> On Mar 11, 2020, at 12:52 AM, Joo ChurlSoo <xxxxxx@gmail.com> wrote:
>
>
> | For example:
> | (define x 1)
> | (define y 2)
> | (define a (adbmal x y))
> | (define a* (adbmal* x y))
> | (define v (values x y))		error:racket
> | (define v* (lambda () (values x y)))
> | (define listxy (lambda (x y) (list x y)))
>
> | (a listxy)        	       	= (1 2)
> | (a* listxy)      	      	= (1 2)
> | (call-with-values v listxy)  	error
> | (call-with-values v* listxy)    = (1 2)
> | (receive (x y) v (list x y))	error or (1 2):gambit
> | (receive (x y) v* (list x y))	error
> | (receive (x y) (v*) (list x y)) = (1 2)
>
> | (set! x 10)
> | (set! y 20)
> | (a listxy)	       	       	= (10 20)
> | (a* listxy)      	      	= (1 2)
> | (call-with-values v* listxy)    = (10 20)
> | (receive (x y) (v*) (list x y)) = (10 20)
> | (receive (x y) v (list x y))	error or (1 2):gambit
>
> By the way, which do you think is correct, racket or gambit?

Actually both… a Scheme implementation is free to do what it wants when the standard says “it is an error”.  Here Gambit allows values that are “multiple values” to be stored in variables.  This is convenient in various situations that need to handle multiple values as an aggregate.

Marc