[Haskell-cafe] Byte Histogram

[Ivan Lazar Miljenovic]

On 8 February 2011 23:25, John Lato <jwlato at gmail.com> wrote:
>> class Container c where
>>     type Elem c :: *
>>
>> class (Container cIn, Container cOut) => CMap cIn cOut where
>>     cmap :: (Elem cIn -> Elem cOut) -> cIn -> cOut
>>
>> instance (a ~ Elem (c a), b ~ Elem (c b), Functor c, Container (c a),
>> Container (c b)) => CMap (c a) (c b) where
>>     cmap = fmap

I'm not sure if that will work for types like Set, as you're not
explicitly bringing the constraint in.

-- 
Ivan Lazar Miljenovic
Ivan.Miljenovic at gmail.com
IvanMiljenovic.wordpress.com