Clojure :: arity-overloaded functions calling each other -

Clojure :: arity-overloaded functions calling each other -

examples of clojure arity-overloading on functions next (taken cookbook):

(defn argcount ([] 0) ; 0 arguments ([x] 1) ; 1 argument ([ x & args] (inc (count args)))) ; list of arguments

... utilize form doesn't seem allow functions of lower arity phone call functions of higher arity default values (that's mutual idiom in java). other special form used ?

there's way express higher arity arguments in way doesn't need refer other arities using higher order functions , map / reduce. in case it's pretty simple:

(defn argcount ([] 0) ([x] 1) ([x & args] (reduce + 1 (map (constantly 1) args))))

notice general form of look is:

(reduce reducing-function arity-1-value (map mapping-function rest-of-args))

you can't way, works surprisingly big proportion of multi-argument functions. gains advnatages of laziness using map, can crazy things pass 10 1000000 arguments function little fear:

(apply argcount (take 10000000 (range))) => 10000000

try in other languages , stack toast :-)

clojure