Show HN: My current App Store Featured Game was written entirely in Scheme

https://itunes.apple.com/us/app/cloud-breaker/id721767500?mt=8

by rrradical • 12 years ago

290 110 12 years ago

itunes.apple.com

rrradical16• 12 years ago

I'm the author. I wrote the game and engine using the wonderful, and fast, Gambit Scheme (http://gambitscheme.org/).

I needed a lisp to manipulate the puzzles, because they aren't based in a strict grid. It ended up being way more natural to program the block structures as lists rather than traditional matrices.

Gambit compiles the Scheme code down to C, which I can then link to Objective-C for iOS, or port to Android or any other platform that Gambit supports.

anuragramdasan2• 12 years ago

My lisp experience has been largely restricted to writing elisp. I would really love to write something in Scheme though. How well maintained and diverse are the GambitScheme libraries? I see three different sets on their packages page, do you have any experience with those or would you have some better suggestions?

rrradical16• 12 years ago

I didn't use many libraries. It's pretty straightforward to interface with C code, so instead of writing a whole OpenGL wrapper, I just call into some C code to handle the rendering.

It was somewhat tricky to get it all setup, but I followed in the footsteps of James Long (http://jlongster.com/s/jlongster-old/pages/blog/write-apps-i...) and a few others.

I hope to contribute back what I learned and make it easier for others to use it for games in the future. It's seriously a great language for game writing.

Touche• 12 years ago

How well maintained and diverse are the GambitScheme libraries?

The library situation in Gambit is.... very bad. Last time I tried it (~6 months ago) you had to compile from a different branch to get Blackhole to work.

Chicken Scheme has a much better ecosystem. It also compiles to C and is fast. Gambit is known for its speed so I won't say Chicken is as fast but it is "fast enough" and the ecosystem is worth the difference IMO.

npsimons5• 12 years ago

Thanks for posting this, but the link is rather anemic for this audience; any possibility of a writeup (even a quick and short one) of how you did it? I've been looking at cross-platform solutions for apps, and the best I've come up with so far is Kivy (http://kivy.org) and haXe (http://haxe.org), which both still require a machine running OSX to package for iOS.

rrradical16• 12 years ago

Thanks, that's a good point. I am definitely planning on writing up everything I learned in the process. It just launched a few days ago so I'm still focused on handling that at the moment.

If you like I can e-mail you in the future when the article is out. There's contact info on my website: http://asivitz.com/cloudbreaker/

sogen• 12 years ago

for HTML5, check out Cordova, even Adobe offers a free iOS / Android / Win8 compiler

tvon• 12 years ago

I could be mistaken (as I haven't actually researched this), but I don't think there is any way around needing OSX to package for iOS. Even tools like cordova/phonegap hook into a base Xcode project when it comes to compiling and packaging.

TuringTest• 12 years ago

Oh? How do you traverse vertical and horizontal structures that are wider than one block? If you have vertical lists, following a horizontal row wild involve lots of find-nth-position calls, which I wouldn't call "natural"

rrradical16• 12 years ago

The basic data structure is this

((0 (73 84 92)) (1 (17 95 31)))

Where the 2 digit numbers are id numbers for the blocks. The single digit number to left of each row is the horizontal offset.

So, shifting a row, the most elementary operation in the game, just requires incrementing the offset.

Vertical shifts are done with a 90 degree rotation operation, then a horizontal shift, then a -90 degree rotation.

Sometimes traversing the lists is necessary, but the most common operations are fast, and then rest are fast enough.

The limiting factor in performance is definitely rendering, not the game logic.

mcescalante• 12 years ago

Since you mentioned it, I'd love (to download & play) a port to Android at some point :)

rrradical16• 12 years ago

Thanks! I'm planning on releasing for Android soon. Hopefully in the next month or two.

moron4hire• 12 years ago

Any chance you'd write a technical article on your algorithms? I'm in love with puzzle manipulation code. Seeing the sort of things you're doing would be a lot of fun.

rrradical16• 12 years ago

Yea, I'd love to write about some of that stuff. There's unfortunately a big problem with indie games getting cloned out of existence by some big publishers, so I'm a little hesitant to put all of the logic out there. I do think it would be pretty hard to implement in a traditional OO language though.

There's a basic explanation of the method in another comment I've written here though.

jorgeleo• 12 years ago

Awesome work in so many ways. Congratulations!

orthecreedence• 12 years ago

Would really like an end-to-end guide on compiling C with objective C (and possibly some example code in gambit that shows the interfacing you did).

I'd love to be able to do this with ECL (http://ecls.sourceforge.net/) to build apps in common lisp for iOS (possibly android). I know about MOCL, but I'm a pretty cheap guy, so would rather stick to open technologies and do the work myself.

