Proposal: Continue the displayException program

Several years ago, Michael Snoyman proposed [*] that we add a displayException method to the Exception class, and that we make GHC use it in the default handler. The first part of that proposal was accepted and implemented, but the second part was not, for reasons that are not very clear to me. I would like to re-propose that we change the default exception handler to use displayException instead of Show. This seems like a much better default, and anyone who wants to do it the old way can still change the top-level handler. [*] https://mail.haskell.org/pipermail/libraries/2014-November/024176.html