[erlang-questions] A PropEr announcement

Richard Carlsson <>
Tue Jun 14 14:25:52 CEST 2011


On 06/14/2011 02:02 PM, Ulf Wiger wrote:
> On 14 Jun 2011, at 01:09, Vik Olliver wrote:
>> On 14/06/11 11:01, Francis Joanis wrote:
>>> I have a question about the GPL licensing of the tool itself:
>>> since it is GPL, doesn't it require to make the written tests
>>> themselves and to some extent the application under test GPL as
>>> well?
>>
>> Only if you distribute the tests. If you keep them to yourself,
>> you don't owe anyone anything. The GPL respects privacy.
>
> This could become an obstacle to adoption similar to what's been seen
> with Quviq QuickCheck: people who have Open Source projects need to
> publish (=distribute) test suites as well. Just as it's not very
> helpful to distribute test suites that require an expensive tool,
> people might be reluctant to publish PropEr-based tests if it
> requires them to convert to GPL.
>
> Kostis did say that they would make an exception for OSS projects. I
> could not find any such exception when quickly scanning the repos.
>
> BR, Ulf W

As I have remarked before on this list, I believe the normal GPL (all 
versions) cannot be used for Erlang modules, because the dynamic loading 
and linking of classes/modules at runtime is not considered to be any 
different from static linking - at least according to the FSF.

The standard Erlang library modules and the runtime system BIFs are 
published under the Erlang Public License, which is an even more 
restrictive variant of MPL. The MPL is not compatible with GPL 
(http://en.wikipedia.org/wiki/Mozilla_Public_License#Compatibility_with_GPL), 
due to some of its restrictions, so it should follow that the EPL is 
also not compatible.

If you want to enforce copyleft in your code, but not force it on other 
libraries that link with your code, you can use LGPL instead of GPL. 
(Preferably, use v3, which is compatible with Apache License 2.)

http://www.gnu.org/licenses/lgpl-java.html

     /Richard (not a lawyer)



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