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authorKaz Kylheku <kaz@kylheku.com>2019-09-10 20:00:16 -0700
committerKaz Kylheku <kaz@kylheku.com>2019-09-10 20:00:16 -0700
commitd3d92b3c4e24fb296b124ba18e01442783da7fa7 (patch)
treefc8fbccd2efa397c52998b23a81cd0d252c0523e
parenta615af8eff76e33bb5bd4dcd591d2857096f6258 (diff)
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list-builder: simplify circularity check in pend.
* share/txr/stdlib/build.tl (list-builder pend): Use tailp instead of last and eq.
-rw-r--r--share/txr/stdlib/build.tl5
1 files changed, 1 insertions, 4 deletions
diff --git a/share/txr/stdlib/build.tl b/share/txr/stdlib/build.tl
index c607571f..76be9f55 100644
--- a/share/txr/stdlib/build.tl
+++ b/share/txr/stdlib/build.tl
@@ -49,10 +49,7 @@
(let ((st self.tail))
(rplacd st (append (cdr st) nil)))
(let* ((tl (last self.tail))
- (cp (let ((ll (car (last lists))))
- (if (consp ll)
- (let ((lt (last ll)))
- (eq tl lt)))))
+ (cp (tailp tl (car (last lists))))
(nl [apply append lists]))
(usr:rplacd tl (append (cdr tl) (if cp (copy-list nl) nl)))
(set self.tail tl))