From e50f229beb2cc9e164b2aea422f83a560bbb832f Mon Sep 17 00:00:00 2001 From: Matthias Felleisen Date: Tue, 22 Jul 2008 21:00:07 +0000 Subject: [PATCH] scene fixed in world svn: r10863 --- collects/teachpack/htdp/scribblings/world.scrbl | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/collects/teachpack/htdp/scribblings/world.scrbl b/collects/teachpack/htdp/scribblings/world.scrbl index a4760e620d..68614a12d3 100644 --- a/collects/teachpack/htdp/scribblings/world.scrbl +++ b/collects/teachpack/htdp/scribblings/world.scrbl @@ -21,9 +21,12 @@ The teachpack assumes working knowledge of the basic image manipulation primitives and introduces a special kind of image: a scene. @deftech{Scene}@; -@schemeblock[(and/c image? - (lambda (i) - (and (= (pinhole-x i) 0) (= (pinhole-y i) 0))))] +@schemeblock[ +;; Image -> Boolean +(define (focus-at-0-0 i) + (and (= (pinhole-x i) 0) (= (pinhole-y i) 0))) + +(and/c image? focus-at-0-0)] The teachpack can display only @tech{Scene}s, which are images whose pinholes are at position @scheme[(0,0)].