clojure/clojure — pull request #41 by nickgieschen (2013-08-25 22:02:57+00:00)
Title: Make mapcat not indicate that it can accept a variable number of colls

The signature indicates that (mapcat #(list (inc %)) [1 2 3] [4 5 6]) should be okay. However, it throws a ArityException since under the hood it's doing (apply map #(list (inc %)) '([1 2 3] '[4 5 6])).