* Array or Vector?
@ 2008-09-10 15:11 Nordlöw
2008-09-10 15:57 ` Drew Adams
0 siblings, 1 reply; 2+ messages in thread
From: Nordlöw @ 2008-09-10 15:11 UTC (permalink / raw
To: help-gnu-emacs
When, in Emacs Lisp, is it preferrable to use a list over a vector and
vice versa?
My guess is
- vector: for fast static sequences
- list: for dynamically growing sequences
/Nordlöw
^ permalink raw reply [flat|nested] 2+ messages in thread
* RE: Array or Vector?
2008-09-10 15:11 Array or Vector? Nordlöw
@ 2008-09-10 15:57 ` Drew Adams
0 siblings, 0 replies; 2+ messages in thread
From: Drew Adams @ 2008-09-10 15:57 UTC (permalink / raw
To: 'Nordlöw', help-gnu-emacs
> When, in Emacs Lisp, is it preferrable to use a list over a vector and
> vice versa?
>
> My guess is
> - vector: for fast static sequences
> - list: for dynamically growing sequences
Yes (growing, shrinking, ...). And array, not necessarily vector.
See Elisp manual, node Sequences Arrays Vectors:
An "array" is a single primitive object that has a slot for each of
its elements. All the elements are accessible in constant time, but
the length of an existing array cannot be changed. Strings, vectors,
char-tables and bool-vectors are the four types of arrays.
A list is a sequence of elements, but it is not a single primitive
object; it is made of cons cells, one cell per element. Finding the
Nth element requires looking through N cons cells, so elements farther
from the beginning of the list take longer to access. But it is
possible to add elements to the list, or remove elements.
The Elisp manual is your friend.
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