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1 | ;;;; common-list.scm --- COMMON LISP list functions for Scheme |
2 | ;;;; | |
c771038b TTN |
3 | ;;;; Copyright (C) 1995, 1996, 1997, 2001 Free Software Foundation, Inc. |
4 | ;;;; | |
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5 | ;;;; This program is free software; you can redistribute it and/or modify |
6 | ;;;; it under the terms of the GNU General Public License as published by | |
7 | ;;;; the Free Software Foundation; either version 2, or (at your option) | |
8 | ;;;; any later version. | |
c771038b | 9 | ;;;; |
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10 | ;;;; This program is distributed in the hope that it will be useful, |
11 | ;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 | ;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
13 | ;;;; GNU General Public License for more details. | |
c771038b | 14 | ;;;; |
6a4d3cfd JB |
15 | ;;;; You should have received a copy of the GNU General Public License |
16 | ;;;; along with this software; see the file COPYING. If not, write to | |
17 | ;;;; the Free Software Foundation, Inc., 59 Temple Place, Suite 330, | |
18 | ;;;; Boston, MA 02111-1307 USA | |
a482f2cc MV |
19 | ;;;; |
20 | ;;;; As a special exception, the Free Software Foundation gives permission | |
21 | ;;;; for additional uses of the text contained in its release of GUILE. | |
22 | ;;;; | |
23 | ;;;; The exception is that, if you link the GUILE library with other files | |
24 | ;;;; to produce an executable, this does not by itself cause the | |
25 | ;;;; resulting executable to be covered by the GNU General Public License. | |
26 | ;;;; Your use of that executable is in no way restricted on account of | |
27 | ;;;; linking the GUILE library code into it. | |
28 | ;;;; | |
29 | ;;;; This exception does not however invalidate any other reasons why | |
30 | ;;;; the executable file might be covered by the GNU General Public License. | |
31 | ;;;; | |
32 | ;;;; This exception applies only to the code released by the | |
33 | ;;;; Free Software Foundation under the name GUILE. If you copy | |
34 | ;;;; code from other Free Software Foundation releases into a copy of | |
35 | ;;;; GUILE, as the General Public License permits, the exception does | |
36 | ;;;; not apply to the code that you add in this way. To avoid misleading | |
37 | ;;;; anyone as to the status of such modified files, you must delete | |
38 | ;;;; this exception notice from them. | |
39 | ;;;; | |
40 | ;;;; If you write modifications of your own for GUILE, it is your choice | |
41 | ;;;; whether to permit this exception to apply to your modifications. | |
42 | ;;;; If you do not wish that, delete this exception notice. | |
c771038b TTN |
43 | ;;;; |
44 | ||
45 | ;;; Commentary: | |
46 | ||
47 | ;; These procedures are exported: | |
48 | ;; (adjoin e l) | |
49 | ;; (union l1 l2) | |
50 | ;; (intersection l1 l2) | |
51 | ;; (set-difference l1 l2) | |
52 | ;; (reduce-init p init l) | |
53 | ;; (reduce p l) | |
54 | ;; (some pred l . rest) | |
55 | ;; (every pred l . rest) | |
56 | ;; (notany pred . ls) | |
57 | ;; (notevery pred . ls) | |
58 | ;; (count-if pred l) | |
59 | ;; (find-if pred l) | |
60 | ;; (member-if pred l) | |
61 | ;; (remove-if pred l) | |
62 | ;; (remove-if-not pred l) | |
63 | ;; (delete-if! pred l) | |
64 | ;; (delete-if-not! pred l) | |
65 | ;; (butlast lst n) | |
66 | ;; (and? . args) | |
67 | ;; (or? . args) | |
