[Haskell-cafe] classes for data structures

[Henning Thielemann]

On Wed, 6 Feb 2008, Denis Bueno wrote:

> On Feb 6, 2008 10:36 AM, Henning Thielemann
> <lemming at henning-thielemann.de> wrote:
> > > type SomethingWithKV k a = KV {getKV :: (k, a)}
> > > instance Buildable (Map k a) (SomethingWithKV k a) where
> > >   empty = Map.empty
> > >   insert s m = uncurry Map.insert (getKV s) m
> > >
> > > I have done this before -- it's very convenient, and I think makes the
> > > code that uses empty and insert more robust, and easier to read.
> >
> > But why do you want to have the special type SomethingWithKV, but not
> > MapSomething ?
>
> Do you mean a map that maps SomethingWithKV to whatever, instead of k to v?

I mean a Map that is specialised for storing SomethingWithKV instead of
plain pairs. (If I imagine a Map as a list of pairs that is optimized for
efficiency.)