方案递归函数与多个lambda

Question

如何从使过程递归的函数中生成过程?

例如，让我们有一个返回过程的函数，返回的过程将接受两个参数(x和y)。当以z作为参数调用时，它将递归地调用自己，直到z满足某些要求

(define test
  (lambda (x y)
    (lambda z
      (if (> z 100)
          z
          (RecursiveCallToChangeValueOfZ (+ x y z))))))

Answer 1

这里有三个变体:

#lang racket
;; use internal definition
(define test
  (lambda (x y)
    (define f
      (lambda z
        (if (> z 100)
            z
            (f (+ x y z)))))
    f))
;; use letrec (which internal definition expands to    
(define test2
  (lambda (x y)
    (letrec ([f (lambda z
                  (if (> z 100)
                      z
                      (f (+ x y z))))])
      f)))
(require mzlib/etc)
;; use rec (a little syntactic sugar that expands to the previous solution)
(define test3
  (lambda (x y)
    (rec f (lambda z
             (if (> z 100)
                 z
                 (f (+ x y z)))))))