Proposal: overhaul System.Process

David Roundy droundy at darcs.net
Sat May 24 08:13:03 EDT 2008


On Fri, May 23, 2008 at 08:22:56PM +0100, Duncan Coutts wrote:
> 
> On Fri, 2008-05-16 at 15:44 +0100, Brian Brunswick wrote:
> > On Thu, May 15, 2008 at 10:45 AM, Simon Marlow <marlowsd at gmail.com> wrote:
> > > The latest version of the Process overhaul is here:
> > >
> > >
> > >  - changes to readProcess, and added readProcessWithExitCode,
> > >    as discussed on the list.
> > >
> > 
> > I'd just like to argue briefly again against merging stdout and stderr.
> 
> I think I agree. A more sensible default would be to discard stdout
> completely or to use the inherited stderr. Though exactly which depends
> on the context unfortunately.
> 
> For Cabal we have a function like readProcess and it discards stderr.
> This seems to be the right thing for the various uses in Cabal (except
> stupid "python -V" which prints the version number to stderr).

I'd vote for inherited stderr instead, as otherwise it can be very hard for
users (or developers!) to debug what goes wrong with an external command.
-- 
David Roundy
Department of Physics
Oregon State University


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