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fill-pointers and destructive sequence functions
- To: common-lisp@SU-AI.ARPA
- Subject: fill-pointers and destructive sequence functions
- From: Rob MacLachlan <RAM@C.CS.CMU.EDU>
- Date: Sun, 12 Jan 1986 13:42:00 -0000
If a destructive sequence function such as DELETE is passed an
array with a fill pointer, may it reduce the size of the argument by
adjusting the fill-pointer? The alternative would be to require the
(ARRAY-DIMENSION <res> 0) to be the resulting length. This seems
excessively restrictive, since sequence functions only deal with the
active elements of vectors.
What should ADJUST-ARRAY do with the fill-pointer in an array if
there is no :FILL-POINTER argument specified? It seems sub-optimal to
leave it pointing into hyperspace. Does the fill pointer go away?
Is it legal for MAKE-ARRAY to return an array with a fill-pointer
when no :FILL-POINTER option was specified? This question is similar
to the question "Are there contexts in which not having a fill-pointer
is important?" Currently any Spice Lisp vector which is not a
SIMPLE-ARRAY has a fill pointer.