Overlapping and incoherent instances

[Stephen Paul Weber]

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>instance {-# OVERLAPPABLE #-} Show a => Show [a] where ...
>
>instance {-# OVERLAPPING #-} Show [Char] where ...

This, to me, is an admission that developers are not going to want to turn 
overlapping on globally in general, and so the current language extensions 
would not make sense to get adopted into the core language at any point.  
I agree with this idea, and so would second the proposal mentioned at 
<http://www.reddit.com/r/haskell/comments/2c136i/xoverlappinginstances_and_xincoherentinstances_to/cjb4jmr> 
that a language extension that adds actual keywords to tag instances that 
should be allowed to overlap be added, instead of resorting to pragmas.  
This seems like an approach that could be useful in general and one could 
imagine moving "past" an extension to the core language at some point, 
potentially.

- -- 
Stephen Paul Weber, @singpolyma
See <http://singpolyma.net> for how I prefer to be contacted
edition right joseph
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