This module provides a set of caching hash table functions.
Looks up id in ct. If it is not present, then mk is called to construct the value and add it to ct.
ct : cache-table? entry-ids : (or/c false/c (listof symbol?)) = #f
If entry-ids is #f, clears all entries in ct. Otherwise, clears only the entries with keys in entry-ids.
Changed in version 220.127.116.11 of package web-server-lib: Added optional argument.