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

Henning Thielemann lemming at
Mon Jul 15 18:32:47 CEST 2013

On Mon, 15 Jul 2013, Sturdy, Ian wrote:

> Consider also among unquestionably useful instances that violate simple 
> prejudice the Num instance for `Num a => Set a`, where `a + {1,-1} - 
> {1,-1} == {a-2,a,a+2}`.

That's the main reason why a Num instance of Sets is a bad idea. If you 
continue that way you will soon end up in MatLab mess. In MatLab every 
number is actually a complex valued matrix.

So will the next proposal be an 'instance IsString (Set a)'? Or 'instance 
IsString [a]' (for every a/=Char)?

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