(hons-equal-lite x y)is a non-recursive equality check that optimizes if
its arguments are normed.
Major Section: HONS-AND-MEMOIZATION
In the logic,
hons-equal-lite is just
equal; we leave it enabled and
would think it odd to ever prove a theorem about it.
Under the hood,
hons-equal-lite checks whether its arguments are normed,
and if so it effectively becomes a
eql check. Otherwise, it immediately
equal to determine if its arguments are equal.
The idea here is to strike a useful balance between
hons-equal. If both arguments happen to be normed, we get to use a very
fast equality comparison. Otherwise, we just get out of the way and let
equal do its work, without the extra overhead of recursively checking
whether the subtrees of x and y are normed.