The type of keys.

The type of caches with 'a values.

create n creates a new, empty cache, with initial size n. For best results, n should be on the order of the expected number of elements that will be in the cache. The cache must grow as needed, so n is just an initial guess.

Empty a cache.

add cache key v adds a binding of key to v in cache cache.

find cache v returns the current binding of v in cache, or must raise Not_found if v is not in cache.

length cache returns the number of bindings in cache.

stats cache return statistics about the cache cache.