Linked by Thom Holwerda on Sat 19th Aug 2006 16:11 UTC
Microsoft MSDN's Channel 9 has two videos in their 'Going Deep' series which dive, well, deeper into Singularity, the operating system in development at Microsoft's research department. The first of the two is about, among other things, Software Isolated Processes (SIPs). The second of the two actually shows Singularity in action.
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RE[5]: R&D
by grayrest on Sat 19th Aug 2006 22:08 UTC in reply to "RE[4]: R&D"
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How about another example?

The point wasn't to distinguish between pass-by-reference and pass-by-value, in fact, the entire reason that distinction is necessary is because the language has side effects.

Consider the snippet:

x = 1
x + 2
print x
x = 2
print x

The output of the first print statement is 1, even though it comes after an addition operation on x, the value is 1 because addition is an operation with no side effects.

Now consider the second assignment operation. Whatever value was previously in x is now gone, the value of x is now 2. This is called a destructive update. The state of x is modified so that future references to x (the print statement) will now get the value 2.

In a language without side effects, any past or future reference to x will always retrieve the same value. Similarly, functions will always return the same value given the same inputs, this is the concept of referential transparency.

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