A straightforward addition for the existing interface to the underlying cache. Useful for cases where the memoization cache need only be evicted for some inputs.

Please let me know if this is not the desired channel or format for submissions!

I believe this line https://github.com/clojure/core.memoize/blob/9bdf608af8bbf4a753fc19758446dd821cb45979/src/main/clojure/clojure/core/memoize.clj#L72 assumes too much about implementations of CacheProtocol, namely that they have a field named 'cache'.

The first call to .cache makes sense, since PluggableMemoization has a 'cache' field, but the second call to .cache assumes that any implementation of CacheProtocol that PluggableMemoization wraps will have a 'cache' field.

I ran into this issue when I desired to have a cache that ignores nils, so I attempted to wrap the TTLCache with an implementation of CacheProtocol that would not cache nil values. Calls to snapshot failed since it was trying to access a 'cache' field on my NoNilCache.

I suspect that the outer call to .cache could be replaced with a call to seq, since defcache adds an implementation of seq to each cache implementation which should pull out the keys/values from the cache.

I'd be glad to work up a patch given that I'm not off base in my assumptions.

core.memoize was originally Unk , but its inclusion into contrib means the latter is redundant. The Unk repo should indicate the move and change to a place for docs and examples. Likewise, a formal announcement should be made.

The core.memoize functionality is inline with Unk. A release should be cut and pushed to Maven central.