Flens – Runtime Verification for Clojure

Flens is a runtime verification framework written in the Clojure programming language. Flens is an acronym for "Functional logic evaluation and notification system". With Flens assistance it is possible to specify correctness properties for Clojure programs which are checked at runtime. From a user’s point of view, Flens thus consists of two major functional components

  • The evaluation component: Flens checks whether or not a run of a program satisfies a given correctness property.
  • The notification component: Information about a run of a program can be generated, such as function calls or variable changes.

Flens can be downloaded here:


(Text was taken from Christian Pohlmann's master thesis)