[mercury-users] Event handling in mercury

[Fergus Henderson]

On 17-Jul-2001, Ralph Becket <rbeck at microsoft.com> wrote:
> I think Fergus idea of adding a `:- global' directive to the language is
> a good one (I assume access to globals could only occur in contexts
> where the io__state is available?)

Yes. 

My idea was that the values stored in globals would only be accessible
via io_store__get_mutvar, which requires an io__state pair:

        :- pred io_store__get_mutvar(mutvar(T, io_store), T, io__state, io__state).
	:- mode io_store__get_mutvar(in, out, di, uo) is det.

If we use a type class based approach, as Holger Krug has proposed, then the
details would be different, but your assumption would remain correct.

-- 
Fergus Henderson <fjh at cs.mu.oz.au>  |  "I have always known that the pursuit
The University of Melbourne         |  of excellence is a lethal habit"
WWW: <http://www.cs.mu.oz.au/~fjh>  |     -- the last words of T. S. Garp.
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