chickadee » sicp » ambeval-n

Amb-evaluates the expression, invoking the success-continuation n times or until failure.

exp

The expression to evaluate

env

The environment to evaluate it in

n

The maximum number of times to invoke the success continuation

(define (ambeval-n exp env n)
  (ambeval
    exp
    env
    (lambda (val next-alternative)
      (set! n (- n 1))
      (if (zero? n) val (next-alternative)))
    (lambda () failure)))