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This is Rakudo, a Raku Programming Language compiler for the MoarVM, JVM and Javascript virtual machines.

Rakudo is Copyright © 2008-2022, Yet Another Society. Rakudo is distributed under the terms of the Artistic License 2.0. For more details, see the full text of the license in the file LICENSE.

This directory contains only the Rakudo compiler itself; it does not contain any of the modules, documentation, or other items that would normally come with a full Raku distribution. If you're after more than just the bare compiler, please download the latest Rakudo Star package.

Rakudo is currently the most developed implementation of the Raku language; though there have been other partial implementations in the past. The Rakudo compiler has moar, jvm and js backends. Note that each backend has a slightly different set of features. For historical compilers see

Recent changes and feature additions are documented in the docs/ChangeLog text file.

Building and Installing Rakudo

Build Status

See the file for detailed prerequisites and build and installation instructions. Check for platform specific notes.

The general process for building is running perl with the desired configuration options (common options listed below), and then running make or make install. Optionally, you may run make spectest to test your build on Roast, the Official Raku test suite. To update the test suite, run make spectest_update.

Installation of Rakudo simply requires building and running make install. Note that this step is necessary for running Rakudo from outside the build directory. But don't worry, it installs locally by default, so you don't need any administrator privileges for carrying out this step.

Configuring Rakudo to run on MoarVM

To automatically download, build, and install a fresh MoarVM and NQP, run:

$ perl --gen-moar --gen-nqp --backends=moar

Please be aware, that this will install MoarVM and NQP into your given --prefix before exits.

Alternatively, feel free to git clone and manually and install them individually.

Configuration flags can be passed to MoarVM's using the --moar-option flag. For example, if you wish to use Clang when GCC is the default compiler selected for your OS, use the --compiler flag:

$ perl --gen-moar --moar-option='--compiler=clang' \
    --gen-nqp --backends=moar

If the compiler you want to use isn't known by MoarVM or you have multiple versions of the same compiler installed, the --cc flag can be used to pass its exact binary:

$ perl --gen-moar --moar-option='--cc=egcc' \
    --gen-nqp --backends=moar

Custom optimization and debugging levels may also be passed through:

$ perl --gen-moar --moar-option='--optimize=0 --debug=3' \
    --gen-nqp --backends=moar

For more information on how MoarVM can be configured, view MoarVM's

Configuring Rakudo to run on the JVM

Note that to run Rakudo on JVM, JDK 1.9 or higher must be installed. To automatically download, build, and install a fresh NQP, run:

$ perl --gen-nqp --backends=jvm

If you get a java.lang.OutOfMemoryError: Java heap space error building rakudo on the JVM, you may need to modify your NQP runner to limit memory use. e.g. edit the nqp-j / nqp-j.bat executable (found wherever you installed to, or in the install/bin directory) to include -Xms500m -Xmx3g as options passed to java. Alternatively, you can set JAVA_OPTS env var; e.g. export JAVA_OPTS="-Xmx51200000000"

Please be aware, that this will install NQP into your given --prefix before exits.

Alternatively, feel free to git clone manually and install it individually.

Multiple backends at the same time

By supplying combinations of backends to the --backends flag, you can get two or three backends built in the same prefix. The first backend you supply in the list is the one that gets the rakudo name as a symlink, and all backends are installed separately as rakudo-m or rakudo-j for Rakudo on MoarVM, or JVM respectively.

The format for the --backends flag is:

$ perl --backends=moar,jvm --gen-moar --relocatable
$ perl --backends=ALL --gen-moar --relocatable

ALL refers to moar, jvm and javascript backends.


Ensure the test suite is installed

The roast test suite is installed as the t/spec directory under your rakudo directory. If your installed rakudo source directory doesn't have t/spec installed, then you can clone it like this:

git clone t/spec

Note the rakudo code includes an entry in its .gitignore file so git will ignore any content under t/spec.

Now you can run tests in the rakudo directory.

Running tests

Run the full spectest:

$ make spectest   # <== takes a LONG time!!

To run a single test, one must use make because of the tooling required to run the spectests. For example:

$ make t/spec/S03-operators/comparison.t

Run all tests in one S* directory with a sh script. One example:

$ cat

# specify the desired directory:

# collect the individual files
F=$(ls $D/*t)

# and run them
for f in $F
    echo "Testing file '$f'"
    make $f
echo "All tests in dir '$D' have been run."

That can be written as a one-liner:

for f in $(ls t/spec/S26-documentation/*t); do make "$f"; done

Where to get help or answers to questions

There are several mailing lists, IRC channels, and wikis available with help for the Raku Programming Language and Rakudo. Figuring out the right one to use is often the biggest battle. Here are some rough guidelines:

The central hub for Raku information is This is always a good starting point.

If you have a question about Raku syntax or the right way to approach a problem using Raku, you probably want the “” mailing list or the IRC channel. The mailing list is primarily for the people who want to use Raku to write programs, so newbie questions are welcomed there. Newbie questions are also welcome on the #raku channel; the Rakudo development teams tend to hang out there and are generally glad to help. You can follow @raku_news and on Twitter, there's a Raku news aggregator at Planet Raku.

Questions about NQP can also be posted to the #raku IRC channel. For questions about MoarVM, you can join #moarvm on Libera.

Code of Conduct

The Raku community is committed to providing a welcoming, inclusive, safe, and enjoyable environment for everyone. Programming should be -Ofun. The Raku Community therefore has adopted a Code of Conduct. Please see the CoC Incident Report Guide should you feel the need to report any violations of the Code of Conduct.

Reporting bugs


Submitting patches

If you have a patch that fixes a bug or adds a new feature, please create a pull request using github's pull request infrastructure.

See our contribution guidelines for more information.

Line editing and tab completion

If you would like simple history and tab completion in the rakudo executable, you need to install the Linenoise module. The recommended way to install Linenoise is via zef:

$ zef install Linenoise

An alternative is to use a third-party program such as rlwrap. Documentation on rlwrap can be found here.


See CREDITS for the many people that have contributed to the development of the Rakudo compiler, some of which have left this existence way too early.