[racket] HtDP, andmap & ormap
Sorry, Matthias, that was dumb of me to post my solution. What should
I have done? Should I have just asserted there was no real use of
ormap & andmap in HtDP? Should I have said that that exercise didn't
IMO require andmap? Should I not have discussed the exercise at all?
Is this even a good list to ask questions about good program design?
David, I didn't understand what your code was supposed to show.
That's good you know how to replicate draw.ss in universe. I thought
about doing it, as the docs point you that way, but didn't see how.
Why do you think that HtDP's ormap is different from Racket's ormap?
HtDP Figure 57:
;; ormap : (X -> boolean) (listof X) -> boolean
;; to determine whether p holds for at least one item on alox
;; that is, (ormap p (list x-1 ... x-n)) = (or (p x-1) (or ... (p x-n)))
That's the ormap described when you hit:
ormap provided from racket/base, racket
Now that's a bit different from what's described when you hit:
ormap provided from lang/htdp-advanced
(ormap p (list x-1 ... x-n)) = (or (p x-1) ... (p x-n))
I assume that's a documentation bug, as Advanced Student has set!, so
it matters if you evaluate all the later (p x-i)s after you get a
non-#f value. I should try it out to be sure.