[Haskell-cafe] How to variables

[robert dockins]

>>Some people may suggest that you to create top-level IORefs using
>>unsafePerformIO, but I don't recommend that for this situation.
> 
> 
> Well I can't imagine which particular people you have in mind :-)
> 
> But, as a vocal advocate of sound support for top level mutable
> state, I would just like to go on record as saying I certainly
> would not advocate it for this problem.
> 
> But then again, I wouldn't advocate the use of explicit "entire
> program state" record passing either :-)

Fair enough.  The main reason I suggested it is a fairly painless way to 
emulate global variables within a main control loop, which was the OPs 
stated goal.  ("it's important to implement it in as most imperative 
form as possible...")

I would personally attempt to adopt a more functional way of approaching 
the problem (Arrows and whatnot), but those are still pretty murky waters.