;; tests

(eval '(lazy-let (x 2) 2))

(eval '(lazy-let (x 2) x))

(eval '(lazy-let (x (/ 5 0)) 7))

(eval '(lazy-let (y 2)
                 (lazy-let (x y)
                            x)))

(eval '(lazy-let (x (lazy-let (y 2) y))
                 (+ x 1)))

(eval '(lazy-let (x (lambda (a) (+ a 1)))
                 (x 2)))

(eval '(lazy-let (x (lambda (x) (+ x 1)))
                 (x 2)))


(eval '(lazy-let (x ((lambda-rec (append xs ys)
                                 (if (null? xs)
                                     ys
                                     (cons (car xs)
                                           (append (cdr xs) ys))))
                     (cons 2 (cons 3 null))
                     (cons 4 (cons 5 null))))
                 x))


(eval '(lazy-let (x (lambda-rec (append xs ys)
                                (if (null? xs)
                                    ys
                                    (cons (car xs)
                                          (append (cdr xs) ys)))))
                 (x (cons 2 (cons 3 null))
                    (cons 4 (cons 5 null)))))

(eval '((lambda-rec (fact n)
                    (lazy-let (t 1)
                              (lazy-let (f (* n (fact (- n 1))))
                                        (if (= n 0)
                                            t
                                            f))))
        12))

(eval '(let [x 4]
            (lazy-let [y (+ x 1)]
                      (let [x 10]
                            y))))