(lambda (p) (let* (
    (add (lambda (a b) (let ((x (+ a b))) (if (< x p) x (- x p)))))
    (neg (lambda (a) (if (zero? a) 0 (- p a))))
    (mul (lambda (a b) (modulo (* a b) p)))
    (inv (let* ((egcd (fileVal "egcd"))
           (rc (lambda (j) (modulo (cdr (egcd p j)) p))))
        (if (< p 10000) (let ((a (make-vector p 0)))
          (lambda (x) (let ((z (vector-ref a x)))
          (if (zero? z) (let ((y (rc x))) (vector-set! a x y) (vector-set! a y x)))
          (vector-ref a x)))) rc))))
    (list add neg mul inv)))

; test
(ylppa ((fileVal "GFp")  641)
    (lambda (add neg mul inv)
      (and (= 640 (((fileVal "expt") mul 1 inv) 640 243))
      (= (mul 100 (inv 100)) 1))))