Discussion: adding displayException to Exception class

[Michael Snoyman]

On Wed, Oct 29, 2014 at 10:45 AM, Simon Peyton Jones <simonpj at microsoft.com>
wrote:

>  As I recently commented on this list[1], the Show typeclass is
> overloaded with multiple meanings (serialization, debug info, and
> user-friendly data display). The general consensus seems to be that the
> official semantics for Show should be for serialization (as paired up with
> Read).
>
>
>
> Really?  My instinct is otherwise: *to use Show for human-readable
> display, and Binary for serialisation*.  Show/Read is a terribly
> inefficient serialisation format; as soon as you want to do it for real you
> end up with Binary anyway.  And Show is already well established for
> human-readable purposes – that was one of its primary original purposes.
>
>
>
> Simon
>
>
My weak vote in that thread went towards Show for human-readable display,
but there was some quite harsh objection to that position. In this thread
too you can see people wanting a direct encoding of types which can be
copy-pasted into a Haskell source file. Personally, I don't see much need
for that, and especially given the new ability to essentially auto-derive
Binary instances (via Generic), Show/Read serialization seems fairly
pointless.

Nonetheless, making a proposal that doesn't enforce a changed semantics on
the Show typeclass seems like the path of least resistance. If others want
to jump back into the previous topic and try to hammer down the ideal usage
of the Show typeclass, I'm happy to participate in that discussion too.

Michael
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