Hi gurus,

I found a very interesting artical about AMB.This is a very interesting and useful function. We can use it to solve many questions. For example:
"Baker, Cooper, Fletcher, Miller, and Smith live on different floors of an apartment house that contains only five floors. Baker does not live on the top floor. Cooper does not live on the bottom floor. Fletcher does not live on either the top or the bottom floor. Miller lives on a higher floor than does Cooper. Smith does not live on a floor adjacent to Fletcher's. Fletcher does not live on a floor adjacent to Cooper's. Where does everyone live?"
scheme code is as followings: 
(define (require p)
(if (not p) (amb)))

(define (distinct? items)
    (cond ((null? items) true)
          ((null? (cdr items)) true)
          ((member (car items) (cdr items)) false)
          (else (distinct? (cdr items)))))

(define (multiple-dwelling)
  (let  ((baker  (amb 1 2 3 4 5))
         (cooper (amb 1 2 3 4 5))
         (fletcher  (amb 1 2 3 4 5))
         (miller (amb 1 2 3 4 5))
         (smith  (amb 1 2 3 4 5))
      (require
       (distinct? (list baker cooper fletcher miller smith)))
(require (not (= baker 5)))
(require (not (= cooper 1)))
(require (not (= fletcher 5)))
(require (not (= fletcher 1)))
(require (> miller cooper)))
(require (not (= (abs (- smith fletch)) 1)))
(require (not (= (abs (- fletcher cooper)) 1)))
(list (list 'baker baker)
      (list 'cooper cooper)
      (list 'fletcher fletcher)
      (list 'miller miller)
      (list 'smith smith))))

[download]
I have attempt to implement amb function in perl, but failed. Compared to scheme, It seems that perl couldn't deal with continuation.

Any suggestions?

I am trying to improve my English skills, if you see a mistake please feel free to reply or /msg me a correction

In reply to How implement AMB in perl? by xiaoyafeng

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