http://neuralnetworksanddeeplearning.com/chap1.html

adder.clj

(defn perceptron [inputs weights bias]
  {:pre [(= (count inputs) (count weights))]}
  (let [combined (map * inputs weights)]
    (if (< (+ (apply + combined) bias) 1) 0 1)))

(defn nand [one two]
  (perceptron [one two] [-2 -2] 3))

(defn adder [x y]
  "Returns a vector of [carry-bit sum-bit]"
  (let [f (nand x y)
        s (nand f f)]
    [s (nand (nand x f) (nand s f))]))