2013/12/14 Simon Hengel
Hi! I propose to add
die :: String -> IO () die err = hPutStrLn stderr err >> exitFailure
to System.Exit.
Reasoning:
(1) It's a frequently required functionality. Almost every command-line program has code similar to this.
(2) The definition is relatively short, but in addition to the definition, you need two import statements.
(3) It's frequently done wrong (e.g. writing to stdout instead of stderr, or not using exitFailure, or both).
I haven't done any extensive research on Hackage, but I quickly looked at Haddock. Here we have a definition of die [1], but we also print to stdout at a couple of place and then call exitFailure [2].
Personally, I think it should be re-exported from Prelude. But this may be controversial. So let's have two separate votes:
Isn't your `die` function a special case of `error :: String -> a`, which is in the Prelude ? I think variants of what you propose are often used: different exit codes, not exiting and flushing stderr, displaying an arbitrary `Show a` instead of `String`, using `Text`, and so on. Actually I think some (all ?) `IO` things from the Prelude should not be in the Prelude. For instance I may want to use the `bytestring` `readFile`. - 1 (for both) Thu