Simon Marlow [EMAIL PROTECTED] wrote,
data Point
foreign import getMousePos :: Ptr Point - IO ()
foreign import getX :: Ptr Point - IO Int
foreign import getY :: Ptr Point - IO Int
vs
data Point = Point (Ptr Point)
foreign import getMousePos ::
ok, I'm convinced. The semantics of empty datatypes can be a type inhabited
only by bottom.
Hugs implements exactly that.
[Except in the special case of a few magical names (Int, Float, etc) when they
occur in the Prelude (and only then). Since it is only usable in the
Prelude, they can be
Ross Paterson [EMAIL PROTECTED] wrote,
Minor nits: there's a footnote saying Finalizers in Haskell cannot
be savely [sic] realised without requiring support for pre-emptive
concurrency. I'd suggest dropping pre-emptive: with cooperative
concurrency it's perfectly safe to collect the
Simon Marlow [EMAIL PROTECTED] wrote,
Manuel M T Chakravarty [EMAIL PROTECTED] writes:
-=- Changes since RC 9
* 6.2: All the types in CTypes must be newtypes that are exported
abstractly.
This change makes things highly inconvenient in nhc98. A newtype
can
* 6.2: All the types in CTypes must be newtypes that are exported
abstractly.
How about exporting them non-abstractly for nhc98 only, and adding a
comment to explain why the workaround is necessary?
That's what I prefer, too.
OK, that's what I've done. The spec can
Simon Marlow [EMAIL PROTECTED] wrote,
We routinely use code like this:
data Point
foreign import getMousePos :: Ptr Point - IO ()
foreign import getX :: Ptr Point - IO Int
foreign import getY :: Ptr Point - IO Int
The idea being that:
1) there is a foreign type
Let's be clear about the role of Point here: it is a dummy type
argument to Ptr, used to disambiguate the type 'Ptr Point' from any
other kind of Ptr. It is for type-safety in the Haskell code.
It doesn't matter how many values of the type Point there are. I could
use any Haskell
data Point
foreign import getMousePos :: Ptr Point - IO ()
foreign import getX :: Ptr Point - IO Int
foreign import getY :: Ptr Point - IO Int
vs
data Point = Point (Ptr Point)
foreign import getMousePos :: Point - IO ()
I like the second idiom. You are
On Wed, Jun 04, 2003 at 11:09:43PM +1000, Manuel M T Chakravarty wrote:
StablePtr are used to export references to Haskell values to
C, where they are treated as abstract data. In C one
traditionally uses (void *) for that purpose (see man
qsort(3)). We want to make sure HsStablePtr is not
