If one initializes an LRU or LU cache with seed data and those datum are never touched, then they are never evicted.

  (def C (lru-cache-factory {:a 1, :b 2} :limit 2))
  
  (-> C (assoc :c 3) (assoc :d 4) (assoc :e 5))

You would expect that the cache should contain only :d and :e, but it instead includes :a, :b, :d and :e! The problem is that seeds are never added to the eviction queue.

Currently, lookup comes in only the 2-arg flavor (i.e. gimme a key and I'll give you a value or nil). The issue with this is that nil is potentially a legal value. Therefore, the 3-arg version logic is the same as the 3-arg `assoc` (.lookup this key not-found).

This change should propagate to all of the existing cache impls.

A cache implementation that is backed by a function that performs some action on a cache miss could serve as a front for any of the existing cache impls.

Perform some tests and benchmarks of core.cache and Google Guava's com.google.common.cache library.

The evict method in the ProtocolCache needs implementation for LIRSCache. I will start initially with a single key eviction method to start. The evict method would form the basis for the associative dissoc which in turn forms the basis for proper limited seeding. LIRS poses an additional complication due to its dual limit lists. Currently only the BasicCache impl has evict.

The evict method in the ProtocolCache needs implementation for LUCache. I will start initially with a single key eviction method to start. The evict method would form the basis for the associative dissoc which in turn forms the basis for proper limited seeding. Currently only the BasicCache impl has evict.

The evict method in the ProtocolCache needs implementation for LRUCache. I will start initially with a single key eviction method to start. The evict method would form the basis for the associative dissoc which in turn forms the basis for proper limited seeding. Currently only the BasicCache impl has evict.

The evict method in the ProtocolCache needs implementation for FIFOCache. I will start initially with a single key eviction method to start. The evict method would form the basis for the associative dissoc which in turn forms the basis for proper limited seeding. Currently only the BasicCache impl has evict.

LIRS is implemented as a type only ATM. There should also be a corresponding factory fn.

Clache had an implementation of the LIRS http://citeseer.ist.psu.edu/viewdoc/summary?doi=10.1.1.116.2184 strategy. This capability should be merged into core.cache also.