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This SRFI proposes a comprehensive and complete library of vector operations accompanied by a freely available and complete reference implementation. The reference implementation is unencumbered by copyright, and useable with no modifications on any Scheme system that is R5RS-compliant. It also provides several hooks for implementation-specific optimization as well.
Because this SRFI is more of a library or module specification than a request for additions to readers or any other internal implementation detail, in an implementation that supports a module or structure or package or library or unit (et cetera) systems, these procedures should be contained in a module / structure / package / library / unit called vector-lib.
R5RS provides very few list-processing procedures, for which reason SRFI 1 (list-lib) exists. However, R5RS provides even fewer vector operations — while it provides mapping, appending, et cetera operations for lists, it specifies only nine vector manipulation operations —:
Many Scheme implementations provide several vector operations beyond the miniscule set that R5RS defines (the typical vector-append, vector-map, et cetera), but often these procedures have different names, take arguments in different orders, don't take the same number of arguments, or have some other flaw that makes them unportable. For this reason, this SRFI is proposed.
It should be noted that no vector sorting procedures are provided by this SRFI, because there already is a SRFI for such a purpose (SRFI 32 (sort-lib)), which includes routines for sorting not only vectors but also lists.
Here is an index of the procedures provided by this package. Those marked by bold are provided in R5RS and those marked by bold italic are defined by R5RS but are modified from their original definitions.
make-vector
vector
vector-unfold
vector-unfold-right
vector-copy
vector-reverse-copy
vector-append
vector-concatenate
vector?
vector-empty?
vector=
vector-ref
vector-length
vector-fold
vector-fold-right
vector-map
vector-map!
vector-for-each
vector-count
vector-index
vector-index-right
vector-skip
vector-skip-right
vector-binary-search
vector-any
vector-every
vector-set!
vector-swap!
vector-fill!
vector-reverse!
vector-copy!
vector-reverse-copy!
vector->list
reverse-vector->list
list->vector
reverse-list->vector
In this section containing specifications of procedures, the following notation is used to specify parameters and return values:
[start [end]]
It should be noted that all of the procedures that iterate across multiple vectors in parallel stop iterating and produce the final result when the end of the shortest vector is reached. The sole exception is vector=, which automatically returns #f if the vectors' lengths vary.
(make-vector 5 3)
#(3 3 3 3 3)
(vector 0 1 2 3 4)
#(0 1 2 3 4)
(vector-copy '#(a b c d e f g h i))
#(a b c d e f g h i)
(vector-copy '#(a b c d e f g h i) 6)
#(g h i)
(vector-copy '#(a b c d e f g h i) 3 6)
#(d e f)
(vector-copy '#(a b c d e f g h i) 6 12 'x)
#(g h i x x x)
(vector-reverse-copy '#(5 4 3 2 1 0) 1 5)
#(1 2 3 4)
(vector-append '#(x) '#(y))
#(x y)
(vector-append '#(a) '#(b c d))
#(a b c d)
(vector-append '#(a #(b)) '#(#(c)))
#(a #(b) #(c))
(apply vector-append
list-of-vectors)
(vector-concatenate '(#(a b) #(c d)))
#(a b c d)
(vector? '#(a b c))
#t
(vector? '(a b c))
#f
(vector? #t)
#f
(vector? '#())
#t
(vector? '())
#f
(vector-empty? '#(a))
#f
(vector-empty? '#(()))
#f
(vector-empty? '#(#()))
#f
(vector-empty? '#())
#t
(vector= eq? '#(a b c d) '#(a b c d))
#t
(vector= eq? '#(a b c d) '#(a b d c))
#f
(vector= = '#(1 2 3 4 5) '#(1 2 3 4))
#f
(vector= = '#(1 2 3 4) '#(1 2 3 4))
#t
(vector= eq?)
#t
(vector= eq? '#(a))
#t
(vector= eq? (vector (vector 'a)) (vector (vector 'a)))
#f
(vector= equal? (vector (vector 'a)) (vector (vector 'a)))
#t
(vector-ref '#(a b c d) 2)
c
(vector-length '#(a b c))
3
(vector-fold (λ (index len str)
(max (string-length str) len))
0 vector-of-strings)
(vector-fold (λ (index tail elt) (cons elt tail))
'() vec)
(vector-fold (λ (index n counter)
(if (even? n) (+ counter 1) counter))
0 vec)
(vector-fold-right (λ (index elt tail)
(cons elt tail))
'() '#(a b c d))
(a b c d)
(vector-map (λ (i x) (* x x))
(vector-unfold
(λ (i x) (values x (+ x 1)))
4 1))
#(1 4 9 16)
(vector-map (λ (i x y) (* x y))
(vector-unfold
(λ (i x) (values x (+ x 1)))
5 1)
(vector-unfold
(λ (i x) (values x (- x 1)))
5 5))
#(5 8 9 8 5)
(let ((count 0))
(vector-map (λ (ignored-index ignored-elt)
(set! count (+ count 1))
count)))
'#(a b)
#(1 2) OR #(2 1)
(vector-map (λ (i elt) (+ i elt)) '#(1 2 3 4))
#(1 3 5 7)
(vector-for-each (λ (i x) (display x) (newline))
'#("foo" "bar" "baz" "quux" "zot"))
foo bar baz quux zot
(vector-count (λ (i elt) (even? elt))
'#(3 1 4 1 5 9 2 5 6))
3
(vector-count (λ (i x y) (< x y))
'#(1 3 6 9) '#(2 4 6 8 10 12))
2
(vector-index even? '#(3 1 4 1 5 9))
2
(vector-index < '#(3 1 4 1 5 9 2 5 6) '#(2 7 1 8 2))
1
(vector-index = '#(3 1 4 1 5 9 2 5 6) '#(2 7 1 8 2))
#f
(vector-index
(λ (x_{1} x_{2}
···)
(not (pred? x_{1}
x_{1}
···)))
vec_{1} vec_{2}
···)
(vector-skip number? '#(1 2 a b 3 4 c d))
2
(vector-index-right
(λ (x_{1} x_{2}
···)
(not (pred? x_{1}
x_{1}
···)))
vec_{1} vec_{2}
···)
(λ (char_{1} char_{2})
(cond ((char<? char_{1}
char_{2})
-1)
((char=? char_{1}
char_{2})
0)
(else 1)))
With this SRFI comes a complete reference implementation. It is
licensed under a very open copyright with which no implementors
should have any legal issues.
The reference implementation has only one non-R5RS dependency:
SRFI 23's error procedure.
This reference implementation of all the procedures described in
this SRFI can be found here.
Thanks to Olin Shivers for his wonderfully complete list and string packages; to all the members of the #scheme IRC channel on Freenode who nitpicked a great deal, but also helped quite a lot in general, and helped test the reference implementation in various Scheme systems; to Michael Burschik for his numerous comments; to Sergei Egorov for helping to narrow down the procedures; to Mike Sperber for putting up with an extremely overdue draft; to Felix Winkelmann for continually bugging me about finishing up the SRFI so that it would be only overdue and not withdrawn; and to everyone else who gave questions, comments, thoughts, or merely attention to the SRFI.
Copyright (C) Taylor Campbell (2003). All rights reserved.
This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published, and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Scheme Request For Implementation process or editors, except as needed for the purpose of developing SRFIs in which case the procedures for copyrights defined in the SRFI process must be followed, or as required to translate it into languages other than English.
The limited permissions granted above are perpetual and will not be revoked by the authors or their successors or assigns.
This document and the information contained herein are provided on an "AS IS" basis and THE AUTHOR AND THE SRFI EDITORS DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNISS FOR A PARTICULAR PURPOSE.