This sounds ideal. I'll check it out. <div class="gmail_quote">On Nov 28, 2012 8:00 AM, "Matthew Flatt" <<a href="mailto:mflatt@cs.utah.edu">mflatt@cs.utah.edu</a>> wrote: <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> For what it's worth <a href="https://github.com/mflatt/scratchy" target="_blank">https://github.com/mflatt/scratchy</a> is an implementation of the Scratch sprite and evaluation model plus a textual language. It has all of the drawbacks of Scratch --- mutation, race conditions, and busy waiting --- without the nice graphical syntax! It has a collision detector that's much like John's, but I spent some time making it go faster. There's also a notion of "lands" within a program. I wrote Scratchy as an example of building languages in Racket for this year's RacketCon.[*] I dream about a phase 2 where I figure out how to change the evaluation model to something good and/or connect with `2htdp/universe', but I don't see that happening soon. [*] At the suggestion of my son. He's a Scratch fan, though he quickly became frustrated by the lack of abstraction in Scratch, and I don't know whether to be happy or sad that he's a 12-year-old who understands the phrase "race condition". Scratchy has "lands" because he wanted something like that for his game. At Wed, 28 Nov 2012 07:37:27 -0500, Yaron Minsky wrote: > To be clear, I'm firmly interested in tinkering, which is why I'm > using universe.ss and image.ss. > > I do think that a good design goal for Racket's kid-oriented libraries > would be to be feature compatible with Scratch. It would be great if > there were good ways of doing everything that Scratch can do, from > playing sounds to detecting collisions, to (more aggressively) on-line > hosting of the final result. I'd love it if Racket were strictly > better than Scratch for someone who really can figure out how to > program, but it's just not true now. > > y > > On Wed, Nov 28, 2012 at 7:11 AM, Hendrik Boom <<a href="mailto:hendrik@topoi.pooq.com">hendrik@topoi.pooq.com</a>> wrote: > > On Tue, Nov 27, 2012 at 08:56:13PM -0500, Yaron Minsky wrote: > >> I've been weaning my son off of Scratch in favor of Racket, and trying > >> to get him to write interactive games using universe.ss and image.ss. > >> I'm wondering if anyone has suggestions for how to do things like > >> collision detection. image.ss has these nice first-class images, but > >> I don't see a good way of querying two images to see if they overlap. > >> > >> Has anyone else had luck in doing this? universe has a nice > >> programming model, but I've found it challenging to find simple ways > >> of doing the kinds of things that Scratch makes easy. > > > > There are two arts to collision detection: figuring out whether two > > images collide (which gets trickier when they're in motion) and > > organising all your objects so you don't have to test very many > > combinations of them. > > > > Both of these can get quite complicated, and are susceptible to > > nontrivial, complicated, and often necessary efficiency improvements > > depending on special properties of the game. > > > > A one-size-fits-all solution may be good enough for tinkering with, but > > serious use may well need serious hacking. > > > > -- hendrik > > ____________________ > > Racket Users list: > > <a href="http://lists.racket-lang.org/users" target="_blank">http://lists.racket-lang.org/users</a> > ____________________ > Racket Users list: > <a href="http://lists.racket-lang.org/users" target="_blank">http://lists.racket-lang.org/users</a> </blockquote></div>