This is a companion post to my discussion with Craig Andera on Relevance Podcast Episode 32 and my Clojure/West talk Clojure in the Large. I've talked about various bits and pieces of this workflow at other times, too, but I'll try to bring it all together here in the hopes that others will find it useful.

One of the great pleasures of working with a dynamic language is being able to build a system while simultaneously interacting with it. To make this possible, first you need the ability to redefine parts of the program while it is running: Clojure provides this capability admirably. However, some aspects of Clojure's runtime are not quite as late-binding as one might wish for interactive development. For example, the effect of a changed macro definition will not be seen until code which uses the macro has been recompiled. Changes to methods of a defrecord or deftype will not have any effect on existing instances of that type.