[Haskell-cafe] Re: Lock-Free Data Structures using STMs in Haskell

[Pete Kazmier]

Bryan O'Sullivan <bos at serpentine.com> writes:

> Pete Kazmier wrote:
>
>>   data ArrayBlockingQueueSTM e = ArrayBlockingQueueSTM {
>>     [...]
>>     sa :: Array Int (TVar e)
>>   }
>> 
>> It's unclear to me why the Array's elements must be wrapped in TVars.
>
> To allow them to be modified.  You can't otherwise modify the elements
> of an array without going into the ST monad.

Thanks!  I forgot about the whole immutable thing :-)  Haven't used
arrays yet while learning Haskell!