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

David Luposchainsky dluposchainsky at
Wed Jul 10 16:02:25 CEST 2013

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.


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