Red Programming Language
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Red Programming Language

Red is a new programming language strongly inspired by Rebol, but with a broader field of usage thanks to its native-code compiler, from system programming to high-level scripting, while providing modern support for concurrency and multi-core CPUs.

Red has its own complete cross-platform toolchain, featuring two compilers, an interpreter and a linker, not depending on any third-party library, except for a Rebol2 interpreter, required during the bootstrap phase. Once complete, Red will be self-hosted.

The Red software stack also contains another language, Red/System, which is a low-level dialect of Red. It is a limited C-level language with a Red look'n feel, required to build Red's runtime library and be the target language of Red's compiler. More information at

Making a Red "Hello World"

The Red toolchain comes as a single half-megabyte executable file that you can download from here for the big-3 platforms.

  1. Put the downloaded red binary in a folder that's in the PATH, or just in the working folder.

  2. In a code or text editor, write the following Hello World program:

     Red [
     	Title: "Simple hello world script"
     print "Hello World!"
  3. Save it under the name:

  4. From a terminal (works from DOS too), run it with:

     $ red
  5. You should see the Hello World! output.

  6. Want to generate a compiled executable from that program?

     $ red -c
     $ ./hello
  7. Want to cross-compile to another supported platform?

     $ red -t Windows
     $ red -t Darwin
     $ red -t Linux-ARM

The command-line options are:

red [options] [file]


Any Red or Red/System source file. If no file and no option is provided, the REPL will be launched. If a file with no option is provided, the file will be simply run by the interpreter (it is expected to be a Red script with no Red/System code).


-c, --compile                  : Forces generation of an executable in 
                                 the working folder.

-d, --debug, --debug-stabs     : Compile source file in debug mode. STABS
                                 is supported for Linux targets.

-dlib, --dynamic-lib           : Generate a shared library from the source

-h, --help                     : Output this help text.

-o <file>, --output <file>     : Specify a non-default [path/][name] for
                                 the generated binary file.

-r, --no-runtime               : Do not include runtime during Red/System
                                 source compilation.

-t <ID>, --target <ID>         : Cross-compile to a different platform
                                 target than the current one (see targets
                                 table below).

-v <level>, --verbose <level>  : Set compilation verbosity level, 1-3 for
                                 Red, 4-11 for Red/System.

-V, --version                  : Output binary version string.

--red-only                     : Stop just after Red-level compilation. 
                                 Use higher verbose level to see compiler
                                 output. (internal debugging purpose)

Cross-compilation targets:

MSDOS        : Windows, x86, console (+ GUI) applications
Windows      : Windows, x86, GUI applications
Linux        : GNU/Linux, x86
Linux-ARM    : GNU/Linux, ARMv5
Darwin       : MacOSX Intel, console-only applications
Syllable     : Syllable OS, x86
FreeBSD		 : FreeBSD, x86
Android      : Android, ARMv5
Android-x86	 : Android, x86

Running the Red REPL

  1. Just run the red binary with no option to access the REPL.

     -=== Red Console alpha version ===-
     (only ASCII input supported)
  2. You can use it to test rapidly some Red code:

     red>> 1 + 2
     == 3
     red>> inc: func [n][n + 1]
     == func [n][n + 1]
     red>> inc 123
     == 124

Running Red from the sources

The compiler and linker are currently written in Rebol. Please follow the instructions for installing the compiler toolchain in order to run it from sources:

  1. Clone this git repository or download an archive (ZIP button above or from tagged packages).

  2. Download a Rebol interpreter suitable for your OS: Windows, Linux, Mac OS X, FreeBSD, OpenBSD, Solaris

  3. Extract the rebol binary, put it in root folder, that's all!

  4. Let's test it: run ./rebol, you'll see a >> prompt appear. Windows users need to double-click on the rebol.exe file to run it.

  5. From the REBOL console type:

     >> do/args %red.r "%tests/"

The compilation process should finish with a ...output file size message. The resulting binary is in the working folder. Windows users need to open a DOS console and run hello.exe from there.

To see the intermediary Red/System code generated by the compiler, use:

    >> do/args %red.r "-v 2 %tests/"

Anti-virus false positive

Some anti-virus programs are a bit too sensitive and can wrongly report an alert on some binaries generated by Red, if that happens to you, please fill a ticket here, so we can report the false positive.


Both Red and Red/System are published under BSD license, runtime is under BSL license. BSL is a bit more permissive license than BSD, more suitable for the runtime parts. alpha