(defmacro defun
    (name args body)
    `(def ~name (fn ~args ~body)))

; Unique symbols generation
(def *__gensym-counter__* (atom 0))
(defun gensym
    ()
    (symbol (str "G__"
        (swap *__gensym-counter__*
            (fn (x) (+ 1 x))))))

(defun inc (a) (+ 1 a))
(defun dec (a) (- a 1))

(defmacro or
    (& xs)
    (if (empty? xs)
        ()
        (if (= 1 (count xs))
            (first xs)
            (let (condvar (gensym))
                `(let (~condvar ~(first xs))
                    (if ~condvar ~condvar (or ~@(rest xs))))))))

(defmacro and
    (& xs)
    (if (empty? xs)
        ()
        (if (= 1 (count xs))
            (first xs)
            (let (condvar (gensym))
                `(let (~condvar ~(first xs))
                    (if ~condvar (and ~@(rest xs)) ~condvar))))))

(defmacro cond
    (& xs)
    (if (> (count xs) 0)
        (list 'if (first xs)
            (if (> (count xs) 1)
                (nth xs 1)
                (throw "odd number of forms to cond"))
            (cons 'cond (rest (rest xs))))
        ()))

true