[Haskell-cafe] Phantoms
Jules Bean
jules at jellybean.co.uk
Fri Aug 15 02:00:54 EDT 2008
Malcolm Wallace wrote:
> Andrew Coppin <andrewcoppin at btinternet.com> wrote:
>
>>> instnace Show (Foo Int) ...
>>> instnace Show (Foo Double) ...
>>>
>> ...WHY did I not think of this myself? o_O
>
> Because it is not Haskell'98?
> It requires {-# LANGUAGE OverlappingInstances #-}
No it doesn't?
It requires the much more semantically simple -XFlexibleInstances, as
far as I know.
Overlapping would only be needed if there was also a polymorphic
instance on Foo a?
Jules
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