framework for writing bundlers

 Librarian is a framework for writing bundlers, which are tools that resolve,
 fetch, install, and isolate a project's dependencies, in Ruby.
 .
 A bundler written with Librarian will expect you to provide a specfile listing
 your project's declared dependencies, including any version constraints and
 including the upstream sources for finding them. Librarian can resolve the
 spec, write a lockfile listing the full resolution, fetch the resolved
 dependencies, install them, and isolate them in your project.
 .
 A bundler written with Librarian will be similar in kind to Bundler, the
 bundler for Ruby gems that many modern Rails applications use.