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The reference command line interpreter for the Roo programming language

The Roo programming language

Roo is a cross-platform dynamically-typed interpreted open source scripting language which takes inspiration from Ruby (everything is an object) and Python (indentation is important). It supports both object-oriented and functional programming approaches. The reference interpreter is roo which is written in Xojo.

Full documentation is available in this repo.


To play with Roo you'll need to install the roo interpreter. This is a command line tool that runs your source code. It can also be used as a REPL (much like Ruby's irb command). To install, you have a few choices:

1. Use a package manager (easiest)

Simple installation with Homebrew and Scoop is offered for macOS and Windows users.

If you're using macOS you can use the excellent Homebrew package manager to quickly install Roo:

brew tap gkjpettet/homebrew-roo
brew install roo

You can make sure that you've always got the latest version of Roo by running brew update in the Terminal. You'll know there's an update available if you see the following:

==> Updated Formulae
gkjpettet/roo/roo ✔

Then you'll know there's a new version available. To install it simply type brew upgrade in the Terminal.

If you're using Windows I recommend using Scoop to install Roo. Once You've setup Scoop, simply type the following into the Command Prompt or the Powershell:

scoop bucket add roo
scoop install roo

To update Roo run the following commands:

scoop update
scoop update roo

2. Install the precompiled binary and its dependencies

If you can't/don't want to use a package manager then I provide precompiled binaries for macOS (64-bit), Windows (32/64-bit) and x86 Linux (64-bit). Essentially just make sure that you install the roo binary and all its dependencies (included in the download) within your system's $PATH. The Mac and Linux versions contain one file and one folder:

[roo Libs]

The Windows version includes several files and a folder:

[roo Libs]

I use a Mac and if I wasn't using Homebrew I would place roo and roo Libs/ in /usr/local/bin. You can grab the required files from the releases page.

3. Build the intepreter from source

Note: Requires a Xojo license

  1. Clone the repo (or download it as a ZIP file)
  2. Launch the src/cli/roo.xojo_project file in Xojo
  3. Resolve any missing Roo class dependencies

Number 3 above might require a little clarification. Xojo provides a mechanism for making classes and modules external to a project. This means that you can make changes to those classes and have them reflected in all of your projects which use them. Since I maintain the Roo IDE as well I keep the actual classes in a subfolder of this repo and reference them from this project. You can find them in the src/core/Roo. If the Xojo IDE asks you for the location of the various Roo classes, simply navigate to them and select them. You only need to do this once.

Comment out the contents of the PostBuildMac, PostBuildWin and PostBuildLinux IDE scripts in the Build Settings section of Xojo's navigator. These are only there to help me when I build releases to publish on GitHub. They are not needed for you to build the app and will only generate an error for you.

After you've built the app, remember to place the roo executable in your $PATH (and make sure the dependency folder/files are in the same place). The interpreter is written entirely in native Xojo code and no external plugins are required.

Once the roo interpreter is installed, you can start a REPL session by typing roo in the Terminal. This will give you a prompt and allow you to enter Roo code line by line and have it interpreted as you enter it. Good for playing around. It's worth noting that you don't have to terminate statements with semicolons a REPL session. To run a script, simply type roo [script.roo] where script.roo is the full path to the script to run.

Whilst there is no interactive debugger for Roo (yet), roo does provide reasonably accurate and helpful error messages if a problem is encountered either during program lexing, parsing or execution.

To quit a REPL session type CTRL-C or CTRL-D or CTRL-X (depending on your operating system). Or you can simply use the global quit statement.

4. Load the binary project

To simplify getting started with the project, I have also included the project saved in Xojo's binary file format. This can be found in /binary project/roo-cli.xojo_binary_project. Simply launch this is Xojo 2019 Release 1.1 or later and you're good to go.


You'll notices that this repo has an extras/ folder which contains goodies additional to the source code. These are detailed below:


Contains a custom syntax definition for the Roo programming language to allow you to highlight Roo code on webpages using Craig Campbell's Rainbow javascript syntax highlighter. I also include SASS and CSS files to colour the code.

Sublime Text 3

Contains a syntax definition file to enable Roo syntax highlighting in Sublime Text 3. It also contains light and dark colour themes.


The reference command line interpreter for the Roo programming language



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