From 0044d86271c15615ff0ce984de37be57cb677575 Mon Sep 17 00:00:00 2001 From: Sam Tobin-Hochstadt Date: Thu, 7 Jan 2010 19:10:43 +0000 Subject: [PATCH] fix extend to handle negative lengths svn: r17540 --- collects/unstable/list.ss | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/collects/unstable/list.ss b/collects/unstable/list.ss index 661721467a..f8609a42c4 100644 --- a/collects/unstable/list.ss +++ b/collects/unstable/list.ss @@ -33,7 +33,7 @@ ;; Listof[A] Listof[B] B -> Listof[B] ;; pads out t to be as long as s (define (extend s t extra) - (append t (build-list (- (length s) (length t)) (lambda _ extra)))) + (append t (build-list (max 0 (- (length s) (length t))) (lambda _ extra)))) (provide filter-multiple extend)