68 | ;; (has-duplicates? lst) | |
69 | ;; (pick p l) | |
70 | ;; (pick-mappings p l) | |
71 | ;; (uniq l) | |
72 | ;; | |
73 | ;; See docstrings for each procedure for more info. See also module | |
74 | ;; `(srfi srfi-1)' for a complete list handling library. | |
75 | ||
76 | ;;; Code: | |
6a4d3cfd | 77 | \f |
a6401ee0 JB |
78 | (define-module (ice-9 common-list)) |
79 | ||
80 | ;;"comlist.scm" Implementation of COMMON LISP list functions for Scheme | |
81 | ; Copyright (C) 1991, 1993, 1995 Aubrey Jaffer. | |
82 | ; | |
83 | ;Permission to copy this software, to redistribute it, and to use it | |
84 | ;for any purpose is granted, subject to the following restrictions and | |
85 | ;understandings. | |
86 | ; | |
87 | ;1. Any copy made of this software must include this copyright notice | |
88 | ;in full. | |
89 | ; | |
90 | ;2. I have made no warrantee or representation that the operation of | |
91 | ;this software will be error-free, and I am under no obligation to | |
92 | ;provide any services, by way of maintenance, update, or otherwise. | |
93 | ; | |
94 | ;3. In conjunction with products arising from the use of this | |
95 | ;material, there shall be no use of my name in any advertising, | |
96 | ;promotional, or sales literature without prior written consent in | |
97 | ;each case. | |
98 | ||
c771038b TTN |
99 | (define-public (adjoin e l) |
100 | "Return list L, possibly with element E added if it is not already in L." | |
16693054 | 101 | (if (memq e l) l (cons e l))) |
a6401ee0 JB |
102 | |
103 | (define-public (union l1 l2) | |
c771038b TTN |
104 | "Return a new list that is the union of L1 and L2. |
105 | Elements that occur in both lists occur only once in | |
106 | the result list." | |
a6401ee0 JB |
107 | (cond ((null? l1) l2) |
108 | ((null? l2) l1) | |
109 | (else (union (cdr l1) (adjoin (car l1) l2))))) | |
110 | ||
111 | (define-public (intersection l1 l2) | |
c771038b TTN |
112 | "Return a new list that is the intersection of L1 and L2. |
113 | Only elements that occur in both lists occur in the result list." | |
e5d2c2fa DH |
114 | (if (null? l2) l2 |
115 | (let loop ((l1 l1) (result '())) | |
116 | (cond ((null? l1) (reverse! result)) | |
117 | ((memv (car l1) l2) (loop (cdr l1) (cons (car l1) result))) | |
118 | (else (loop (cdr l1) result)))))) | |
a6401ee0 JB |
119 | |
120 | (define-public (set-difference l1 l2) | |
16693054 | 121 | "Return elements from list L1 that are not in list L2." |
e5d2c2fa DH |
122 | (let loop ((l1 l1) (result '())) |
123 | (cond ((null? l1) (reverse! result)) | |
124 | ((memv (car l1) l2) (loop (cdr l1) result)) | |
125 | (else (loop (cdr l1) (cons (car l1) result)))))) | |
a6401ee0 JB |
126 | |
127 | (define-public (reduce-init p init l) | |
16693054 | 128 | "Same as `reduce' except it implicitly inserts INIT at the start of L." |
a6401ee0 JB |
129 | (if (null? l) |
130 | init | |
131 | (reduce-init p (p init (car l)) (cdr l)))) | |
132 | ||
133 | (define-public (reduce p l) | |
c771038b TTN |
134 | "Combine all the elements of sequence L using a binary operation P. |
135 | The combination is left-associative. For example, using +, one can | |
136 | add up all the elements. `reduce' allows you to apply a function which | |
16693054 GB |
137 | accepts only two arguments to more than 2 objects. Functional |
138 | programmers usually refer to this as foldl." | |
a6401ee0 JB |
139 | (cond ((null? l) l) |
140 | ((null? (cdr l)) (car l)) | |
