[Haskell-cafe] Recommended class instances for container type

Christoph Breitkopf chbreitkopf at googlemail.com
Thu Dec 8 17:12:06 CET 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
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