Creating code on the fly using Clojure eval

Code

;; defining_functions_on_the_fly.clj

(eval `(def x 1))

x

(def map-vals
  {:a 10
   :b 20
   :c 30})

(doseq [[k v] map-vals]
  (eval
   `(defn ~(symbol k) []
      ~v)))

(a)
(b)
(c)



(def planets ["Earth" "Mars" "Venus" "Jupiter" "Saturn"])

;; Generate and define functions for each planet
(doseq [planet planets]
  (eval
   `(defn ~(symbol (str "hello-" (clojure.string/lower-case planet))) []
      ~(str "Hello " planet))))

;; Now you can call the generated functions:
(hello-earth)   ; => "Hello Earth"
(hello-mars)    ; => "Hello Mars"
(hello-venus)   ; => "Hello Venus"

Notes

• Eval in different namespaces