Managing Web App Modes with Fun-Map in Clojure

[Fun-map](https://github.com/robertluo/fun-map) turns a Clojure map into an associative dependency injection system: the system is a map, components are entries, and each runtime mode is an `assoc` (or `dissoc`) on the base map. This article grows a minimal blog API with Datahike and http-kit from hardcoded values to three modes (prod, dev, test) with no mode conditional inside any component, and…