There's no disaster as far as I know. This is a old, well understood Lisp idiom. Clojure specifically has a ton of macros, functions and patterns around this co

There's no disaster as far as I know. This is a old, well understood Lisp idiom. Clojure specifically has a ton of macros, functions and patterns around this concept, such as if-let, when-let, some->, looking up stuff in a map, just to name a few, much this goes under the umbrella of "nil-punning" and "logically true values" etc. Caveats and boundaries: It is typically clear whether something can return a nil or accepts a nil value one versus when it doesn't. A good example would be string methods and other Java interop, where you will make sure you don't pass in a nil value, you are crossing language boundaries here so to speak. Another boundary of nil usage would be sequences, which will not evaluate to falsy, even if empty, so you explicitly would call seq or empty? on them. The bottom line is that you are very aware of nil values and their falsiness in Clojure and that you program with them rather than against them.