Assertions are very useful to catch logical errors in the code during development, but they impose a runtime overhead that you may like to avoid in the production environment. Since assert is a compile time variable, the assertions can be silenced either by binding assert to false or by using alter-var-root before the code is loaded. Unfortunately, both the techniques are cumbersome to use. Paul Stadig's library called assertions (https://github.com/pjstadig/assertions) helps with this exact use-case by enabling or disabling assertions via the command-line argument -ea to the Java runtime.

To use it, you must include it in your Leiningen project.clj file as a dependency:

:dependencies [;; other dependencies…
                            [pjstadig/assertions...