[plt-scheme] Why no zip in "list.ss"?

Good grief! I don't know how you keep coming up with things that leave me thinking "Why didn't I think of that?"

Anyway, I noticed that the SRFI was in help desk, but didn't know how or if they were available for use. 

Thanks.
--------------------------
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----- Original Message -----
From: Danny Yoo <dyoo at hkn.eecs.berkeley.edu>
To: Woodhouse, Gregory J.
Cc: plt-scheme at list.cs.brown.edu <plt-scheme at list.cs.brown.edu>
Sent: Wed Dec 27 12:59:35 2006
Subject: Re: [plt-scheme] Why no zip in "list.ss"?

> I could have sworn that zip was included in list.ss, but apparently not. 
> Certainly, it seems a natural.

Hi Gregory,

Here's an alternative implementation that you might like:

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
> (define (zip l1 l2)
     (map list l1 l2))
>
> (zip '(1 2 3 4 5) '(one two three four five))
((1 one) (2 two) (3 three) (4 four) (5 five))
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;


But the ZIP function you're thinking of does exist in the SRFI-1 "list" 
library.  We can also say:

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
> (require (only (lib "1.ss" "srfi") zip))
>
> (zip '(1 2 3 4 5)
        '(one two three four five))
((1 one) (2 two) (3 three) (4 four) (5 five))
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;


See:

  http://download.plt-scheme.org/doc/360/html/srfi/srfi-1.html
  http://download.plt-scheme.org/doc/360/html/r5rs/r5rs-Z-H-9.html#%25_idx_580

for more details.  Good luck!