From f6f6facd9e8b667e780e070ec7b915c51e8897cb Mon Sep 17 00:00:00 2001 From: Matthew Flatt Date: Fri, 10 Dec 2010 12:45:18 -0700 Subject: [PATCH] clarify effective-constant nature of `list?' Closes PR 11525 --- collects/scribblings/reference/pairs.scrbl | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/collects/scribblings/reference/pairs.scrbl b/collects/scribblings/reference/pairs.scrbl index 74e08fa780..2c83be868b 100644 --- a/collects/scribblings/reference/pairs.scrbl +++ b/collects/scribblings/reference/pairs.scrbl @@ -153,7 +153,10 @@ null @defproc[(list? [v any/c]) boolean?]{Returns @scheme[#t] if @scheme[v] is a list: either the empty list, or a pair whose second element is a - list. This procedure takes amortized constant time. + list. This procedure effectively takes constant time due to internal caching + (so that any necessary traversals of pairs can in principle count as an + extra cost of allocating the pairs). + @mz-examples[ (list? '(1 2)) (list? (cons 1 (cons 2 '())))