From 03f8ca5d79e2dd98a4f511b7a550ce00991f60e6 Mon Sep 17 00:00:00 2001 From: Matthew Butterick Date: Fri, 8 Apr 2022 14:07:47 -0700 Subject: [PATCH] comment --- quad2/attr.rkt | 3 +++ 1 file changed, 3 insertions(+) diff --git a/quad2/attr.rkt b/quad2/attr.rkt index 94dba33d..51728185 100644 --- a/quad2/attr.rkt +++ b/quad2/attr.rkt @@ -13,6 +13,9 @@ (provide (all-defined-out)) (define (for-each-attrs xs proc) + ;; apply `proc` to each set of attrs in `xs`. + ;; recursively descend from top to bottom. + ;; but also track which attrs are visited and skip any already visited. (define attrs-seen (mutable-seteq)) (let loop ([xs xs][parent-attrs #false]) (for ([x (in-list xs)]