Silver is an extensible attribute grammar system that support many modern extensions to Knuth's original design. These include higher-order attributes, reference attributes, forwarding, aspects, and collections attributes. Its type system support parametric polymorphism. Silver is distributed with Copper, a parser and context-aware scanner generator.

It is designed for the modular development of composable language extensions, with language features and analyses to support this.

Silver requires Java 8, Ant 1.10.0, Bash, and wget. It can run on Linux, MacOS, and Windows Subsystem for Linux (WSL) in Windows 10.

See The Silver Install Guide for detailed information on how to get Silver set up.

Silver is written in Silver, which means after cloning the GitHub repository you still need the executable Java jar files. You can download these by running the update script in this repository. This will do a git pull to update, then download jars, and clear any files generated by older versions of Silver. A one-stop-shop for updating after the initial clone.

Silver is currently developed and maintained by

• Lucas Kramer (krame505@umn.edu)
• Eric Van Wyk (evw@cs.umn.edu)

Past contributors include Ted Kaminski (tedinski@cs.umn.edu), Derek Bodin, Lijesh Krishnan, and Jimin Gao.

It is developed by the Minnesota Extensible Language Tools (MELT) Group (http://melt.cs.umn.edu) at the Department of Computer Science and Engineering (https://cs.umn.edu) at the University of Minnesota (https://umn.edu).

Software downloads, documentation, and related papers are available on the Melt group web site at http://melt.cs.umn.edu/.

Information about Copper and sample language frameworks developed with Silver can be found on the MELT Group web site at http://melt.cs.umn.edu

Actively-developed versions of this software are available on GitHub at https://github.com/melt-umn/silver.

Archival versions of this software are permanently available on the Data Repository of the University of Minnesota at https://doi.org/10.13020/D6QX07.

Other software and artifacts are also archived there and can be reached from this persistent link: http://hdl.handle.net/11299/206558.

We are very grateful to the National Science Foundation, the McKnight Foundation, DARPA, the University of Minnesota, and IBM for funding different aspects of our research and the development of Silver and Copper.

Silver and Copper are distributed under the GNU Lesser General Public License. See the files COPYING and COPYING.LESSER for details of these licenses. More information can be found at http://www.gnu.org/licenses/.