Re: [Haskell-cafe] Having trouble with instance context

Stephen Tetley wrote:

On 23 February 2011 15:40, Kurt Stutsman 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.