I'm not a scheme guy, but until you get a writeup done, would you mind posting any info you have on interfacing gambit with iOS?

Good work, and thanks for sharing!!

funcall• 12 years ago

I did an ECL port to iOS a while back, which you can read about in the ecl links here:

http://kriyative.github.io/tags/

I vaguely remember someone adapting it with an ECL to android cross compilation effort. Can't find that link now.

The LGPL license of ECL is something to keep in mind as you consider your options.

Good luck.

rrradical16• 12 years ago

The standard Gambit distribution actually comes with an example iOS project. It also has a script for building the Gambit runtime for ARM (the phone) and x86.

It's definitely not a 10 minute process, but shouldn't be too hard.

I think I also remember some projects popping up the Gambit mailing list to make all of this easier. It might be worth searching the archives.

chm3• 12 years ago

As soon as I saw the game, I thought about Gambit-C. I'm currently following a compiler class with its author.

j_m_b2• 12 years ago

I'm currently following a compiler class with its author.

Is this an online source? I would love to see a compiler course by someone like Marc Feeley!

seivan• 12 years ago

I am so jealous and incredibly happy that you shipped - nice work. I wish I could do that as well.

rrradical16• 12 years ago

Thank you! No time like the present to start. Just do your best and then keep redefining what your best is.

jlongster6• 12 years ago

Awesome work! I'm continually blown away that people still reference my old work on porting Gambit Scheme for iOS.

Almost makes me want to play around with it again. :)

rrradical16• 12 years ago

Yes! So glad you saw this!

I had trouble getting the server based repl working, so here's the in-game repl I ended up implementing as a Quake-type dev console: http://imgur.com/J6ozzT6

(Obviously disabled in the App Store version.)

I may be getting ahead of myself, but I think it's a GREAT language for writing games, and is going to take off at some point.

jlongster6• 12 years ago

Very cool! Hooking up the internal gambit REPL was finicky because it never got much love. I think Marc polished it up somewhere though. Still, a quick in-game REPL like that goes a long way.

The cool thing about having a real Gambit REPL was that you could use the Gambit debugger in real-time. So if an error ever occurred, the debugger REPL would pop up and you could step around. You also get all the builtin stuff for inspecting cooperative threads and such.

Anyway, it would be a great minimalistic environment if it was fleshed out more. Part of my mission in the JavaScript world is to bring these concepts to more people, and hopefully lead them to Clojure/Scheme/etc.

Did you use a module system? Last I remember Black Hole was getting really advanced. Did that ever take off within Gambit?

kennethtilton• 12 years ago

<g> Your exercise may be the take-off point.

You sound like you know how to code. Can you talk a little more about how the algorithm you were confronting made the effort of getting a Scheme platform working worthwhile? Understood if the answer is "not that big an effort". :)

Part of my question is that a solid lisp (of any ilk) programmer can program non-lispy languages in a lispy way.

billrobertson42• 12 years ago

I have been tempted to try your stuff many times. But ultimately no experience with Scheme or ios (and lets face it the time to motivation ratio wasn't good enough either).

It is great work, and I think there's value in making other languages that don't require huge runtimes viable for ios development.

Just today I found a Clojure/ObjC bridge: https://github.com/galdolber/clojure-objc

Vekz• 12 years ago

James those posts were disruptive and inspiring I know several people that were attracted to LISP and functional languages because of them (myself included). I think its a great strategy to intro and highlight these functional aspects in Javascript like what you're doing with sweet.js. It will bring more developers into the functional domain. Now we just need a scheme environment that is as robust as node.js and npm

matheusbn• 12 years ago

Well done! Gameplay video link: https://www.youtube.com/watch?v=1T11wl70wjc

mjt0229• 12 years ago

Nice work! I think I played ultimate with you this past summer, and we talked about this on the way to a game.

rrradical16• 12 years ago

Woah, small world! Not sure who this is though. Shoot me an e-mail? Contact info on website, asivitz.com

Kiro• 12 years ago

OT but what is ultimate?

mark212• 12 years ago

a frisbee based game:

http://en.wikipedia.org/wiki/Ultimate_(sport)

my college football team played it as a spring sport during "optional" workouts and it was brutal. Like rugby, only with a forward pass.

rrradical16• 12 years ago

A great sport: http://www.youtube.com/watch?v=uq3pg0JcJSI

keithflower2• 12 years ago

The Gambit interpreter (REPL) itself also runs on the iPhone

https://itunes.apple.com/us/app/gambit-repl/id434534076?mt=8

and on the Android platform (updating it with the latest version of Gambit is on my todo list):

http://apps.keithflower.org/?page_id=152

http://apps.keithflower.org/?p=223

https://play.google.com/store/apps/details?id=org.keithflowe...

