Cabal && license combinations

Duncan Coutts duncan.coutts at
Thu Feb 10 11:59:53 CET 2011

On Wed, 2011-02-09 at 03:47 +1300, Vivian McPhail wrote:

> > license: Foo, Bar
> >
> Could this be computed automatically from the source files by Cabal?

I would not want to rely on that.

> Looking specifically at hmatrix, there are three kinds of modules
>    i) bindings to GSL            GPL
>    ii) bindings to LAPACK     BSD
>    iii) pure Haskell                hmatrix author's choice
> 1) Am I correct in thinking that even the bindings modules (the
> Haskell parts, not the C files) can be under any licence, FOO, chosen
> by the author, but the binary _linked_ to, say, GSL has to comply with
> FOO and GPL?

Yes. Code you write can be under any license you like. When someone uses
the combination then they have to comply with all the licenses (so
implicitly there's the constraint that the license you pick must be
compatible with the license of the other parts).

> 2) If someone uses hmatrix but no GSL functions (hence there are no
> GSL functions in the linked binary) can they get away with not
> complying with the GSL requirement?

Not sure. In practice I don't think you can achieve that with our


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