data-default WAS: [containers] Proposal: Change to the Data.Map Monoid

John Meacham john at
Thu May 29 21:17:34 UTC 2014

On Thu, May 29, 2014 at 9:44 AM, Bryan O'Sullivan <bos at> wrote:
> Yes, of course we should. The whole point of having typeclasses is that the
> instances should make sense for everyone. The bar for introducing both
> typeclasses and especially automatically derived instances is a whole lot
> higher than "works for me, sometimes".

I think a lot of early haskell programmers are very biased towards
type classes when higher order functions are a much better solution to
a given problem.

You can write automatic deriving code for user classes directly now:

currently GHC only, but as soon as type families are solid It's
definitely something I'm putting into jhc.


John Meacham -

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