important news: refocusing discussion
Malcolm.Wallace at cs.york.ac.uk
Mon Mar 27 06:13:29 EST 2006
John Goerzen <jgoerzen at complete.org> wrote:
> On Fri, Mar 24, 2006 at 11:07:53AM +0000, Malcolm Wallace wrote:
> > I assume that since a non-concurrent implementation has
> > only one thread, that thread will be trying to MVar-synchronise with
> > something that does not exist, and hence be blocked for ever.
> Not necessarily. An MVar is a useful tool in place of an IORef. It
> works well when a given hunk of code is used in a threaded program,
> but it also works well in a non-threaded program. If they are used
> correctly, there is no problem.
Your final sentence is the one that I want to emphasise. What does it
mean to use an MVar "correctly", such that one can avoid blocking in a
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