[Swift-user] Re: [Swift-devel] Problem with iterate

[Ioan Raicu]

But lets bring this back to a more real example. A user wanting to 
express some computations that have some dependencies, would write out 
their computations in some order, expecting their order to be preserved 
because of the dependencies. If you only support single assignment on 
variables (e.g. the data), then an example like the one below could 
never deadlock because the single assignment would be violated on the 
2nd statement. Perhaps things are more complicated if you support 
multiple assignments per variables, but that is not the case for Swift, 
right?

I am trying to understand if this deadlock is happening in Swift due to 
some particular implementation detail in Swift (or underlying pieces), 
or is it a fundamental flaw in the DAG based approach with single 
assignment variables? Or is it due to something completely different?

Thanks,
Ioan

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Ioan Raicu, Ph.D.
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Ben Clifford wrote:
>> Mathematically, the two different sequences evaluate to different values:
>>
>> x = y + 1
>> y = x + 1
>>
>> assuming y = 0, x = 1
>>     
>
> I mean in simultaneous equations (linear algebra) - in other words, "find 
> (through whatever means you care to use) a value of x and y such that the 
> above two equations are both satisfied" - there is no value of x and y 
> that satisfies that.
>
>   
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