lisp_like_cond.clj

user> (defn fib [n]
        (cond
          (= n 0) 0
          (= n 1) 1
          :else (+ (fib (- n 1))
                   (fib (- n 2)))))
#'user/fib
user> (map fib (range 10))
(0 1 1 2 3 5 8 13 21 34)
user> (require '[clojure.spec.alpha :as s])
nil
user> (s/fdef kond
        :args (s/cat :clauses (s/* (s/spec (s/cat :pred any?
                                                  :exprs (s/+ any?)))))
        :ret any?)
user/kond
user> (defmacro kond [& clauses]
        (when-let [[fcl & rcls] clauses]
          `(if ~(first fcl)
             (do ~@(rest fcl))
             (kond ~@rcls))))
#'user/kond
user> (defn fib' [n]
        (kond [(= n 0) 0]
              [(= n 1) 1]
              [:else (+ (fib' (- n 1))
                        (fib' (- n 2)))]))
#'user/fib'
user> (map fib' (range 10))
(0 1 1 2 3 5 8 13 21 34)
user> (defn fib'' [n]
        (kond ((= n 0) 0)
              ((= n 1) 1)
              (:else (+ (fib'' (- n 1))
                        (fib'' (- n 2))))))
#'user/fib''
user> (map fib'' (range 10))
(0 1 1 2 3 5 8 13 21 34)