(define null? not)

(define err? (lambda (x) (eq? x 'ERR)))

(define number? (lambda (x) (eq? (* 0 x) 0)))

(define pair? (lambda (x) (not (err? (cdr x)))))

(define symbol?
    (lambda (x)
      (and
       x
       (not (err? x))
       (not (number? x))
       (not (pair? x)))))

(define atom?
    (lambda (x)
      (or
       (not x)
       (symbol? x))))

(define list?
    (lambda (x)
      (if (not x)
          #t
          (if (pair? x)
              (list? (cdr x))
              ()))))

(define equal?
    (lambda (x y)
      (or
       (eq? x y)
       (and
        (pair? x)
        (pair? y)
        (equal? (car x) (car y))
        (equal? (cdr x) (cdr y))))))

(define negate (lambda (n) (- 0 n)))

(define > (lambda (x y) (< y x)))

(define <= (lambda (x y) (not (< y x))))

(define >= (lambda (x y) (not (< x y))))

(define = (lambda (x y) (eq? (- x y) 0)))

(define list (lambda args args))

(define cadr (lambda (x) (car (cdr x))))

(define caddr (lambda (x) (car (cdr (cdr x)))))

(define begin (lambda (x . args) (if args (begin . args) x)))

(define length
    (lambda (t)
      (if t
          (+ 1 (length (cdr t)))
          0)))

(define append1
    (lambda (s t)
      (if s
          (cons (car s) (append1 (cdr s) t))
          t)))

(define append
    (lambda (t . args)
      (if args
          (append1 t (append . args))
          t)))

(define nthcdr
    (lambda (t n)
      (if (eq? n 0)
          t
          (nthcdr (cdr t) (- n 1)))))

(define nth (lambda (t n) (car (nthcdr t n))))

(define rev1
    (lambda (r t)
      (if t
          (rev1 (cons (car t) r) (cdr t))
          r)))

(define reverse (lambda (t) (rev1 () t)))

(define member
    (lambda (x t)
      (if t
          (if (equal? x (car t))
              t
              (member x (cdr t)))
          t)))

(define foldr
    (lambda (f x t)
      (if t
          (f (car t) (foldr f x (cdr t)))
          x)))

(define foldl
    (lambda (f x t)
      (if t
          (foldl f (f (car t) x) (cdr t))
          x)))

(define min
    (lambda args
      (foldl
       (lambda (x y)
         (if (< x y)
             x
             y))
       9.999999999e99
       args)))

(define max
    (lambda args
      (foldl (lambda (x y)
               (if (< x y)
                   y
                   x))
             -9.999999999e99
             args)))

(define filter
    (lambda (f t)
      (if t
          (if (f (car t))
              (cons (car t) (filter f (cdr t)))
              (filter f (cdr t)))
          ())))

(define all?
    (lambda (f t)
      (if t
          (and
           (f (car t))
           (all? f (cdr t)))
          #t)))

(define any?
    (lambda (f t)
      (if t
          (or
           (f (car t))
           (any? f (cdr t)))
          ())))

(define mapcar
    (lambda (f t)
      (if t
          (cons (f (car t)) (mapcar f (cdr t)))
          ())))

(define map
    (lambda (f . args)
      (if (any? null? args)
          ()
          (let*
              (x (mapcar car args))
            (t (mapcar cdr args))
            (cons (f . x) (map f . t))))))

(define zip (lambda args (map list . args)))

(define seq
    (lambda (n m)
      (if (< n m)
          (cons n (seq (+ n 1) m))
          ())))

(define seqby
    (lambda (n m k)
      (if (< 0 (* k (- m n)))
          (cons n (seqby (+ n k) m k))
          ())))

(define range
    (lambda (n m . args)
      (if args
          (seqby n m (car args))
          (seq n m))))
(define abs
    (lambda (n)
      (if (< n 0)
          (- 0 n)
          n)))

(define frac (lambda (n) (- n (int n))))

(define truncate int)

(define floor
    (lambda (n)
      (int
       (if (< n 0)
           (- n 1)
           n))))

(define ceiling (lambda (n) (- 0 (floor (- 0 n)))))

(define round (lambda (n) (+ (floor n) 0.5)))

(define mod (lambda (n m) (- n (* m (int (/ n m))))))

(define gcd
    (lambda (n m)
      (if (eq? m 0)
          n
          (gcd m (mod n m)))))

(define lcm (lambda (n m) (/ (* n m) (gcd n m))))

(define even? (lambda (n) (eq? (mod n 2) 0)))

(define odd? (lambda (n) (eq? (mod n 2) 1)))

(define curry (lambda (f x) (lambda args (f x . args))))

(define compose (lambda (f g) (lambda args (f (g . args)))))

(define Y (lambda (f) (lambda args ((f (Y f)) . args))))

(define reveal (lambda (f) (cons 'lambda (cons (car (car f)) (cons (cdr (car f)) ())))))

(define defun (macro (f v x) (list 'define f (list 'lambda v x))))