Skip to content


Repository files navigation


Contracts programming for Clojure.

Project status: Inactive. The author (fogus) considers this library to have been superseded by clojure.spec.

Based on Trammel and clojure-contracts.

Releases and Dependency Information

Latest stable release: 0.0.6

CLI/deps.edn dependency information:

org.clojure/core.contracts {:mvn/version "0.0.6"}

Leiningen dependency information:

[org.clojure/core.contracts "0.0.6"]

Maven dependency information:


Example Usage

    (use 'clojure.core.contracts)
	(def secure-doubler
	  	(fn [n] (* 2 n))
	  	(contract doubler
          "ensures doubling"
          [x] [number? => (= (* 2 x) %)]
          [x y] [(every? number? [x y])
                 (= (* 2 (+ x y)) %)])))

    (secure-doubler 10)
    ;=> 20

Refer to docstrings in the clojure.core.contracts namespace.


core.contracts API

See also the wiki for some documentation and examples.

Developer Information

Change Log

  • Release 0.0.6 on 2016.08.20
    • Bump dependency on newest version of core.unify, which fixes a compilation problem with Clojure 1.9.0-alpha11
  • Release 0.0.5 on 2013.06.28
    • Speedier constrained record perf.
  • Release 0.0.4 on 2013.03.07
    • Rolled in defconstrainedrecord
    • Rolled in associative checks
  • Release 0.0.1 on 2012.06.01
    • Rolled in contract, with-constraints and provide from Trammel

Copyright and License

Copyright (c) Rich Hickey, Michael Fogus and contributors, 2023. 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.