Cabal && license combinations
Dear All, There was recently a discussion on haskell-cafe ( http://www.mail-archive.com/haskell-cafe@haskell.org/msg86472.html) about licenses of libraries such as hmatrix and the combination of various different licences. One question was about per-package versus by-file licenses: In Haskell the compilation unit is the module, and the per-file cabal header allows for a license field. It seems then that a package should be the least restrictive combination of all the licenses in all the contained modules. If this has to become a hand-coded fancy function of various GPLx, BSDy, OpenSource, and other licenses then so be it. That is the legal reality. And use of a BSD3 module in hmatrix that does not depend upon GPL'd GSL modules would be acceptable. In short, I argue for a per-file(module) license regime. Vivian
It seems then that a package should be the least restrictive combination of all the licenses in all the contained modules.
Omit the words "least restrictive" and I think you are correct. To combine licences, just aggregate them. There is no lattice of subsumption; no "more" or "less" restrictive ordering. It's simple: you must obey all of them. Some aggregations introduce a contradiction of terms, so you cannot legally aggregate those modules without breaking some term. But if the terms of the aggregated licences are compatible rather than contradictory, then all is good. Regards, Malcolm
On Mon, 2011-02-07 at 14:42 +0000, Malcolm Wallace wrote:
It seems then that a package should be the least restrictive combination of all the licenses in all the contained modules.
Omit the words "least restrictive" and I think you are correct.
To combine licences, just aggregate them. There is no lattice of subsumption; no "more" or "less" restrictive ordering. It's simple: you must obey all of them. Some aggregations introduce a contradiction of terms, so you cannot legally aggregate those modules without breaking some term. But if the terms of the aggregated licences are compatible rather than contradictory, then all is good.
Right, so the effect of per-file/mixed licenses could be achieved by letting packages specify a list of licenses: license: Foo, Bar Meaning you may copy/distribute provided you comply with all these licenses. Note that this does not cover dual licensing, e.g. Foo or Bar at distributor's choice. Duncan
participants (3)
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Duncan Coutts -
Malcolm Wallace -
Vivian McPhail