PROPOSAL: Add displayException to Exception typeclass

[Felipe Lessa]

On 11-11-2014 04:40, Andreas Abel wrote:
> +1 for providing an easy way to install an exception handler that uses
> the display function.
>
> You could consider to just provide
>
>   displayExceptionHandler :: SomeException -> IO ()

Even better, why not

  stderrExceptionHandler
    :: (SomeException -> String) -> SomeException -> IO ()

Then it's trivial to define:

  defaultExceptionHandler = stderrExceptionHandler show
  displayExceptionHandler = stderrExceptionHandler display

Or anything else you may want, for that matter.  In particular:

  foobarExceptionHandler = stderrExceptionHandler mkMsg
    where
      ruler = replicate 60 '-'
      mkMsg exc =
        unlines
          [ ruler
          , "Sorry, an unexpected error occurred.  Please "
          , "file an issue at https://bugs.example.com/"
          , "with the following message attached:"
          , ruler
          , display exc -- Use both for
          , show exc    -- good measure :P.
          , ruler ]

An easy way of installing a custom exception handler that directs the
user towards the application's developers :).

Cheers,

-- 
Felipe.

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