October 28, 2012

Red alpha release

We have all waited long for this to happen, but it is finally there: first Red alpha release!

This is the biggest milestone since the initial release of Red System, as it marks the entrance of the higher layer of the Red software stack. There's still another layer pending, the JIT compiler, but that's for 2013, when Red will be self-hosted.

What Red can do so far?

So what happened since the first Red compiler release a little more than a month ago? We have added quite a lot of features actually:

  • 15 datatypes: block!, string!, char!, integer!, logic!, none!, word!, lit-word!, get-word!, set-word!, refinement!, action!, native!, op!, unset!.
  • 19 actions: make, form, mold, add, divide, multiply, subtract, append, at, back, clear, head, index?, length?, next, pick, poke, skip, tail.
  • 21 natives: if, unless, either, any, all, while, until, loop, repeat, foreach, forall, print, prin, equal?, not-equal?, strict-equal?, lesser?, greater?, lesser-or-equal?, greater-or-equal?, not.
  • 10 infix operators: +, - , *, /, =, ==, <, >, <=, >=.

String! datatype fully supports Unicode from end to end and in a cross-platform way, according to our plan (see the hello.red demo script).

We also have some unit tests (223 tests right now), but that number should rapidly increase once we will be able to fully port QuickTest framework to Red (in a couple of weeks, once Red will gain functions).

All those features were mostly coded in the last month, some parts are still lacking (e.g. refinements support for actions/natives) but that gives you an idea of the pace at which Red will be further developed.

However, we haven't started yet writting the documentation for Red language, we should decide soon on the kind of documentation we want (hint: you can make propositions about that on the Red mailing-list or FB page). Red API documentation will most probably be generated automatically from source code by extracting doc-strings.

What's not yet there?

A lot of things, but they will be added progressively until the end of the year, where we should have a pretty complete Red (bootstrap) implementation. So, the main pieces to implement are:

  • Red runtime lexer (LOAD native)
  • Functions and objects support
  • I/O support (including networking)
  • More complete memory allocator and a garbage collector.
  • Concurrency support
  • Additional datatypes

Can I try it already?

Red codebase is available at github, just clone it locally or download a packaged version. Some simple instructions to setup and run it can be found here. As we are still at the bootstrap stage, the installation process and usage is more complex than it should be, once self-hosted. Anyway, we should be able to deliver some test binaries soon and simplify the usage for those who want to play with the alpha releases.

How does Red work?

Currently Red scripts are statically compiled using the %red.r front-end wrapper. The Red lexer loads the UTF-8 encoded Red scripts in memory in form of blocks of values. Those blocks are then compiled to a Red/System script, that gets itself compiled to native code and outputs an executable binary. The Red/System compiler has been enhanced to be able to compile source code directly from memory.

Some compilation options are already available, the famous -t option from Red System is also present, allowing Red to cross-compile any script as easily as with Red/System.

This is just the beginning, so for now, whole Red runtime library is compiled with user scripts each time. We will add modular compilation support at some point to get the full compilation speed back.

You can test the few example Red scripts from the repository. Here is what the demo.red script outputs on some of the platforms Red can already run on:

The missing characters in some of the screenshots are Chinese ones as I only have font support for them on Ubuntu.

Red was originally conceived to be statically typed. However, during the early stages of Red implementation, it appeared that an hybrid typing system will be more adequate for a language that will support high-level scripting, without the burden of a sophisticated, but slow, type inference engine. The overhead of such inference engine can be very high (cf Scala slow compilation speed ). The hybrid type system works very simply, typing is optional, but if local variables and function returned values are typed by user, the compiler will be able to generate faster code (more than an order of magnitude faster for, e.g., pure math expressions) and catch more programming errors at compile time.

Red compiler does not do any optimization so far, it basically outputs the equivalent of an unrolled interpreter loop. Some optimizations will be added along the development of the bootstrap version of Red,  but the full extent of possible optimizations will be left for the self-hosted Red.  Firstly because the current compiler code is disposable, so we don't want to invest too much time in it, secondly because the final JIT compiler will allow even deeper optimizations thanks to reflection and profiling information collected at runtime.

Red/System changes

Red/System has been improved significantly during the Red early development:
  • function pointer support has been extended and improved, dereferencing is now possible.
  • 20 issues have been fixed.
  • some long-standing bugs with GTK+ and other bindings on ARM platforms have been fixed.

So, what's coming next?

Red will now mature very quickly, as functions and objects will make their entrance in the next days/weeks. A new Red alpha release is planned very soon, probably for mid-november with a lot of new features.

The work on shared library generation for MacOS and Linux platforms is on-going. Once available, we'll be able to literally "plug" Red in a lot of third-party apps, including other programming languages. Also, this will enable (or make easier) the bridging with some external systems like Java, .Net and objective-c, in order to fully support the main mobile platforms.

As you can see, next months will see some important parts of Red come to life, be sure not to miss them, follow us on our mailing-list, on Twitter, IRC and Facebook.

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