Proposal: Add IsString instance for (Maybe a) to base

[Roman Cheplyaka]

* David Luposchainsky <dluposchainsky at googlemail.com> [2013-07-10 16:02:25+0200]
> On 2013-07-10 15:55, Joachim Breitner wrote:
> > Hi,
> > 
> > Am Mittwoch, den 10.07.2013, 09:21 +1000 schrieb Ivan Lazar Miljenovic:
> >> -0.5 from me; I think it's too easy to forget that it's a Maybe value
> >> there when refactoring, etc.
> > 
> > same here; even with OverloadedStrings Haskell should feel as strongly
> > typed as it is.
> 
> Agreed. Overloaded strings should be reserved for things that *are*
> strings in a certain way. A "Maybe String" is not a special way of
> storing a string (like for example a "Vector Char"), it's a String with
> an additional value. Providing a Maybe instance goes too far in the
> direction of having a general "'return' with strings" function, so I'm
> -1 on this.

I concur.

Roman