The Rakudo implementation has a few modules included you may want to use; please note that the implementation is not part of the Raku specification and thus might be subject to change without prior notice. The following is a list of them, along with links to their source code.
CompUnit::* modules and roles
These modules are mostly used by distribution build tools, and are not intended to be used (at least until version 6.c) by the final user.
NativeCallNative Calling Interface (docs)
Pod::To::TextUsed by several external modules