defnk
once resided in clojure-contrib, but didn't make the jump into a new package when clojure-contrib was splitted up into multiple packages.
Instead of defnk
you could use :keys
/:or
yourself to create default values for your function arguments, so
(defnk f [:b 43] (inc b))
becomes
(defn f [& {:keys [b] :or {b 1}}] (inc b))
If you don't like it this way, nothing stops you from taking the source of defnk
and use it yourself.