# [plt-scheme] why local? (just curious)

Sorry but... why for n < 6?
Shriram Krishnamurthi schrieb:
>>* Now I've tried to think up an example myself in which both is present -
*>>* as I can't get at anything sensible, I just put some sequential
*>>* assignment in the beginning of the classic even-odd-letrec-example:
*>>*
*>>* (define test
*>>* (lambda (n)
*>>* (letrec ((start-value n)
*>>* (zero (- start-value start-value))
*>>* (even? (lambda (n) (if (= n zero) #t (odd? (- n 1)))))
*>>* (odd? (lambda (n) (if (= n zero) #f (even? (- n 1))))))
*>>* (odd? n))))
*>>*
*>>* (test 333)
*>>*
*>*
*>* The meaning of this program is undefined according to RnRS for n < 6.
*>* Which means: In some implementations, it produces the answer you
*>* expect. In other implementations, it yields an error. In still other
*>* implementations, it might produce a different answer (or undefined, or
*>* error) depending on the phase of the moon.
*>*
*>* Shriram
*>*
*>*
*