;;;; common-list.scm --- COMMON LISP list functions for Scheme
;;;;
-;;;; Copyright (C) 1995, 1996, 1997 Free Software Foundation, Inc.
-;;;;
+;;;; Copyright (C) 1995, 1996, 1997, 2001 Free Software Foundation, Inc.
+;;;;
;;;; This program is free software; you can redistribute it and/or modify
;;;; it under the terms of the GNU General Public License as published by
;;;; the Free Software Foundation; either version 2, or (at your option)
;;;; any later version.
-;;;;
+;;;;
;;;; This program is distributed in the hope that it will be useful,
;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;;;; GNU General Public License for more details.
-;;;;
+;;;;
;;;; You should have received a copy of the GNU General Public License
;;;; along with this software; see the file COPYING. If not, write to
;;;; the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
;;;; Boston, MA 02111-1307 USA
-;;;;
+;;;;
+;;;; As a special exception, the Free Software Foundation gives permission
+;;;; for additional uses of the text contained in its release of GUILE.
+;;;;
+;;;; The exception is that, if you link the GUILE library with other files
+;;;; to produce an executable, this does not by itself cause the
+;;;; resulting executable to be covered by the GNU General Public License.
+;;;; Your use of that executable is in no way restricted on account of
+;;;; linking the GUILE library code into it.
+;;;;
+;;;; This exception does not however invalidate any other reasons why
+;;;; the executable file might be covered by the GNU General Public License.
+;;;;
+;;;; This exception applies only to the code released by the
+;;;; Free Software Foundation under the name GUILE. If you copy
+;;;; code from other Free Software Foundation releases into a copy of
+;;;; GUILE, as the General Public License permits, the exception does
+;;;; not apply to the code that you add in this way. To avoid misleading
+;;;; anyone as to the status of such modified files, you must delete
+;;;; this exception notice from them.
+;;;;
+;;;; If you write modifications of your own for GUILE, it is your choice
+;;;; whether to permit this exception to apply to your modifications.
+;;;; If you do not wish that, delete this exception notice.
+;;;;
+
+;;; Commentary:
+
+;; These procedures are exported:
+;; (adjoin e l)
+;; (union l1 l2)
+;; (intersection l1 l2)
+;; (set-difference l1 l2)
+;; (reduce-init p init l)
+;; (reduce p l)
+;; (some pred l . rest)
+;; (every pred l . rest)
+;; (notany pred . ls)
+;; (notevery pred . ls)
+;; (count-if pred l)
+;; (find-if pred l)
+;; (member-if pred l)
+;; (remove-if pred l)
+;; (remove-if-not pred l)
+;; (delete-if! pred l)
+;; (delete-if-not! pred l)
+;; (butlast lst n)
+;; (and? . args)
+;; (or? . args)
+;; (has-duplicates? lst)
+;; (pick p l)
+;; (pick-mappings p l)
+;; (uniq l)
+;;
+;; See docstrings for each procedure for more info. See also module
+;; `(srfi srfi-1)' for a complete list handling library.
+
+;;; Code:
\f
-(define-module (ice-9 common-list))
+(define-module (ice-9 common-list)
+ :export (adjoin union intersection set-difference reduce-init reduce
+ some every notany notevery count-if find-if member-if remove-if
+ remove-if-not delete-if! delete-if-not! butlast and? or?
+ has-duplicates? pick pick-mappings uniq))
;;"comlist.scm" Implementation of COMMON LISP list functions for Scheme
; Copyright (C) 1991, 1993, 1995 Aubrey Jaffer.
;promotional, or sales literature without prior written consent in
;each case.
-(define-public (adjoin e l)
- "Returns list L, possibly with element E added if it is not already in L."
+(define (adjoin e l)
+ "Return list L, possibly with element E added if it is not already in L."
(if (memq e l) l (cons e l)))
-(define-public (union l1 l2)
- "Returns a new list that is the union of L1 and L2.
-Elements that occur in both lists will occur only once
-in the result list."
+(define (union l1 l2)
+ "Return a new list that is the union of L1 and L2.
+Elements that occur in both lists occur only once in
+the result list."
(cond ((null? l1) l2)
((null? l2) l1)
(else (union (cdr l1) (adjoin (car l1) l2)))))
-(define-public (intersection l1 l2)
- "Returns a new list that is the intersection of L1 and L2.
-Only elements that occur in both lists will occur in the result list."
- (cond ((null? l1) l1)
- ((null? l2) l2)
- ((memv (car l1) l2) (cons (car l1) (intersection (cdr l1) l2)))
- (else (intersection (cdr l1) l2))))
+(define (intersection l1 l2)
+ "Return a new list that is the intersection of L1 and L2.
