Memoization code -- not re-entrant!
val general : ?hashable:'a Std_internal.Hashtbl.Hashable.t ->
?cache_size_bound:int -> ('a -> 'b) -> 'a -> 'b
Returns memoized version of any function with a single argument. The default caching policy is to remember everything for the lifetime of the returned closure, but one may specify an upper bound on cache size. Whenever a cache entry must be forgotten in order to obey this bound, we pick the least-recently-used one.
val unit : (unit -> 'a) -> unit -> 'a
efficient special case for argument type unit