Testing arity vs map function call speed in clojure

arity-vs-map-args.clj

(defn add [x y] (+ x y))=> #'user/add(defn addm [{x :x y :y}] (+ x y))=> #'user/addm(reduce (fn [r i] (addm {:x r :y i})) 0 (range 128))=> 8128(quick-bench (reduce (fn [r i] (add r i)) 0 (range 128)))Evaluation count : 270720 in 6 samples of 45120 calls.             Execution time mean : 2.212768 µs    Execution time std-deviation : 76.515990 ns   Execution time lower quantile : 2.130557 µs ( 2.5%)   Execution time upper quantile : 2.336060 µs (97.5%)                   Overhead used : 1.902301 nsFound 1 outliers in 6 samples (16.6667 %)	low-severe	 1 (16.6667 %) Variance from outliers : 13.8889 % Variance is moderately inflated by outliers=> nil(quick-bench (reduce (fn [r i] (add r i)) 0 (range 128)))Evaluation count : 265158 in 6 samples of 44193 calls.             Execution time mean : 2.323233 µs    Execution time std-deviation : 176.530052 ns   Execution time lower quantile : 2.223932 µs ( 2.5%)   Execution time upper quantile : 2.626066 µs (97.5%)                   Overhead used : 1.902301 nsFound 1 outliers in 6 samples (16.6667 %)	low-severe	 1 (16.6667 %) Variance from outliers : 15.4138 % Variance is moderately inflated by outliers=> nil(quick-bench (reduce (fn [r i] (addm {:x r :y i})) 0 (range 128)))Evaluation count : 56208 in 6 samples of 9368 calls.             Execution time mean : 11.928436 µs    Execution time std-deviation : 950.653954 ns   Execution time lower quantile : 10.705623 µs ( 2.5%)   Execution time upper quantile : 13.069694 µs (97.5%)                   Overhead used : 1.902301 ns

(defn add [x y] (+ x y))
=> #'user/add

(defn addm [{x :x y :y}] (+ x y))
=> #'user/addm

(quick-bench (reduce (fn [r i] (add r i)) 0 (range 128)))
Evaluation count : 270720 in 6 samples of 45120 calls.
             Execution time mean : 2.212768 µs
    Execution time std-deviation : 76.515990 ns
   Execution time lower quantile : 2.130557 µs ( 2.5%)
   Execution time upper quantile : 2.336060 µs (97.5%)
                   Overhead used : 1.902301 ns

Found 1 outliers in 6 samples (16.6667 %)
	low-severe	 1 (16.6667 %)
 Variance from outliers : 13.8889 % Variance is moderately inflated by outliers
=> nil

(quick-bench (reduce (fn [r i] (add r i)) 0 (range 128)))
Evaluation count : 265158 in 6 samples of 44193 calls.
             Execution time mean : 2.323233 µs
    Execution time std-deviation : 176.530052 ns
   Execution time lower quantile : 2.223932 µs ( 2.5%)
   Execution time upper quantile : 2.626066 µs (97.5%)
                   Overhead used : 1.902301 ns

Found 1 outliers in 6 samples (16.6667 %)
	low-severe	 1 (16.6667 %)
 Variance from outliers : 15.4138 % Variance is moderately inflated by outliers
=> nil

(quick-bench (reduce (fn [r i] (addm {:x r :y i})) 0 (range 128)))
Evaluation count : 56208 in 6 samples of 9368 calls.
             Execution time mean : 11.928436 µs
    Execution time std-deviation : 950.653954 ns
   Execution time lower quantile : 10.705623 µs ( 2.5%)
   Execution time upper quantile : 13.069694 µs (97.5%)
                   Overhead used : 1.902301 ns

arity is several times faster than map args in Clojure.

Use arity on the inside for speed where the args are stable, use map args on the outside where you need the flexibility to change