[Haskell-cafe] Announce: Haskell Platform 8.6.5 (Gershom B) - clarification
Pierre_van_der_Laar (Functional Account)
pierre.van.de.laar at philips.com
Tue May 21 09:54:11 UTC 2019
The license issue can be summarized as follows:
Whenever a program is compiled with GHC and is distributed on another platform than OS X,
anybody can claim that the source code of that program must be provided due to the LGPL license,
since integer-gmp, the ghc code, and that program's code are statically linked!
Not convinced? Read e.g. https://gitlab.haskell.org/ghc/ghc/wikis/replacing-gmp-notes that discussed both the LGPL license and the usage of static libraries by GHC. For convenience, I have include the most relevant parts:
GMP is licensed under the GNU Lesser General Public License (LGPL), a kind of "copyleft" license. According to the terms of the LGPL, paragraph 5, you may distribute a program that is designed to be compiled and dynamically linked with the library under the terms of your choice (i.e., commercially) but if your program incorporates portions of the library, if it is linked statically, then your program is a "derivative"--a "work based on the library"--and according to paragraph 2, section c, you "must cause the whole of the work to be licensed" under the terms of the LGPL (including for free).
The LGPL licensing for GMP is a problem for the overall licensing of binary programs compiled with GHC because most distributions (and builds) of GHC use static libraries. (Dynamic libraries are currently distributed only for OS X.) The LGPL licensing situation may be worse: even though The Glasgow Haskell Compiler License is essentially a "free software" license (BSD3), according to paragraph 2 of the LGPL, GHC must be distributed under the terms of the LGPL!
So the problem is real and seems to be underestimated by the Haskell user community based on the many (partly) incorrect responses on this mailing list.
I still would like to know what GHC's strategy is to tackle this problem!
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