Safe use of unsafeCoerce?

[Duncan Coutts]

On Mon, 2004-04-26 at 15:42, Alastair Reid wrote:
> > I'm after advice on whether the following example is a safe use of
> > unsafeCoerce, and if it is safe, if it's worth it.
> 
> It looks like it is safe but it feels like using a sledgehammer to crack a 
> nut ... in the presence of small children/ curious animals/ two left thumbs/ 
> etc. so you have to take great care that none of them are near the nut each 
> time you pull that sledgehammer out.
> 
> Given the function castFooToBar (which you tell us is safe), there's a number 
> of obvious typesafe ways of writing this code, why not do so?  [I accept that 
> there could be some reasons I just didn't see you mention any.]

In the context of the Gtk class hierarchy, we do currently have a type
safe way of doing it (wrapBar.castForiegnPtr.unwrapFoo), but I'm trying
to eliminate the class dictionary overhead.

I'm open to other suggestions.

Duncan