Note that this is just the interpreter itself - not a very good way of writing games for Android.

weavie• 12 years ago

If you could update it so you could make the scripts edit fields full screen that would be awesome! it is really hard editing then in the tiny boxes they are at the minute.

keithflower2• 12 years ago

Thanks for the feedback. The intent in that version was to mimic Marc's (Gambit author Marc Feeley) past iOS version as closely as possible (via webview) - I'll see what he's doing with his latest iOS version and also try to include a full screen option.

xkarga00• 12 years ago

Just downloaded and tried the app. Simple and elegant, very good work!

tokipin• 12 years ago

I thought "non-Objective C" languages weren't allowed in the App store, or something like that.

sandyarmstrong• 12 years ago

That was never consistently enforced, and was eventually removed as a rule.

deadfall• 12 years ago

"Gambit compiles the Scheme code down to C, which I can then link to Objective-C for iOS, or port to Android or any other platform that Gambit supports."

loumf• 12 years ago

That was in the rules and quickly abandoned. What they care about is that you don't load new code from the Internet. Ostensibly, the reason is security, but the real reason is they don't want you to make an app store.

JavaScript in webviews is excepted because you couldn't show a website without that.

If you don't get new code from the Internet (for example, someone types it in) that's ok. It's even ok to copy and paste it from the Internet.

jcromartie• 12 years ago

This was assumed to be the case until approximately early 2010.

alvatar• 12 years ago

Great work! :) Congratulations! For those who want to try developing in Scheme, I'm working on a project that could help you get started. Currently only Android is available, but as soon as possible iOS will be as well. http://schemespheres.org

codegeek2• 12 years ago

Good stuff. Interestingly, the very first programming language offered in introductory CS class at my college was Scheme at the time (2000). The power of 'car' and 'cdr' still resonates in my head. At times, the parenthesis used to give me dyslexia but good old days of doing stuff like:

    (car(cdr(car(cdr(cdr a)))))

wonnage• 12 years ago

(cadaddr a) :P

codegeek2• 12 years ago

but that takes the fun out saying "car of the cudar of the cudar of...". Seriously though, such a simple concept of list manipulation can be used to solve so many problems. I never realized the power of this until a long time after.

brudgers• 12 years ago

The power of Lisp is that it has a word for this concept.

latj2• 12 years ago

Get a copy of this for the kids!

http://www.amazon.com/The-Little-Schemer-4th-Edition/dp/0262...

mentos• 12 years ago

One of the best CS classes I took in college was an introduction to scheme that used 'The Little Schemer' as its text book. Having only worked in imperative languages it really opened my head up!

klibertp2• 12 years ago

I just read the chapter about fixed point combinator (aka Y). It's great, not only for kids.

I tried reading the book a few years ago, I remember being irritated by the QA style it uses and dumping it because of it. On my second attempt I realized that it's only irritating if you know the answers very well and skipped to the chapter I didn't have so much confidence in understanding. And it was very pleasant experience, especially when I stopped to think a little before reading the answers. It felt like I was having fun.

So I'd advise to give a book a go, even if you are confident in your Scheme and FP skills. Just skip the parts which seem too obvious to you and get to the interesting stuff, you won't be disappointed.

Now it's time for The Seasoned Schemer, I guess :)

Shivetya• 12 years ago

After reading the story I just have to recall stories from the guys who flew and serviced F4s, they joked they could fly without either wing simply because it was just a rocket sled.

We had one guy knicknamed Major Cablecutter as he "clipped" the guidelines of a radio tower one time. He also had come back more than once with branches stuck to his F4. Being that they were only "Recon" they tended to be aggressive during war games and this game guy over stressed his airframe turning into some F18s trying to tag him.

So many military planes have such high thrust to weight ratios I do not doubt that wings merely become the means to stable flight

smoyer• 12 years ago

Your comment is great ... but it belongs with a different post.

Oculus• 12 years ago

I think you meant to comment on this post: https://news.ycombinator.com/item?id=7360011

dsjoerg• 12 years ago

Writing a whole iOS game in Scheme is about as crazy as flying an F4 with only one wing.

curiousphil• 12 years ago

This comment made me think this game must have some incredible unseen angle not shown in the screenshots on the App Store. Brilliant!

motxilo• 12 years ago

I wondered what Scheme dialect was F4. Epic!

nandemo• 12 years ago

Yeah, I thought "wow, you start flying a bunch of colored pixels, but eventually it turns into an F4!".

hardwaresofton• 12 years ago

This is either a simple mistake, or the greatest cross-thread advertisement I've ever read

ct1• 12 years ago

https://en.wikipedia.org/wiki/Cavalese_cable_car_disaster_(1...