141 | (else (reduce-init p (car l) (cdr l))))) | |
142 | ||
143 | (define-public (some pred l . rest) | |
16693054 | 144 | "PRED is a boolean function of as many arguments as there are list |
c771038b TTN |
145 | arguments to `some', i.e., L plus any optional arguments. PRED is |
146 | applied to successive elements of the list arguments in order. As soon | |
147 | as one of these applications returns a true value, return that value. | |
148 | If no application returns a true value, return #f. | |
149 | All the lists should have the same length." | |
a6401ee0 JB |
150 | (cond ((null? rest) |
151 | (let mapf ((l l)) | |
152 | (and (not (null? l)) | |
153 | (or (pred (car l)) (mapf (cdr l)))))) | |
154 | (else (let mapf ((l l) (rest rest)) | |
155 | (and (not (null? l)) | |
156 | (or (apply pred (car l) (map car rest)) | |
157 | (mapf (cdr l) (map cdr rest)))))))) | |
158 | ||
159 | (define-public (every pred l . rest) | |
16693054 GB |
160 | "Return #t iff every application of PRED to L, etc., returns #t. |
161 | Analogous to `some' except it returns #t if every application of | |
162 | PRED is #t and #f otherwise." | |
a6401ee0 JB |
163 | (cond ((null? rest) |
164 | (let mapf ((l l)) | |
165 | (or (null? l) | |
166 | (and (pred (car l)) (mapf (cdr l)))))) | |
167 | (else (let mapf ((l l) (rest rest)) | |
168 | (or (null? l) | |
169 | (and (apply pred (car l) (map car rest)) | |
170 | (mapf (cdr l) (map cdr rest)))))))) | |
171 | ||
c771038b | 172 | (define-public (notany pred . ls) |
16693054 | 173 | "Return #t iff every application of PRED to L, etc., returns #f. |
59dd1852 MV |
174 | Analogous to some but returns #t if no application of PRED returns a |
175 | true value or #f as soon as any one does." | |
16693054 GB |
176 | (not (apply some pred ls))) |
177 | ||
c771038b | 178 | (define-public (notevery pred . ls) |
16693054 GB |
179 | "Return #t iff there is an application of PRED to L, etc., that returns #f. |
180 | Analogous to some but returns #t as soon as an application of PRED returns #f, | |
181 | or #f otherwise." | |
182 | (not (apply every pred ls))) | |
183 | ||
d69947f7 | 184 | (define-public (count-if pred l) |
c771038b | 185 | "Return the number of elements in L for which (PRED element) returns true." |
d69947f7 KN |
186 | (let loop ((n 0) (l l)) |
187 | (cond ((null? l) n) | |
188 | ((pred (car l)) (loop (+ n 1) (cdr l))) | |
189 | (else (loop n (cdr l)))))) | |
190 | ||
16693054 | 191 | (define-public (find-if pred l) |
c771038b TTN |
192 | "Search for the first element in L for which (PRED element) returns true. |
193 | If found, return that element, otherwise return #f." | |
a6401ee0 | 194 | (cond ((null? l) #f) |
16693054 GB |
195 | ((pred (car l)) (car l)) |
196 | (else (find-if pred (cdr l))))) | |
a6401ee0 | 197 | |
16693054 | 198 | (define-public (member-if pred l) |
abf94ef3 | 199 | "Return the first sublist of L for whose car PRED is true." |
a6401ee0 | 200 | (cond ((null? l) #f) |
16693054 GB |
201 | ((pred (car l)) l) |
202 | (else (member-if pred (cdr l))))) | |
a6401ee0 | 203 | |
c771038b TTN |
204 | (define-public (remove-if pred l) |
205 | "Remove all elements from L where (PRED element) is true. | |
206 | Return everything that's left." | |
e5d2c2fa DH |
207 | (let loop ((l l) (result '())) |
208 | (cond ((null? l) (reverse! result)) | |
45cf8cd6 | 209 | ((pred (car l)) (loop (cdr l) result)) |
e5d2c2fa | 210 | (else (loop (cdr l) (cons (car l) result)))))) |
a6401ee0 | 211 | |
