Proposal: overhaul System.Process

Simon Marlow marlowsd at
Tue Apr 22 18:45:27 EDT 2008

Bryan O'Sullivan wrote:
> Neil Mitchell wrote:
>> I would have thought (ExitCode,String) was more appropriate.
> Yes, definitely.

Good point.  Although I'm not sure I'm keen on readProcess being lazy 
(but you can have a lazy variant if you want).

> What happens to stderr with this function, by the way?
>  Is it tied to stdout (probably the right thing to do), or to /dev/null,
> or is it closed (eek!)?  

None of the above :)  Currently it's inherited from the parent. 
Unfortunately it's not easy to tie stderr and stdout to the same pipe - 
createProcess can't do that, and readProcess is defined in terms of it.

 > It would be useful if there was a readProcess variant that gave back a
 > String each for stdout and stderr.

Would it be reasonable for that to be the only variant?


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