Skip to content


Switch branches/tags

Latest commit


Git stats


Failed to load latest commit information.
Latest commit message
Commit time


core.memoize is a Clojure contrib library providing the following features:

  • An underlying PluggableMemoization protocol that allows the use of customizable and swappable memoization caches that adhere to the synchronous CacheProtocol found in core.cache

  • Memoization builders for implementations of common caching strategies, including:

    • First-in-first-out (clojure.core.memoize/fifo)
    • Least-recently-used (clojure.core.memoize/lru)
    • Least-used (clojure.core.memoize/lu)
    • Time-to-live (clojure.core.memoize/ttl)
    • Naive cache (memo) that duplicates the functionality of Clojure's memoize function but, unlike the built-in memoize function, ensures that in the case of concurrent calls with the same arguments, the memoized function is only invoked once; in addition memo can use metadata from the memoized function to ignore certain arguments for the purpose of creating the cache key, e.g., allowing you to memoize functions where the first argument includes a (mutable) JDBC Connection object by specifying :clojure.core.memoize/args-fn rest in the metadata
  • Functions for manipulating the memoization cache of core.memoize backed functions

Releases and Dependency Information

This project follows the version scheme MAJOR.MINOR.COMMITS where MAJOR and MINOR provide some relative indication of the size of the change, but do not follow semantic versioning. In general, all changes endeavor to be non-breaking (by moving to new names rather than by breaking existing names). COMMITS is an ever-increasing counter of commits since the beginning of this repository.

Latest stable release: 1.0.257

CLI/deps.edn dependency information:

org.clojure/core.memoize {:mvn/version "1.0.257"}

Leiningen dependency information:

[org.clojure/core.memoize "1.0.257"]

Maven dependency information:


Example Usage

      (:require clojure.core.memoize))

    (def id (clojure.core.memoize/lu
	          #(do (Thread/sleep 5000) (identity %))
			  :lu/threshold 3))

    (id 42)
    ; ... waits 5 seconds
    ;=> 42

    (id 42)
    ; instantly
    ;=> 42

Refer to docstrings in the clojure.core.memoize namespace for more information.

Developer Information

Change Log

  • Release 1.0.257 on 2022.02.11
    • Implement IPending for RetryingDelay for folks trying to do low-level availability tests on long-running memoized functions.
  • Release 1.0.253 on 2021.12.06
    • Update core.cache to 1.0.225
  • Release 1.0.250 on 2021.08.02
    • Clarify differences between clojure.core/memoize and clojure.core.memoize/memo functions CMEMOIZE-25.
    • Update core.cache to 1.0.217.
  • Release 1.0.236 on 2020.04.13
    • Switch to 1.0.x versioning CMEMOIZE-29.
    • Update core.cache dependency version from 0.8.2 to 1.0.207.
    • Fixes CMEMOIZE-9 - adds memo-reset! and deprecates 2-arity version of memo-swap!; adds 3+-arity version of memo-swap! to behave more like a swap! operation on the underlying cache
  • Release 0.8.2 on 2019.11.01 (to match core.cache again)
    • Update core.cache dependency version from 0.7.2 to 0.8.2.
    • Fixes CMEMOIZE-28 - provides memoizer as a more convenient way to build custom cached functions that may provide a seed hash map of arguments to return values. build-memoizer should be considered deprecated at this point.
    • Fixes CMEMOIZE-27 - the seed function on PluggableMemoization now makes elements derefable (this case was missed when CMEMOIZE-18 was fixed)
  • Release 0.7.2 on 2019.06.13
    • Fixes CMEMOIZE-26 - zero-arity function cache could not be replaced by memo-swap! (discovered by Teemu Kaukoranta)
    • Updated core.cache dependency version from 0.7.1 to 0.7.2
    • Updated test matrix locally to include Clojure 1.10.1, 1.11 master
  • Release 0.7.1 on 2018.03.02
    • Fixes CMEMOIZE-15 - edge case where cache miss/lookup cross an eviction boundary (Ryan Fowler/Colin Jones)
    • Updated core.cache dependency version from 0.7.0 to 0.7.1 (for TTLCacheQ bug fix)
  • Release 0.7.0 on 2018.03.01
    • Fixes CMEMOIZE-22 - add :clojure.core.memoize/args-fn metadata support for memoizing functions which have one or more arguments that should not contribute to the cache key for calls
    • Fixes CMEMOIZE-20 - add lazy-snapshot function
    • Fixes CMEMOIZE-18 - automatically makes seed map values deref-able to match documentation and comply with core.memoize's world view
    • Cleanup/improve/fix tests
    • Add multi-version testing locally via Leiningen
    • Jump to 0.7.0 to match core.cache since these two libraries are so closely in sync
  • Release 0.5.9 on 2016.03.28
    • Updated core.cache dependency version from 0.6.4 to 0.6.5
  • Release 0.5.8 on 2015.11.06
  • Release 0.5.7 on 2015.01.12
  • Release 0.5.6 on 2013.06.28
    • Added optional args to memo-clear!.
    • Widened contract on factory functions to accept any callable.
  • Release 0.5.5 on 2013.06.14
    • Deprecated memo-* APIs
    • Adds new API of form (cache-type function <base><:cache-type/threshold int>)
  • Release 0.5.4 on 2013.06.03
  • Release 0.5.3 on 2013.03.18
    • Works with core.cache v0.6.3
  • Release 0.5.2 on 2012.07.13
    • Works with core.cache v0.6.1
  • Release 0.5.1 on 2011.12.13
    • Removed SoftCache memoization
  • Release 0.5.0 on 2011.12.13
    • Rolled in basis of Unk

Copyright and License

Copyright (c) Rich Hickey and Michael Fogus, 2012, 2013. All rights reserved. The use and distribution terms for this software are covered by the Eclipse Public License 1.0 ( which can be found in the file epl-v10.html at the root of this distribution. By using this software in any fashion, you are agreeing to be bound bythe terms of this license. You must not remove this notice, or any other, from this software.


A manipulable, pluggable, memoization framework for Clojure







No packages published