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

This is really cool. The blog post [3] finally explained to me why I had so much difficulties implementing the Equal constructor ;) I shared this in a previous thread: http://osdir.com/ml/haskell-cafe@haskell.org/2010-06/msg00369.html Maybe latter I'll shift to a class type based DSL. They seem more generic than data type based. Corentin On Thu, Oct 28, 2010 at 2:02 PM, steffen wrote:

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 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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