Status of GHC runtime dependency on GNU multi precision arithmetic library

Brian Hulley brianh at
Thu Aug 16 17:55:25 EDT 2007

Duncan Coutts wrote:
> On Thu, 2007-08-16 at 14:22 +0100, Brian Hulley wrote:
>> .. For example, the LGPL requires you to give permission to people 
>> to reverse engineer your application... thus it may 
>> not even be possible for me to comply with the terms of the LGPL.
> >From the LGPL v3:
>         You may convey a Combined Work under terms of your choice that,
>         taken together, effectively do not restrict modification of the
>         portions of the Library contained in the Combined Work and
>         reverse engineering for debugging such modifications, if you
>         also do each of the following:
>         [list of stuff you have to do]
> So it looks like you only have not restrict reverse engineering for the
> purposes of making updated GMP libs work with your program. Since the MS
> Runtime components do not interact directly with the GMP at all you
> shouldn't need to grant users the right to reverse engineer those
> components. Indeed it's only ghc library and rts code that would
> interact with gmp.dll.

Thanks for suggesting that. It sounds reasonable though I tend to get a 
bit paranoid when it comes to legal things - will the FSF agree with the 
above interpretation etc.
> BTW, I don't think it should be too hard to construct a notice that
> indicates that portions of the work are covered by specific copyright
> licences, the details of which are available. After all Microsoft have
> dozens of these notices for various bits of BSD code they use and nobody
> mistakes Windows for Free software.

True, but if there's any chance of just getting rid of the GMP 
altogether from a version of GHC there would be no tricky issues when it 
comes to distributing proprietary apps, thus potentially increasing 
GHC's user base, making Haskell more popular, and hopefully leading to 
more BSD3 libs being written by those new users... ;-)

Best regards, Brian.

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