* lib.c (acons): New function.

(set_diff): Optimize common case: list1 and list2
are the same, or list2 is substructure of list1.
Situations in which this won't be the case for variable bindings are
rare.

* lib.h (acons): Declared.

* match.c (match_line): Use acons rather than acons_new, when binding
variables that we know are new (the symbol is unbound).
When computing the set difference over bindings, use cons cell
equality, rather than symbol equality. Symbol equality is wrong
because a binding can be removed, and then a new binding can be
introduced using the same symbol. This must be treated as
a different binding.

0 files changed, 0 insertions, 0 deletions