The Packrat parser combinator library is licensed under the Sunset License v1.0.
The full text of this license is as follows:
SUNSET LICENSE Version 1.0, June 2017 1. You may copy, modify, use, sell, or distribute this work, verbatim or modified, for any purpose. 2. If you sell or distribute this work, whether verbatim or modified, you must include a copy of this license, and you must make the source code available for no extra charge. 3. A modified version of this work must be clearly labeled as such. 4. Derivative works must also be licensed under this license or a license of equivalent terms. As an exception, linking this work with another, whether statically or dynamically, does not impose any license requirements on the other work. 5. If a minimum of 15 years have passed since the date of first publishing for a part of this work, then that part is placed into the public domain and you may do whatever you want with it, regardless of all other clauses.
This text can also be found in license.txt in the main directory of this repo.