Would MPL be the right license?

[diri...@gmail.com]

I am working with a group that is currently in the process of creating a piece of software that will be building a programming language, and hence contain a compiler and something for reading the compiled code, as well as a specification for the code the compiler produces and takes in.

Would it be right to license this under the MPL (2.0) if we wanted the following things:
The work to be possible to use with proprietary software.

Developers who wished to use our code to still have to release our code under an open source license, while being able to keep their own code proprietary. (Using our code as a library or part of their code and only releasing the source code for our files)

Compatibility with Apache, BSD, and GPL licenses.

[Gervase Markham]

Hi Dirius,

You are better consulting your own lawyers about this, but here are some
thoughts:

On 12/02/15 02:54, diri...@gmail.com wrote:
> I am working with a group that is currently in the process of
> creating a piece of software that will be building a programming
> language, and hence contain a compiler and something for reading the
> compiled code, as well as a specification for the code the compiler
> produces and takes in.
>
> Would it be right to license this under the MPL (2.0) if we wanted
> the following things: The work to be possible to use with proprietary
> software.

That would generally be fine, although it would depend if your system
involves the compiler copying parts of itself into the compiled code. If
it did, you would need to license those parts under some more liberal
license to avoid the proprietary code being affected by the MPL. Whether
this is true or not depends on how your compiler works.

> Developers who wished to use our code to still have to release our
> code under an open source license, while being able to keep their own
> code proprietary. (Using our code as a library or part of their code
> and only releasing the source code for our files)

That would also be generally true, although the MPL is only a file-level
copyleft and so it is possible to work around its copyleft provisions,
given sufficient incentive and willingness to rearrange one's source
tree and code organization for licensing purposes.

> Compatibility with Apache, BSD, and GPL licenses.

It depends what you mean by "compatibility". The compatibility chart for
the four licenses you mention is:

BSD -> Apache -> MPL 2 -> GPL

Where "A -> B" means "code under license A can be copied into files
under license B". The reverse is not true. You can't copy MPLed code
into a BSD-licensed file without the file becoming MPLed.

Gerv