[Haskell-cafe] Why does this work: 'instance Num (Show a) where'
Ivan Lazar Miljenovic
ivan.miljenovic at gmail.com
Tue Nov 4 09:46:08 UTC 2014
Is there a corresponding Show datatype?
At least with 7.8.3, having just that line gives the following error:
The first argument of ‘Num’ should have kind ‘*’,
but ‘Show a’ has kind ‘Constraint’
In the instance declaration for ‘Num (Show a)’
On 4 November 2014 19:30, Tom Ellis
<tom-lists-haskell-cafe-2013 at jaguarpaw.co.uk> wrote:
> This is accepted by GHC 7.6.3. Is this a bug? What does it mean?
>
> instance Num (Show a) where
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Ivan Lazar Miljenovic
Ivan.Miljenovic at gmail.com
http://IvanMiljenovic.wordpress.com
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