On Tue, Apr 22, 2008 at 04:09:56PM -0700, Don Stewart wrote:
duncan.coutts:
On Tue, 2008-04-22 at 15:52 -0700, Don Stewart wrote:
duncan.coutts:
I would have thought (ExitCode,String) was more appropriate.
Yes, definitely.
Yes, I mentioned this to Don previously when he published his popen code. I think he agreed.
I'd changed, but not pushed out, process-light:
readProcess :: FilePath -- ^ command to run -> [String] -- ^ any arguments -> String -- ^ standard input -> IO (Either (ExitCode,String) String) -- ^ either the stdout, or an exitcode and any output
You don't need the Either. ExitCode already covers the case when the process terminates successfully.
But we want to force people to check the failure case. Just returning the tuple doesn't help there.
But it is much more elegant, cleaner code, and more in line with the underlying semantics. A general library API shouldn't force complexity on its users. Also, it has two redundant cases (Left (ExitSuccess,out)) and (Right out), which is a far worse bug in an API. Also, it means you can't have lazy output. since you won't know the error code until the process has finished completely. John -- John Meacham - ⑆repetae.net⑆john⑈