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Comment by khaledh | Hacker News Reader

That's not true. The lambdas used in the functional version are each called once for every item in the list.

No sane optimizer is going to emit the functional code as a gajillion function calls.

True, but now you're relying on a specific implementation and optimization of the compiler, unless the language semantics explicitly say that lambdas will be inlined.

This is true of literally anything and everything your compiler emits. In practice the functional style is much easier to optimize to a far greater degree than the imperative style.

This is why you shouldn't get into arguments about performance on the internet without highly specified execution environments.

I'm going to take my own advice and go back to work :)

Yeah, if you treat it as javascript vs python they're likely correct (I'm not that familiar with js). The article and original comment were about function vs imperative though, so I assumed half decent runtimes for both.

It's not? How could that possibly work when the lambda could throw and it could throw on the nth invocation and your stack trace has to be correct?

If I run this in the JS console I get two anonymous stack frames. The first being the console itself.

    [1, 2, 3].filter(x => [][0]())

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