SV: [Haskell-cafe] RFC: "Native -XCPP" Proposal

[Boespflug, Mathieu]

[ Dropping wrong address for Malcolm. ]

--
Mathieu Boespflug
Founder at http://tweag.io.

On 8 May 2015 at 12:05, Boespflug, Mathieu <m at tweag.io> wrote:

> I'm unclear why cpphs needs to be made a dependency of the GHC API and
> included as a lib. Could you elaborate? (in the wiki page possibly)
>
> Currently, GHC uses the system preprocessor, as a separate process.
> Couldn't we for GHC 7.12 keep to exactly that, save for the fact that by
> default GHC would call the cpphs binary for preprocessing, and have the
> cpphs binary be available in GHC's install dir somewhere?
>
> fork()/execvce() is cheap. Certainly cheaper than the cost of compiling a
> single Haskell module. Can't we keep to this
> separate-(and-pluggable)-preprocessor-executable scheme? We'd sidestep most
> license tainting concerns that way.
>
>
> On 8 May 2015 at 11:39, Herbert Valerio Riedel <hvriedel at gmail.com> wrote:
>
>> Hello,
>>
>> On 2015-05-08 at 11:28:08 +0200, Niklas Larsson wrote:
>> > If the intention is to use cpphs as a library, won't the license
>> > affect every program built with the GHC API? That seems to be a high
>> > price to pay.
>>
>> Yes, every program linking the `ghc` package would be affected by
>> LGPL+SLE albeit in a contained way, as it's mentioned on the Wiki page:
>>
>> | - As a practical consequence of the //LGPL with
>> static-linking-exception//
>> |   (LGPL+SLE), **if no modifications are made to the `cpphs`-parts**
>> |   (i.e. the LGPL+SLE covered modules) of the GHC code-base,
>> |   **then there is no requirement to ship (or make available) any source
>> code**
>> |   together with the binaries, even if other parts of the GHC code-base
>> |   were modified.
>>
>> However, don't forget we already have this issue w/ integer-gmp, and
>> with that the LGPL is in full effect (i.e. w/o a
>> static-linkage-exception!)
>>
>> In that context, the suggestion was made[1] to handle the cpphs-code
>> like the GMP code, i.e. allow a compile-time configuration in the GHC
>> build-system to build a cpphs-free (and/or GMP-free) GHC for those
>> parties that need to avoid any LGPL-ish code whatsoever in their
>> toolchain.
>>
>> Would that address this concern?
>>
>>
>>  [1]:
>> http://www.reddit.com/r/haskell/comments/351pur/rfc_native_xcpp_for_ghc_proposal/cr1cdhb
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>
>
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