Import Upstream version 2c7upstream/2c7

1 files changed, 16 insertions, 6 deletions

diff --git a/comlist.scm b/comlist.scm
index 1751c7f..8ecf525 100644
--- a/comlist.scm
+++ b/comlist.scm
@@ -31,7 +31,7 @@
 
 (define (comlist:copy-list lst) (append lst '()))
 
-(define (comlist:adjoin e l) (if (memq e l) l (cons e l)))
+(define (comlist:adjoin e l) (if (memv e l) l (cons e l)))
 
 (define (comlist:union l1 l2)
   (cond ((null? l1) l2)
@@ -176,13 +176,22 @@
 	((car args) #t)
 	(else (apply comlist:or? (cdr args)))))
 
-; Checks to see if a list has any duplicates.
+;;; Checks to see if a list has any duplicate MEMBERs.
 (define (comlist:has-duplicates? lst)
   (cond ((null? lst) #f)
 	((member (car lst) (cdr lst)) #t)
 	(else (comlist:has-duplicates? (cdr lst)))))
 
-(define (comlist:list* x . y)	
+;;; remove duplicates of MEMBERs of a list
+(define (comlist:remove-duplicates lst)
+  (letrec ((rem-dup
+	    (lambda (lst nlst)
+	      (cond ((null? lst) nlst)
+		    ((member (car lst) nlst) (rem-dup (cdr lst) nlst))
+		    (else (rem-dup (cdr lst) (cons (car lst) nlst)))))))
+    (rem-dup lst '())))
+
+(define (comlist:list* x . y)
   (define (list*1 x)
     (if (null? (cdr x))
 	(car x)
@@ -283,7 +292,7 @@
 	  ((equal? obj (car list)) (delete (cdr list)))
 	  (else
 	   (set-cdr! list (delete (cdr list)))
-	   list)))) 
+	   list))))
 
 (define (comlist:delete-if pred list)
   (let delete-if ((list list))
@@ -291,7 +300,7 @@
 	  ((pred (car list)) (delete-if (cdr list)))
 	  (else
 	   (set-cdr! list (delete-if (cdr list)))
-	   list)))) 
+	   list))))
 
 (define (comlist:delete-if-not pred list)
   (let delete-if ((list list))
@@ -299,7 +308,7 @@
 	  ((not (pred (car list))) (delete-if (cdr list)))
 	  (else
 	   (set-cdr! list (delete-if (cdr list)))
-	   list)))) 
+	   list))))
 
 ;;; exports
 
@@ -330,6 +339,7 @@
 (define and? comlist:and?)
 (define or? comlist:or?)
 (define has-duplicates? comlist:has-duplicates?)
+(define remove-duplicates comlist:remove-duplicates)
 
 (define delete-if-not comlist:delete-if-not)
 (define delete-if comlist:delete-if)