`(hons-equal x y)`

is a recursive equality check that optimizes when parts of
` `

its arguments are normed.
Major Section: HONS-AND-MEMOIZATION

This documentation topic relates to the experimental extension of ACL2 supporting hash cons, fast alists, and memoization; see hons-and-memoization.

In the logic, `hons-equal`

is just `equal`

; we leave it enabled and would
think it odd to ever prove a theorem about it.

Under the hood, when `hons-equal`

encounters two arguments that are both
normed, it becomes a mere `eql`

check, and hence avoids the overhead of
recursively checking large cons structures for equality.

Note. If `hons-equal`

is given arguments that do not contain many normed
objects, it can actually be much slower than `equal`

! This is because it
checks to see whether its arguments are normed at each recursive step, and so
you are repeatedly paying the price of such checks. Also see hons-equal-lite,
which only checks at the top level whether its arguments are normed.