boot.user=> (source partial)
(defn partial
  "Takes a function f and fewer than the normal arguments to f, and
  returns a fn that takes a variable number of additional args. When
  called, the returned function calls f with args + additional args."
  {:added "1.0"
   :static true}
  ([f] f)
  ([f arg1]
   (fn
     ([] (f arg1))
     ([x] (f arg1 x))
     ([x y] (f arg1 x y))
     ([x y z] (f arg1 x y z))
     ([x y z & args] (apply f arg1 x y z args))))
  ([f arg1 arg2]
   (fn
     ([] (f arg1 arg2))
     ([x] (f arg1 arg2 x))
     ([x y] (f arg1 arg2 x y))
     ([x y z] (f arg1 arg2 x y z))
     ([x y z & args] (apply f arg1 arg2 x y z args))))
  ([f arg1 arg2 arg3]
   (fn
     ([] (f arg1 arg2 arg3))
     ([x] (f arg1 arg2 arg3 x))
     ([x y] (f arg1 arg2 arg3 x y))
     ([x y z] (f arg1 arg2 arg3 x y z))
     ([x y z & args] (apply f arg1 arg2 arg3 x y z args))))
  ([f arg1 arg2 arg3 & more]
   (fn [& args] (apply f arg1 arg2 arg3 (concat more args)))))
nil