c771038b TTN |
212 | (define-public (remove-if-not pred l) |
213 | "Remove all elements from L where (PRED element) is #f. | |
214 | Return everything that's left." | |
e5d2c2fa DH |
215 | (let loop ((l l) (result '())) |
216 | (cond ((null? l) (reverse! result)) | |
45cf8cd6 | 217 | ((not (pred (car l))) (loop (cdr l) result)) |
e5d2c2fa | 218 | (else (loop (cdr l) (cons (car l) result)))))) |
16693054 | 219 | |
e5d2c2fa | 220 | (define-public (delete-if! pred l) |
16693054 | 221 | "Destructive version of `remove-if'." |
e5d2c2fa DH |
222 | (let delete-if ((l l)) |
223 | (cond ((null? l) '()) | |
224 | ((pred (car l)) (delete-if (cdr l))) | |
a6401ee0 | 225 | (else |
e5d2c2fa | 226 | (set-cdr! l (delete-if (cdr l))) |
c771038b | 227 | l)))) |
a6401ee0 | 228 | |
e5d2c2fa | 229 | (define-public (delete-if-not! pred l) |
16693054 | 230 | "Destructive version of `remove-if-not'." |
e5d2c2fa DH |
231 | (let delete-if-not ((l l)) |
232 | (cond ((null? l) '()) | |
233 | ((not (pred (car l))) (delete-if-not (cdr l))) | |
a6401ee0 | 234 | (else |
e5d2c2fa DH |
235 | (set-cdr! l (delete-if-not (cdr l))) |
236 | l)))) | |
a6401ee0 JB |
237 | |
238 | (define-public (butlast lst n) | |
16693054 | 239 | "Return all but the last N elements of LST." |
a6401ee0 JB |
240 | (letrec ((l (- (length lst) n)) |
241 | (bl (lambda (lst n) | |
242 | (cond ((null? lst) lst) | |
243 | ((positive? n) | |
244 | (cons (car lst) (bl (cdr lst) (+ -1 n)))) | |
245 | (else '()))))) | |
246 | (bl lst (if (negative? n) | |
247 | (error "negative argument to butlast" n) | |
248 | l)))) | |
249 | ||
250 | (define-public (and? . args) | |
59dd1852 | 251 | "Return #t iff all of ARGS are true." |
a6401ee0 JB |
252 | (cond ((null? args) #t) |
253 | ((car args) (apply and? (cdr args))) | |
254 | (else #f))) | |
255 | ||
256 | (define-public (or? . args) | |
59dd1852 | 257 | "Return #t iff any of ARGS is true." |
a6401ee0 JB |
258 | (cond ((null? args) #f) |
259 | ((car args) #t) | |
260 | (else (apply or? (cdr args))))) | |
261 | ||
262 | (define-public (has-duplicates? lst) | |
16693054 | 263 | "Return #t iff 2 members of LST are equal?, else #f." |
a6401ee0 JB |
264 | (cond ((null? lst) #f) |
265 | ((member (car lst) (cdr lst)) #t) | |
266 | (else (has-duplicates? (cdr lst))))) | |
267 | ||
a6401ee0 | 268 | (define-public (pick p l) |
16693054 GB |
269 | "Apply P to each element of L, returning a list of elts |
270 | for which P returns a non-#f value." | |
a6401ee0 JB |
271 | (let loop ((s '()) |
272 | (l l)) | |
273 | (cond | |
274 | ((null? l) s) | |
275 | ((p (car l)) (loop (cons (car l) s) (cdr l))) | |
276 | (else (loop s (cdr l)))))) | |
277 | ||
a6401ee0 | 278 | (define-public (pick-mappings p l) |
c771038b | 279 | "Apply P to each element of L, returning a list of the |
16693054 | 280 | non-#f return values of P." |
a6401ee0 JB |
281 | (let loop ((s '()) |
282 | (l l)) | |
283 | (cond | |
284 | ((null? l) s) | |
285 | ((p (car l)) => (lambda (mapping) (loop (cons mapping s) (cdr l)))) | |
286 | (else (loop s (cdr l)))))) | |
287 | ||
288 | (define-public (uniq l) | |
16693054 | 289 | "Return a list containing elements of L, with duplicates removed." |
23d91908 MV |
290 | (let loop ((acc '()) |
291 | (l l)) | |
292 | (if (null? l) | |
293 | (reverse! acc) | |
294 | (loop (if (memq (car l) acc) | |
295 | acc | |
296 | (cons (car l) acc)) | |
297 | (cdr l))))) | |
c771038b TTN |
298 | |
299 | ;;; common-list.scm ends here |