LRU memoization

The least-recently-used memoization strategy is one that evicts items that are accessed least frequently once its threshold has been exceeded.

In simple terms, the LRU cache will remove the element in the cache that has not been accessed in the longest time.

General use

To create a core.memoize LRU-backed memoized function use the clojure.core.memoize/lru function with an optional seed map or a :lru/threshold parameter:

(memo/lru function <seed> <:lru/threshold number>)

Example code is as follows:

(ns your.lib
  (:require [clojure.core.memoize :as memo]))

(def memoized-fun
  (memo/lru identity {} :lru/threshold 3))

The default :lru/threshold value is 32 and refers to the number of elements in the cache required before the LRU logic is applied.

Please read the clojure.core.cache information regarding LRU caches for more detailed information, use cases and usage patterns.

As always, you should measure your system's characteristics to determine the best eviction strategy for your purposes.