, because the SubstEnv was still lying around. Ouch!
+ -- KSW 2000-07.