Overloadable list type notation

[Edward Kmett]

On Tue, Feb 17, 2015 at 1:14 PM, Alexander Berntsen <alexander at plaimi.net>
wrote:

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> On 17/02/15 05:30, Greg Weber wrote:
> > I had an idea whose goal is to ease people into Foldable,
> > Traversable, etc. There could be a notation that shows the
> > generalization that is occurring.
> >
> > map :: Functor [_] => (a -> b) -> [a] -> [b]
> >
> > This means that the syntax for the list type is now syntax for the
> > variable created by the Functor constraint.
> I don't know how useful this is by itself.
>
> What I *really* want is list-style syntax sugar for pattern matching. I.e.
>
>   f = \xs  -> case xs of
>     []     -> foo
>     [x]    -> bar x
>     [x:y]  -> fu  x y
>     (x:xs) -> baz x xs
>
>
The existing IsList machinery gets you the [], [x], and [x,y] cases, but
not (x:xs).

-Edward
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