Duncan Coutts wrote:
On Thu, 2007-07-26 at 08:53 +0100, Simon Marlow wrote:
Peter Tanski wrote:
StgCRun.S is done for x86 (still need to do x86_64 and ia64). Builds fine.
What about using cpphs with GHC? I could set it up as either a program
run by ghc for 'runCpp' or as a library called by runCpp.
We've avoided cpphs so far because of the license. But if there's a good
technical reason to use it (and there does seem to be), then by all means
go ahead.
The library route would be preferable, unless it causes any licensing
headaches.
BTW, is it the practical problem of LGPL'ed Haskell code (difficulties
with dynamic linking compared to (L)GPL'ed C code like gcc, readline
etc) that is the problem, or is it the
MS-can't-touch-(L)GPL-with-barge-pole problem?
Just want to clarify what our real licensing restrictions are, given
that ghc already does bundle GPL programs (mingw) and link to LGPL
libraries (readline, gmp). If it's just the practical problem that
LGPL'ed Haskell code can't be so easily relinked as C code (stable ABI
and all that) then we might be able to ask for a static linking
exception for cpphs.
There are no real practical problems with this, as you say we already link
to LGPL libraries. But as a matter of strategy, we want to reduce our
(L)GPL dependencies.
Remember that *we* may understand the LGPL (or at least claim to :-), but
not all potential users of GHC are in this situation, and some will have to
expend resources (time and money) to determine whether they are able to use
or modify GHC safely, and retain the rights they need over the output that
GHC generates. If GHC's license situation is complex or ambiguous, the
resources required are that much greater. Ideally GHC and everything it
depends on would be BSD-licensed, and that's the direction we want to head in.
Alternatively we could bundle the cpphs program rather than using the
cpphs library. The cpphs library is LGPL, while the cpphs program is
GPL, but then cpp is GPL too. The practical problem is the same in both
cases, that MS folk can't contribute fixes for cpp(hs).
I have some misgivings about whether linking LGPL Haskell libraries is
within the spirit of the license, given that re-linking is often
impractical. But nobody else seems to care about this, I haven't seen any
authors of Haskell LGPL libraries complain that users can't easily comply
with it. I suppose the re-linking requirement isn't as critical as the
contribute-changes-back requirements, so authors are prepared to turn a
blind eye.
Malcolm, how do you feel about this? Are we able to link cpphs as a
library statically to GHC?
Cheers,
Simon
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