Standarize GHC.Prim.Any

[Isaac Dupree]

Maciej Piechotka wrote:
> I'm so sorry if I've done it wrong - it's my first contact with Haskell
> standardization and I base on
> http://hackage.haskell.org/trac/haskell-prime/wiki/Process . I hope it
> is not too late as well.

Do not worry about that, we have decided to have a yearly 
standardization process.

> Any from GHC.Prim makes unsafeCoerce much useful and safe. Can it be
> included in Unsafe.Coerce module?
> 
> Pros:
> - unsafeCoerce is much more useful with Any (it's a safe placeholder for
> any value and therefore can be passed simply in/out FFI).

Yes it's a safe placeholder, but so is an existential, I believe...
data ContainsAny = forall a. ContainsAny a
to put in the container:
"ContainsAny x"
to remove from the container:
"case ... of ContainsAny x -> unsafeCoerce x"
Albeit, there might be a slight performance penalty for the extra box, 
which can't be removed in all haskell implementations.

Also, what do you mean about "FFI"?  I don't think you can pass the 
"Any" type to foreign functions through the FFI...

Also, can/do all compilers that implement unsafeCoerce implement a safe Any?
Hugs can do it with just "data Any = Ignored" I believe, not sure about 
nhc, yhc or jhc...

-Isaac