Just the first that comes to mind.

oliverlord• 12 years ago

great work :) congrats

rrradical16• 12 years ago

thank you!

elwell• 12 years ago

It shows how spoiled I am that I expected a github link.

dogprez• 12 years ago

I play around with this a bit, a few things I learned is that XCode 5.0's llvm crashes when compiling Gambit-C 4.7.0's generated C code. The beta for 5.1 has a fix. Here are a few demos that might help a few people:

scheme REPL over TCP using chibi scheme: https://github.com/clarkeaa/Scheme_iOS_REPL

calling in and out of Gambit-C: https://github.com/clarkeaa/HelloGambit

You can grab a precompiled Gambit-C library from the later project if you want.

hoprocker• 12 years ago

It's truly inspiring to see a project like this completed. I've been wanting to combine mobile (specifically Android) and some sort of Lisp dialect for a while.

Am I interpreting correctly from some of the other components that doing the programming in a language-once-removed (ie Scheme instead of Obj-C) opens an easier path to compiling for both iOS and Android?

rrradical16• 12 years ago

That was part of my motivation for using Scheme, yes. Many indie developers are using the Unity engine which can compile to many different targets. (But that uses C# as far as I know.)

arms• 12 years ago

Very cool! I always like seeing when something is built using a typically non-traditional language for the environment. I downloaded the game to see how well it performed, and I gotta say, it's a lot of fun. Great job!

lumens2• 12 years ago

I love the originality on display with this game mechanic. Too many "samesies" games out there for my tastes.

This developer has another puzzler in the App Store as well: Button Brigade, also quite original, but more of an adventure style puzzle game.

https://itunes.apple.com/us/app/button-brigade/id542991688?m...

http://asivitz.com/button_brigade/index

minikomi• 12 years ago

Wow, I've been thinking about this a lot lately. I would pay for a good series of tutorials or an ebook on this topic maybe implementing something well known like Tetris etc.

Flow2• 12 years ago

Dear rrradical,

Tried your game, was not disappointed. :-) It's almost spooky that your post came at this time, for I have read a lot about Scheme->C systems this week. This PDF made a great impression on me of the gambit scheme system. http://www.iro.umontreal.ca/~gambit/Gambit-inside-out.pdf

I have a few questions for you:

1. I installed Gambit-Scheme via Brew and compiling any scheme file results in a clang segfault. How did you get around this? For now I use gcc instead. :-/

2. Why Gambit-Scheme and not Chicken-Scheme? I can't really decide which is the better choice for writing a game.

3. Do you use continuations to make coroutines in your game?

rrradical16• 12 years ago

1. I think the segfault is explored in this thread: http://article.gmane.org/gmane.lisp.scheme.gambit/7068/match...

Basically, the problem is with the version of llvm/clang that Apple uses in Xcode 5.

Some of the newer Xcode betas might fix it. I personally use the Xcode 4 compiler. You could probably also build your own clang from their SVN.

For more info you could probably ask the mailing list.

2. I definitely looked at chicken, and I can't remember my exact reason for going with gambit, but it was a practical one. I don't think I could get chicken up and running on the iphone for some reason. Chicken did seem to be better documented with better libraries. Gambit may be faster though.

(I started working on this about a year ago. The situation may be completely different now.)

My game isn't too complex, compared to, say, a first person shooter. I'm not sure if the GC implementation would start to matter in that circumstance. I recommend trying one and then if you're happy with it, great. If not, most of the code will be portable.

3. No. I don't have much experience with them (besides learning the basics in school). I did use a lot of closures, anonymous lambdas, and lambda builder functions.

Glad you're enjoying the game!

eddieroger• 12 years ago

Somewhere, deep in Lindley Hall at Indiana University, is an old professor exclaiming, "I told them people used it!"

I wonder if I'd have taken more to Scheme if I were learning it now. At the time, I was double majoring CS and Telecom, but the world of open source hadn't been as friendly to Mac as it is now, and Macs were a prereq for TCom. Getting Scheme running on my old iBook was a pain in the ass, let alone the assignments (which still didn't match the untouchable stability of our automated grading system). I conceptually understood why I needed to learn it, and even grasped many of the concepts of what I was learning, but it wasn't the language for me.

feeley• 12 years ago

I just downloaded the game. Very cool! I wish I has written it... oh wait... given that I wrote Gambit, in a sense I wrote most of the game! It gives me a warm fuzzy feeling!

Your in game REPL is neat. For developing games, where there's a need to explore variations quickly, it is a powerful tool. I'm currently working on a remote REPL for Gambit-JS, so that you can remotely debug Scheme code (possibly games) running in the browser.

Show HN: My current App Store Featured Game was written entirely in Scheme

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