Proposal: die to System.Exit (and/or Prelude)

[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:

Add System.Exit.die:            +1
Re-export it from Prelude:      +1

(discussion until December, 28th)

Cheers,
Simon

[1] https://github.com/ghc/haddock/blob/8d4c94ca5a969a5ebbb791939fb0195dc672429e/src/Haddock/Utils.hs#L303
[2] https://github.com/ghc/haddock/blob/c6faeae064668125721b0d5e60f067f90c538933/src/Haddock.hs#L87