FFI Definition

[Simon Peyton-Jones]

[Welcome back, Sigbjorn.  Are you on the FFI mailing list?    
Now you are back online you should be!]

| Export dynamic introduces a name, export static exports an 
| existing name. For that reason putting this distinction in 
| extent seems strange for me.

This seems like a good point to me.

    foreign export foo :: Int -> IO Int
	exports a C-callable function foo
	*uses* a Haskell function  foo :: Int -> IO Int 
		(that is, foo must be in scope)

    foreign export dynamic baz :: (Int -> IO Int) -> IO Addr
	does not export anything to C
	*defines* a Haskell function baz with the type specified
		(that is, the foreign decl binds baz)

This is rather different to 'foreign import' vs 'foreign import dynamic'
both of which import a function, but the type of the function depends
on whether it's dynamic.


PRINCIPLE: it should be possible to look at a foreign decl, and 
*without looking at the extent string* say what Haskell function is
used or defined, and what its type is.   

CONCLUSION: we need to say outside the extent string whether
we are doing foreign export or foreign export dynamic.  I'm not
sure what the right syntax is

Simon