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maplist and lists
- To: David C. Plummer <DCP@QUABBIN.SCRC.Symbolics.COM>
- Subject: maplist and lists
- From: Brad Miller <miller@ACORN.CS.ROCHESTER.EDU>
- Date: Tue, 6 Jan 87 12:57 EST
- Cc: common-lisp@sail.stanford.edu, miller@ACORN.CS.ROCHESTER.EDU
- In-reply-to: <870106113546.5.DCP@KOYAANISQATSI.S4CC.Symbolics.COM>
- Organization: University of Rochester, Department of Computer Science
- Phone: 716-275-7747
- Postal-address: 617 Hylan Building, University of Rochester, Rochester NY 14627
- Reply-to: miller@cs.rochester.edu
- Sender: miller@cs.rochester.edu
Date: Tue, 6 Jan 87 11:35 EST
From: David C. Plummer <DCP@QUABBIN.SCRC.Symbolics.COM>
Date: Tue, 6 Jan 87 11:07 EST
From: Brad Miller <miller@ACORN.CS.ROCHESTER.EDU>
What do you want
(maplist #'list '(1 2 3 . 4) '(a b . c) '(x y z w q r s))
to return, and why? What I'm asking for is your "well defined"
definition.
(((1 2 3 . 4) (a b . c) (x y z w q r s))
((2 3 . 4) (b . c) (y z w q r s))
((3 . 4) c (z w q r s)))
since there are no further cdr's of the middle form that would be it!
One can argue that
w/o dotted lists one can continue to take cdrs (getting nil) until all lists
are ended, but using a dotted list, you "wave" that - one of the lists
finished, so there are no further maps to be done. Note that this is not a
problem it might be with MAPCAR, where a lot of information might be
(silently) lost, though the same principle could apply...
Brad Miller
------
miller@cs.rochester.edu
miller@acorn.cs.rochester.edu
miller@rochester.arpa