The not so great automatic Haskell licensor
Licensor is a program that generates a report of the dependencies and transitive dependencies of a Haskell project and their licenses.
Choosing a license for a software project or determining whether a particular dependency can be added to a project can be projects themselves. Unless starting from scratch, programmers should consider the licenses of the dependencies and transitive dependencies of their projects to make informed decisions and avoid license compatibility issues.
Of course, this is just a starting point. “Beyond (…) general observations, it is difficult, if not impossible, to provide precise guidance about what licenses may or may not be compatible with each other. (…) Programmers who are considering combining code governed by two or more different licenses should proceed cautiously” (Andrew M. St. Laurent).
Licensor is not a lawyer and does not provide legal advice.
For more information about licenses and license compatibility issues, read the text of the licenses or consult with a lawyer before making any decision.
Licensor is not the only license compatibility helper for Haskell:
- Licensor uses a Cabal library and Stack program approach for detecting licenses and listing dependencies, respectively. For a Cabal library and program approach, consider using the cabal-dependency-licenses program.
Installation and usage
To install Licensor, use Cabal:
$ cabal update && cabal install licensor
Then, run the
licensor executable inside a Haskell project:
To see the license report for Licensor, clone the repository:
$ git clone https://github.com/jpvillaisaza/licensor
licensor inside the project:
$ cd licensor/ && licensor
Or build and run
licensor inside the project:
$ cd licensor/ && stack build --exec licensor
For more information, run
licensor 0.2.0 licensor [OPTIONS] Common flags: -? --help Display help message -V --version Print version information --numeric-version Print just the version number
Licensor uses the Stack program to list dependencies for a Haskell project. A future enhancement could be to use the Stack library.
Licenses and license detection
Licensor uses the Cabal library to detect the license of a Haskell project and its dependencies (including transitive dependencies). To do so, it uses the license field in the package description. A future enhancement could be to use both the license and licence file fields in the package description.
Cabal provides an enumeration of common open source and free software licenses. These are the licenses that appear in the reports generated by Licensor:
|GPL||GNU General Public License|
|AGPL||GNU Affero General Public License|
|LGPL||GNU Lesser General Public License|
|BSD2||BSD 2-Clause License|
|BSD3||BSD 3-Clause License|
|BSD4||BSD 4-Clause License|
|MPL||Mozilla Public License|
|AllRightsReserved||All rights reserved|
|UnspecifiedLicense||Unspecified license (All rights reserved)|
Feel free to create issues for reporting bugs and suggesting enhancements, or to fork the repository and open a pull request.
Licensor is licensed under the MIT License. See LICENSE.md.
Licensor (0.2.2) depends on the following libraries:
And the following licenses (including transitive dependencies):
|License||Number of libraries|
(Tested with Licensor 0.2.2, Stack 1.6.3, and Stackage Nightly 2018-01-16.)
- Allow http-conduit 2.3 (558fe3d)
- Allow base 4.10 and Cabal 2.0 (7bbb360)
- Allow use in multi-package project (f545a4c)
- Handle exceptions (ec640bb)
- Replace HTTP with http-conduit (f6735cb)
- Add command line arguments (2558a05)
- Add a library (835ac70)