[Haskell-cafe] class default method proposal
dave at zednenem.com
Tue Dec 11 10:19:53 EST 2007
On Dec 11, 2007 9:20 AM, Duncan Coutts <duncan.coutts at worc.ox.ac.uk> wrote:
> So my suggestion is that we let classes declare default implementations
> of methods from super-classes.
> Does this proposal have any unintended consequences? I'm not sure.
> Please discuss :-)
It creates ambiguity if two classes declare defaults for a common
My standard example involves Functor, Monad, and Comonad. Both Monad and
Comonad could provide a default implementation for fmap. But let's say I
have a type which is both a Monad and a Comonad: which default
implementation gets used?
I'm disappointed to see this objection isn't listed on the wiki.
Dave Menendez <dave at zednenem.com>
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