[Haskell-cafe] Re: Map constructor in a DSL

[steffen]

I think you would love to have a look at AwesomePrelude[1] or a fork
of AwesomePrelude using associated types[2]
Some more background information by Tom Lokhorst [3][4].

[1] http://github.com/tomlokhorst/AwesomePrelude
[2] http://github.com/urso/AwesomePrelude
[3] http://tom.lokhorst.eu/2009/09/deeply-embedded-dsls
[4] http://tom.lokhorst.eu/2010/02/awesomeprelude-presentation-video

On 28 Okt., 12:09, Dupont Corentin <corentin.dup... at gmail.com> wrote:
> Thank you for your rich responses.
>
> Indeed I think I miss some thinks in my DSL, that would make things easier
> to deal with lists and first class functions.
> I don't really know what for now.
> Perhaps a List Constructor? Or a constructor on functions like yours Ryan?
> EAp :: Exp ref (a -> b) -> Exp ref a -> Exp ref b
> It's from which DSL? It is accessible on the net?
>
> Chris suggested me that I can only define the Foldr constructor and deduce
> Map from it.
> But maybe I have to add a List constructor for that.
>
> But in the suggestions from Ryan and Brandon I don't understand why I should
> add an extra type parameter and what it is!
>
> Steffen: Wow nice. I'll integrate that ;)
>
> I'm also looking at the Atom's DSL to get inspiration.
> Something I don't understand in it is that it has two languages, on typed:
>
> data E a where
>   VRef    :: V a -> E a
>   Const   :: a -> E a
>   Cast    :: (NumE a, NumE b) => E a -> E b
>   Add     :: NumE a => E a -> E a -> E a
> etc.
>
> And, along with it, an untyped counterpart:
>
> -- | An untyped term.
> data UE
>   = UVRef UV
>   | UConst Const
>   | UCast  Type UE
>   | UAdd   UE UE
> etc.
>
> What that for? What's the use of having beautiful GADT if you have to
> maintain an untyped ADT aside??
>
> Corentin
>
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