[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: perhaps I've missed something ...

This page is part of the web mail archives of SRFI 17 from before July 7th, 2015. The new archives for SRFI 17 contain all messages, not just those from before July 7th, 2015.

sperber@xxxxxxxxxxxxxxxxxxxxxxxxxxx (Michael Sperber [Mr. Preprocessor]) writes:

> me> 1. what I, in my naivete about PL design, take "set!" to be?
> me> (set! <name> <value>) translates, in my mind, to: dear Scheme, please
> me> make it so that next time I say <name>, and <name> denotes the same
> me> thing as now, I get <value>.
> But this intuition is wrong

I think you missed the now-underlined part.

> , because SET! has interaction with *place*
> (in the program source code) in addition to interaction with time.
> (define x 23)
> (let ((x 5))
>   (set! x 17))
> x => 23
> This is precisely the case students struggle with.

I really begin to wonder about your students...

> Cheers =8-} Mike


Tools that are no good require more skill.