Proposal: overhaul System.Process

Neil Mitchell ndmitchell at
Tue Apr 29 15:58:19 EDT 2008


> > Surely in this case one wants stdout in a separate String to stderr?
> >
> > If something fails in the middle of a long operation, I want just the
> > error, doc!

Sometimes what you want is the ordered sequence, so you can see which
out message came just before the err message. You could just
generalise to:

IO (ExitCode, String, String, String)

where ( _, out `intersperse` err, out, err)

But that feels a little ugly

>  How about two separate versions?  In which case, what should they be
> called?

The current proposal feels very good. You have the "I expect it to
fail" and the "I expect it to succeed". If you introduce another
variant, it suddenly becomes much less clear.



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