+Only elements that occur in both lists occur in the result list."
+ (if (null? l2) l2
+ (let loop ((l1 l1) (result '()))
+ (cond ((null? l1) (reverse! result))
+ ((memv (car l1) l2) (loop (cdr l1) (cons (car l1) result)))
+ (else (loop (cdr l1) result))))))
-(define-public (set-difference l1 l2)
+(define (set-difference l1 l2)
"Return elements from list L1 that are not in list L2."
- (cond ((null? l1) l1)
- ((memv (car l1) l2) (set-difference (cdr l1) l2))
- (else (cons (car l1) (set-difference (cdr l1) l2)))))
+ (let loop ((l1 l1) (result '()))
+ (cond ((null? l1) (reverse! result))
+ ((memv (car l1) l2) (loop (cdr l1) result))
+ (else (loop (cdr l1) (cons (car l1) result))))))
-(define-public (reduce-init p init l)
+(define (reduce-init p init l)
"Same as `reduce' except it implicitly inserts INIT at the start of L."
(if (null? l)
init
(reduce-init p (p init (car l)) (cdr l))))
-(define-public (reduce p l)
- "Combines all the elements of sequence L using a binary operation P.
-The combination is left-associative. For example, using +, one can
-add up all the elements. `reduce' allows you to apply a function which
+(define (reduce p l)
+ "Combine all the elements of sequence L using a binary operation P.
+The combination is left-associative. For example, using +, one can
+add up all the elements. `reduce' allows you to apply a function which
accepts only two arguments to more than 2 objects. Functional
programmers usually refer to this as foldl."
(cond ((null? l) l)
((null? (cdr l)) (car l))
(else (reduce-init p (car l) (cdr l)))))
-(define-public (some pred l . rest)
+(define (some pred l . rest)
"PRED is a boolean function of as many arguments as there are list
-arguments to `some'. I.e., L plus any optional arguments. PRED is
-applied to successive elements of the list arguments in order. As soon
-as one of these applications returns a true value, `some' terminates
-and returns that value. If no application returns a true value,
-`some' returns #f. All the lists should have the same length."
+arguments to `some', i.e., L plus any optional arguments. PRED is
+applied to successive elements of the list arguments in order. As soon
+as one of these applications returns a true value, return that value.
+If no application returns a true value, return #f.
+All the lists should have the same length."
(cond ((null? rest)
(let mapf ((l l))
(and (not (null? l))
(or (apply pred (car l) (map car rest))
(mapf (cdr l) (map cdr rest))))))))
-(define-public (every pred l . rest)
+(define (every pred l . rest)
"Return #t iff every application of PRED to L, etc., returns #t.
Analogous to `some' except it returns #t if every application of
PRED is #t and #f otherwise."
(and (apply pred (car l) (map car rest))
(mapf (cdr l) (map cdr rest))))))))
-(define-public (notany pred . ls)
+(define (notany pred . ls)
"Return #t iff every application of PRED to L, etc., returns #f.
Analogous to some but returns #t if no application of PRED returns a
true value or #f as soon as any one does."
(not (apply some pred ls)))
-(define-public (notevery pred . ls)
+(define (notevery pred . ls)
"Return #t iff there is an application of PRED to L, etc., that returns #f.
Analogous to some but returns #t as soon as an application of PRED returns #f,
or #f otherwise."
(not (apply every pred ls)))
-(define-public (find-if pred l)
- "Searches for the first element in L such that (PRED element)
-returns true. If it finds any such element in L, element is
-returned. Otherwise, #f is returned."
+(define (count-if pred l)
+ "Return the number of elements in L for which (PRED element) returns true."
+ (let loop ((n 0) (l l))
+ (cond ((null? l) n)
+ ((pred (car l)) (loop (+ n 1) (cdr l)))
+ (else (loop n (cdr l))))))
+
+(define (find-if pred l)
+ "Search for the first element in L for which (PRED element) returns true.
+If found, return that element, otherwise return #f."
(cond ((null? l) #f)
((pred (car l)) (car l))
(else (find-if pred (cdr l)))))
-(define-public (member-if pred l)
- "Returns L if (T element) is true for any element in L. Returns #f
-if PRED does not apply to any element in L."
+(define (member-if pred l)
+ "Return the first sublist of L for whose car PRED is true."
(cond ((null? l) #f)
((pred (car l)) l)
(else (member-if pred (cdr l)))))
-(define-public (remove-if p l)
- "Removes all elements from L where (P element) is true.
-Returns everything that's left."
