gcl.git - GNU Common Lisp

diff --git a/gcl/lsp/gcl_listlib.lsp b/gcl/lsp/gcl_listlib.lsp
index 914fbf8e2..d12c3bfe0 100644
--- a/gcl/lsp/gcl_listlib.lsp
+++ b/gcl/lsp/gcl_listlib.lsp

@@ -371,7 +371,8 @@

(defseq union (nil (l1 l2) :list t)

(let (rp)

- (prog1 (or (mapcan (lambda (x)

+ (prog1 (or (unless l2 l1)

+ (mapcan (lambda (x)

(unless (member (key x) l2 :test #'test)

(setq rp (cons x nil))))

l1)

@@ -380,21 +381,26 @@

(defseq set-difference (nil (l1 l2) :list t)

- (mapcan (lambda (x)

+ (if l2

+ (mapcan (lambda (x)

(unless (member (key x) l2 :test #'test)

(cons x nil)))

- l1))

+ l1)

+ l1))

(defseq set-exclusive-or (nil (l1 l2) :list t)

- (let (rp (rr (copy-list l2)))

- (prog1 (or (mapcan (lambda (x &aux (k (key x)))

+ (let (rp tmp n2)

+ (declare (dynamic-extent tmp))

+ (or (unless l2 l1)

+ (prog1 (mapcan (lambda (x &aux (k (key x)))

(if (member k l2 :test #'test)

- (unless (setq rr (delete k rr :test #'test)))

+ (unless (push k tmp))

(setq rp (cons x nil))))

l1)

- rr)

- (when rp (rplacd rp rr)))))

+ (setq n2 (set-difference l2 tmp :test (lambda (x y) (funcall #'test y x))))

+ (when rp (rplacd rp n2)))

+ n2)))

(defseq nintersection (nil (l1 l2) :list t)

(let (r rp)