[Haskell-cafe] Recommended class instances for container type

[Edward Z. Yang]

I'd hazard that if you went 'containers' and looked at what instances were
implemented, that would give you a good idea. :^)  (For example,
if you look at Data.MAp, it has NFData, Typeable2 and Data instances.)

Edward

Excerpts from Christoph Breitkopf's message of Thu Dec 08 11:12:06 -0500 2011:
> Hello,
> 
> I'm in the process of implementing a container data type, and wonder what
> class instances are generally considered necessary. E.g. is it ok to start
> out with a Show that's adequate for debugging, or is it a 'must' to include
> instances of everything possible (Eq, Ord if possible, Read, Show, Functor,
> ...).
> 
> And what about the more experimental things? Say, DeepSeq, Typeable, Data?
> I'd like to keep this simple at start, and I've admittedly not followed
> recent developments in Haskell-land (recent meaning the last 10 years or
> so. I _do_ know about hierachical modules ;-) ).
> 
> OTOH, if not having such instances makes it impossible to do things the
> modern way, I'd probably take the time to implement (and maybe understand)
> them.
> 
> Thanks,
> 
> Chris