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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 a modern support for concurrency and multi-core CPU.

The language is in its early bootstrap phase, once fully done, it will be self-hosted. The Red software stack contains also another language, Red/System, which is a low-level DSL. It is a limited C-level language with a REBOL look'n feel, required to build Red's runtime library and be the target language of Red's compiler. More information at

Running the Red hello script

The compiler and linker are currently written in REBOL and can produce Windows, Linux, Syllable, Android and Mac OS X executables. So, for now, a REBOL/Core binary is required to compile Red and Red/System programs. Please follow the instructions for installing the compiler tool-chain:

  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 click on the rebol.exe file to run it.

  5. From the REBOL console type:

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

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

    do/args %red.r "-v 1 %red/tests/"

Command-line options:

-d          : switches into debug mode.

-o <file>   : outputs executable to given path and/or filename.

-t <target> : cross-compiles to another target (see table below).

-v <level>  : sets verbose mode. 1-3 are for Red only, above for Red/System.

Important: Red will be distributed as a binary to end users and the effect of:


will be to compile and run it from memory directly. So the -o option will become mandatory in the future for generating an executable without running it. During the bootstrap stage, it is complex to support that feature, but anyway, we will implement it as soon as possible.

Running the Red/System hello script

  1. From the REBOL console type:

    change-dir %red-system/

  2. Type: do/args %rsc.r "%tests/hello.reds", the compilation process should finish with a ...output file size message.

  3. The resulting binary is in red-system/builds/, go try it! Windows users need to open a DOS console and run hello.exe from there.

The %rsc.r script is only a wrapper script around the compiler, for testing purpose. It accepts a -v <integer!> option for verbose logs. Try it with:

>> do/args %rsc.r "-v 5 %tests/hello.reds"

Cross-compilation support

Cross-compilation is easily achieved by using a -t command line option followed by a target ID. This command-line option works for both Red and Red/System compilers.

Currently supported targets are:

Target ID Description
MSDOS Windows, x86, console-only applications
Windows Windows, x86, native applications
Linux GNU/Linux, x86
Linux-ARM GNU/Linux, ARMv5
Darwin Mac OS X Intel, console-only applications
Syllable Syllable OS, x86
Android Android, ARMv5

For example, from Windows, to emit Linux executables:

>> do/args %rsc.r "-t Linux %tests/hello.reds"

From Linux, to emit Windows console executables:

>> do/args %rsc.r "-t MSDOS %tests/hello.reds"

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, just ignore those alerts and if possible, remove the Red folder path from the anti-virus scanner. We will try to workaround that in future releases. The badly reacting anti-virus apps are: Avira, AntiVir, BitDefender, F-Secure, F-Prot, DrWeb, Commtouch, Panda.


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.

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