Okay - but then you can keep state in haskell by using a driver thread
and channels like in the example I posted. I guess I should have said
it is best practice to check the real state rather than a (possibly wrong)
copy.
Keean.
Benjamin Franksen wrote:
On Tuesday 23 November 2004 10:39, Keean Schupke wrote:
Adrian Hey wrote:
This is one situation, but certainly not the only possible one. You have
the same problem with interfacing to any unique stateful resource (or
even if you have a multiple but finite supply of these resources).
No you don't... Most devices have registers, those registers contain
values, you can inspect those values to see if the device has been
initialised. You can then write a guard on the initialisation that really
checks if the device has (or hasn't) been initialised rather than rely
on some
'shadow' copies in RAM.
Alas, unfortunately not every device is designed in this way (I can give
examples if you want). Adrian is right in that there is not only badly
designed C libraries but also badly designed hardware!
Ben
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