[Haskell-cafe] Having trouble with instance context

[Kurt Stutsman]

Stephen Tetley wrote:
> On 23 February 2011 15:40, Kurt Stutsman <kstutsman at gmail.com> wrote:
>
>   
>> instance Enum e => Serializable e where
>>   get mask = {- convert mask to Int and then to a BitSet -}
>>   put bitset = {- convert BitSet to Int and then to String -}
>>
>>     
>
> I looks like all you need is for objects to be enumerable, i.e have
> instances of Enum. So instead of the above class, can you manage with
> these two functions?
>
> get :: Enum e => e -> Int
>
> put :: BitSet -> String
>
> Type classes give you type-based dispatch - *but* they are overkill if
> you don't actually need type-base dispatch.
>
>   
I need to support non-enumerable data types as well. That's why I wanted 
the Serializable class. For those non-enumerable types, I can create a 
custom instance of the Serializable class. But for Enums, I will always 
do the same thing, so implementing Serializable for all Enum types is 
really overkill.