Sunday, April 15, 2012

Every few years I find a new language/platform for my experiments. I’d like to share them on the web, so I (mostly) limit myself to things that run in the browser. In the 1990s I used Java. In 2004, I started looking at Flash, but continued using Java. With help from Troy Gilbert, I switched to Flash in 2006, using the Motion-Twin Flash compiler (mtasc) instead of Adobe’s compiler. I continued using Flash, switching to Actionscript 3 and Adobe’s Flex compiler, to make Flash 9 and 10 applets. I also used Javascript for some projects. In an alternate history, Actionscript 3 was a possible future of Javascript/ECMAscript but that history didn’t come to pass. It’s a decent language, with things I miss from Javascript: static types, classes, packages, imports, etc. However, it’s time for a change of language.

I’ve switched from Actionscript to Haxe, Motion-Twin’s successor to mtasc. I’ve been watching Haxe over the years but was waiting for the right time. Unlike their mtasc compiler which can be used with the same source code as Adobe’s compiler, Haxe is a new language. It compiles to Javascript, Flash, Java, PHP, or C++, so it can be used for HTML5, Flash, iOS, Android, and webOS clients, as well as C++, Java, Node.JS, or PHP servers. I’m starting to work on new projects that are likely to involve: (1) HTML5 visualizations and games, (2) simple Flash games, and (3) C++ server code, so this seems like a good time to try Haxe. There are also libraries like NME that let me compile Haxe games to Windows, Mac, Linux, HTML5, Flash, iOS, Android, Blackberry, and webOS, if I want to go beyond web projects.

The language itself is nice. In addition to the things I’d expect (closures, packages, imports, classes, etc.), it contains things I’ve missed from my SML/OCaml days: typed unions, type inference, generics, and structural subtyping. It also has other nice features: external mixins, metadata, properties, explicit inlining, and macros. Everything’s an expression; there aren’t any statements. They understand the basics of covariance and contravariance. The compiler is written in OCaml. For a recovered programming language geek like me, there’s a lot going for it. It’s no Haskell or Scala but it’s a big step up from Actionscript. It’s also very … pleasant. I’m not sure how else to describe it.

I’ve not been using Haxe long, but have already had good luck with the multiplatform part, at least for Flash and Javascript. I had an algorithm for a Flash game, and I compiled it into Javascript and used it without any trouble. Since Actionscript, Javascript, and Haxe are all related, it works well. I’m less sure about how well it will work with C++, especially when it comes to garbage collection. There are probably lots of gotchas there. I also haven’t yet figured out how to use Javascript libraries from Haxe code; for my project I went the other way, using my Haxe library from Javascript code I wrote. I’ll learn more as I go.

I think the weakest part of Haxe is the ecosystem. The developers I have talked to so far are great; the language seems to attract good people. There’s a conference, a forum, and an IRC channel. However, the community is smaller than for Actionscript or Javascript: fewer people, fewer books, fewer web sites, fewer tutorials, fewer examples, fewer libraries. A few years ago when I chose Actionscript over Haxe, it was because I thought people would be using snippets of my code in their projects, I wanted to pick a language that lots of people used. That doesn’t seem to be helping me much. Instead, people read the code and learn from it, but write their own code, or they want to use my library as-is. So the number of people using the language is less important to me now. Supporting multiple platforms is becoming more important. With the map generation project, it was frustrating to have written everything for the client (Flash) and then later needing to run it on the server (C++). As HTML5 improves, I’m targeting more HTML5 and less Flash. Both of these tell me that cross-platform is becoming more important for my projects.

My current plan is to use Haxe for code I want to run across platforms, and use Javascript, Python, and C++ for code that is platform specific.

Update: [2013-Apr] Although I still use some Haxe, I'm not using it for cross-language coding much. For my web tutorials, I write in Javascript directly, except for core data structures and algorithms which I write in Haxe or Typescript, to get classes and type checking. For Flash projects, I use Haxe as a nicer Actionscript but I don't use the cross-language features, nor do I use NME for compiling to mobile. By the time I'm ready to write a game, the landscape (Typescript, Emscripten, Asm.js, ASC 2.0) may have changed enough that I'll re-evaluate then.

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