Hare is a systems programming language.
For information about bootstrapping a working Hare toolchain from scratch, see Hare Installation on the website.
All contributors are required to "sign-off" their commits (using
git commit -s) to indicate that they have agreed to the Developer Certificate of
Origin, reproduced below.
Developer Certificate of Origin Version 1.1 Copyright (C) 2004, 2006 The Linux Foundation and its contributors. 1 Letterman Drive Suite D4700 San Francisco, CA, 94129 Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed. Developer's Certificate of Origin 1.1 By making a contribution to this project, I certify that: (a) The contribution was created in whole or in part by me and I have the right to submit it under the open source license indicated in the file; or (b) The contribution is based upon previous work that, to the best of my knowledge, is covered under an appropriate open source license and I have the right under that license to submit that work with modifications, whether created in whole or in part by me, under the same open source license (unless I am permitted to submit under a different license), as indicated in the file; or (c) The contribution was provided directly to me by some other person who certified (a), (b) or (c) and I have not modified it. (d) I understand and agree that this project and the contribution are public and that a record of the contribution (including all personal information I submit with it, including my sign-off) is maintained indefinitely and may be redistributed consistent with this project or the open source license(s) involved.
We are not your lawyer, but here is a simple explanation of the intention behind the Hare licenses.
The Hare standard library is available under the terms of the Mozilla Public License (MPL). You can freely link to the standard library with software distributed under any license, but if you modify the standard library, you must release your derivative works under the MPL as well.
The executables - the build driver, hare, and the compiler, harec, are available under the GPL 3.0 (but not any later version). This permits free use and redistribution, but any changes to it require you to share the derivative work under the terms of the GPL. It is stricter than the MPL; if you link to the compiler or build driver code from a third-party program it will require you to release the third-party code as well.
In short, you can write programs in Hare which use the standard library and distribute those programs under any terms you wish. However, if you modify Hare itself, you must share your changes as well.
The Hare specification is licensed much more strictly: CC-BY-ND. This license allows free redistribution of the document, but prohibits derivative works entirely. The purpose is to prevent the proliferation of vendor extensions to the language itself. However, these terms only apply to the specification itself: if you use the specification to write an implementation of the Hare language, you are not restricted in how you license your work.