impls/lib/trivial.mal

   1 ;; Trivial but convenient functions.
   2
   3 ;; Integer predecessor (number -> number)
   4 (def! inc (fn* [a] (+ a 1)))
   5
   6 ;; Integer predecessor (number -> number)
   7 (def! dec (fn* (a) (- a 1)))
   8
   9 ;; Integer nullity test (number -> boolean)
  10 (def! zero? (fn* (n) (= 0 n)))
  11
  12 ;; Returns the unchanged argument.
  13 (def! identity (fn* (x) x))
  14
  15 ;; Generate a hopefully unique symbol. See section "Plugging the Leaks"
  16 ;; of http://www.gigamonkeys.com/book/macros-defining-your-own.html
  17 (def! gensym
  18   (let* [counter (atom 0)]
  19     (fn* []
  20       (symbol (str "G__" (swap! counter inc))))))