Re: Fwd: [Haskell-cafe] DSL libraries

7 Nov 2010

      Hey,

Sorry, hard week and I haven't had time to look into it until now. I
remember having had the very same Problem with AwesomePrelude. A very
quick fix for me was to remove the "Lang.*" and "Compiler.*" entries
in "exposed-modules" in the cabal file. You won't really need them
anyway.

If you really want to try AwesomePrelude, you may find the need to
changes some parts of it. For example, the AwesomePrelude's Num class
implies a Show instance, which can be very annoying. So best is to use
it as base for your own code and steal from it what you will need or
create your own version of AwesomePrelude according to your own
needs.

For example calling "test" in this example[1] will print out "num" and
when defining your own Show-Instance your program won't compile due to
overlapping instances.

The same example using AwesomePrelude with associated data families[2]
introducing new types for every aspect of your DSL  will look like [3]
(See the Lang.* Modules for more examples and evaluation, for this
kind of type safe DSL).

[1] https://gist.github.com/666119
[2] https://github.com/urso/AwesomePrelude
[3] https://gist.github.com/666121

On 4 Nov., 18:51, Dupont Corentin  wrote:
...
Nobody had the compilation messages I had?
---------- Forwarded message ----------
From: Dupont Corentin 
Date: Tue, Nov 2, 2010 at 2:30 PM
Subject: [Haskell-cafe] DSL libraries (Was: Map constructor in a DSL)
To: steffen , haskell-c...@haskell.org
Hello Steffen,
can you compile AwesomePrelude?
I've got error messages (see below).
By the way, I've looked at some DSLs made in Haskell, if I don't mistake
there are lots of similarities between them.
There similarities could be put in a library to help the implementors of a
DSL, more or less like AwesomePrelude.
Is there already packages on Hackage dealing with that?
Cheers,
Corentin
AwesomePrelude compilation error:
I'm using GHC 6.12.1.
...
cd tomlokhorst-AwesomePrelude-9819315
cabal install
(...)
Warning: Lang.Haskell: Instances of type and data families are not yet
supported. Instances of the following families will be filtered out:  H
Then, when trying with a very simple GATD in GHCI, I've got:
<interactive>: HSAwesomePrelude-0.1.0.o: unknown symbol
`AwesomePreludezm0zi1zi0_
CompilerziLiftDefinitions_inline_closure'
ghc: unable to load package `AwesomePrelude-0.1.0'
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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