- (cond ((null? l) '())
- ((p (car l)) (remove-if p (cdr l)))
- (else (cons (car l) (remove-if p (cdr l))))))
-
-(define-public (remove-if-not p l)
- "Removes all elements from L where (P element) is #f.
-Returns everything that's left."
- (cond ((null? l) '())
- ((not (p (car l))) (remove-if-not p (cdr l)))
- (else (cons (car l) (remove-if-not p (cdr l))))))
-
-(define-public (delete-if! pred list)
+(define (remove-if pred l)
+ "Remove all elements from L where (PRED element) is true.
+Return everything that's left."
+ (let loop ((l l) (result '()))
+ (cond ((null? l) (reverse! result))
+ ((pred (car l)) (loop (cdr l) result))
+ (else (loop (cdr l) (cons (car l) result))))))
+
+(define (remove-if-not pred l)
+ "Remove all elements from L where (PRED element) is #f.
+Return everything that's left."
+ (let loop ((l l) (result '()))
+ (cond ((null? l) (reverse! result))
+ ((not (pred (car l))) (loop (cdr l) result))
+ (else (loop (cdr l) (cons (car l) result))))))
+
+(define (delete-if! pred l)
"Destructive version of `remove-if'."
- (let delete-if ((list list))
- (cond ((null? list) '())
- ((pred (car list)) (delete-if (cdr list)))
+ (let delete-if ((l l))
+ (cond ((null? l) '())
+ ((pred (car l)) (delete-if (cdr l)))
(else
- (set-cdr! list (delete-if (cdr list)))
- list))))
+ (set-cdr! l (delete-if (cdr l)))
+ l))))
-(define-public (delete-if-not! pred list)
+(define (delete-if-not! pred l)
"Destructive version of `remove-if-not'."
- (let delete-if ((list list))
- (cond ((null? list) '())
- ((not (pred (car list))) (delete-if-not (cdr list)))
+ (let delete-if-not ((l l))
+ (cond ((null? l) '())
+ ((not (pred (car l))) (delete-if-not (cdr l)))
(else
- (set-cdr! list (delete-if-not (cdr list)))
- list))))
+ (set-cdr! l (delete-if-not (cdr l)))
+ l))))
-(define-public (butlast lst n)
+(define (butlast lst n)
"Return all but the last N elements of LST."
(letrec ((l (- (length lst) n))
(bl (lambda (lst n)
(error "negative argument to butlast" n)
l))))
-(define-public (and? . args)
+(define (and? . args)
"Return #t iff all of ARGS are true."
(cond ((null? args) #t)
((car args) (apply and? (cdr args)))
(else #f)))
-(define-public (or? . args)
+(define (or? . args)
"Return #t iff any of ARGS is true."
(cond ((null? args) #f)
((car args) #t)
(else (apply or? (cdr args)))))
-(define-public (has-duplicates? lst)
+(define (has-duplicates? lst)
"Return #t iff 2 members of LST are equal?, else #f."
(cond ((null? lst) #f)
((member (car lst) (cdr lst)) #t)
(else (has-duplicates? (cdr lst)))))
-(define-public (list* x . y)
- "Works like `list' except that the cdr of the last pair is
-the last argument unless there is only one argument, when
-th result is just that argument. Sometiems called cons*."
- (define (list*1 x)
- (if (null? (cdr x))
- (car x)
- (cons (car x) (list*1 (cdr x)))))
- (if (null? y)
- x
- (cons x (list*1 y))))
-
-(define-public (pick p l)
+(define (pick p l)
"Apply P to each element of L, returning a list of elts
for which P returns a non-#f value."
(let loop ((s '())
((p (car l)) (loop (cons (car l) s) (cdr l)))
(else (loop s (cdr l))))))
-(define-public (pick-mappings p l)
- "Apply P to each element of L, returning a list of the
+(define (pick-mappings p l)
+ "Apply P to each element of L, returning a list of the
non-#f return values of P."
(let loop ((s '())
(l l))
((p (car l)) => (lambda (mapping) (loop (cons mapping s) (cdr l))))
(else (loop s (cdr l))))))
-(define-public (uniq l)
+(define (uniq l)
"Return a list containing elements of L, with duplicates removed."
- (if (null? l)
- '()
- (let ((u (uniq (cdr l))))
- (if (memq (car l) u)
- u
- (cons (car l) u)))))
+ (let loop ((acc '())
+ (l l))
+ (if (null? l)
+ (reverse! acc)
+ (loop (if (memq (car l) acc)
+ acc
+ (cons (car l) acc))
+ (cdr l)))))
+;;; common-list.scm ends here
HCoop / bpt / guile.git / blobdiff