[yuan]

I don't remember seeing any "dynamic typing extremists" who would argue that static typing is totally worthless, just that it has cost (e.g., it's an additional concern for the programmers) too in addition to the benefits it provides, and there are often times and cases where the cost dwarves the benefits. I do see static typing advocates who would argue that static typing should be everywhere, at all time, and non-optional.

To the extent that a single case can prove anything, what is being done here in fact strengthens the case for dynamic typing, for it shows that a dynamic language can reap the benefits of static analysis too, WHEN it is beneficial.

[jganetsk]

To the extent that a single case can prove anything, what is being done here in fact strengthens the case for dynamic typing, for it shows that a dynamic language can reap the benefits of static analysis too, WHEN it is beneficial.

You don't know that dynamic typing + static analysis is better than just static typing. Closure definitely does not catch everything. Hell, even just using the [] operator on a non-array object, Closure breaks down.