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

Herbert Valerio Riedel hvriedel at
Thu May 21 16:07:57 UTC 2015

On 2015-05-21 at 18:02:57 +0200, Brandon Allbery wrote:
> On Thu, May 21, 2015 at 11:51 AM, Herbert Valerio Riedel <hvriedel at
>> wrote:
>> Performance isn't (my) motivation for avoiding fork/exec (and the
>> equivalent on Win32) but rather avoiding the added complexity of
>> marshalling/IPC with fork/exec, as opposed to simply calling into a
>> native Haskell function and crossing process boundaries and having to
>> deal with the various things that can go wrong with the additional
>> moving parts you encounter when controlling an external process. So this
>> would IMO simplify code paths, and moreover I'd expect opportunities to
>> actually make the Haskell cpphs API richer (in case it isn't already)
>> and more tailored to GHC's lexer/parser pipeline and error-reporting.

> Don't you still have to support -pgmF?

I guess so, unfortunately... so we'd have to keep a legacy code-path for
external cpp processing around, at least in the short run...

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