11–20 of 124 posts
I wonder why I don't often see folks directly computing Fib(n) using the equation given in SICP exercise 1.13: Fib(n) = round(φ^n / sqrt(5)), where φ = (1 + sqrt(5)) / 2. Cites: http://mitpress.mit.edu/sicp/full-text/book/book-Z-H-11.html... https://secure.wikimedia.org/wikipedia/en/wiki/Fibonacci_num...
Too bad the code is so nasty
Author here, didn't really expect this to get picked up anywhere but since it has I'd like to point out the idea was to demonstrate that computationally expensive algorithms can be split across multiple iterations of the event loop to avoid blocking it. In this case concurrent requests take advantage of each others' memoisation, which would be somewhat trickier to do with threads as you'd probably need to worry about…
I wonder why I don't often see folks directly computing Fib(n) using the equation given in SICP exercise 1.13: Fib(n) = round(φ^n / sqrt(5)), where φ = (1 + sqrt(5)) / 2. Cites: http://mitpress.mit.edu/sicp/full-text/book/book-Z-H-11.html... https://secure.wikimedia.org/wikipedia/en/wiki/Fibonacci_num...
Wow, this really made me laugh.
- Node sucks;
- No it doesn't * 2;
- Use Haskell;
- (others) ?
This one however has made me laugh as well :)
Author here, didn't really expect this to get picked up anywhere but since it has I'd like to point out the idea was to demonstrate that computationally expensive algorithms can be split across multiple iterations of the event loop to avoid blocking it. In this case concurrent requests take advantage of each others' memoisation, which would be somewhat trickier to do with threads as you'd probably need to worry about…
Yes. It is an answer to the criticism made, and I acknowledge that. But it is not a very good answer to the objection. The better answer is "don't do that in Node.js", which is still not all that great (it's really easy to accidentally write something that blocks badly), but is better.
I'd like to point out that this uses important improvements over the naive Ziuba's strawman version: memoization and callbacks using the event loop. The callbacks improve concurrency, allowing a single process/thread to multitask requests, and memoization reduces total time spent per request. Actually, if the async lib memoization facility shares values between requests, which seems quite sure to me, all requests but…
Re: Node.js, you're right. The core of the debate is whether the single-threaded, evented model is a legitimate theoretical approach to concurrency. That programming style is the same across Node.js, Tornado-web, EventMachine, etc. It translates literally to Tornado-web because the idioms are the same.
I wonder why I don't often see folks directly computing Fib(n) using the equation given in SICP exercise 1.13: Fib(n) = round(φ^n / sqrt(5)), where φ = (1 + sqrt(5)) / 2. Cites: http://mitpress.mit.edu/sicp/full-text/book/book-Z-H-11.html... https://secure.wikimedia.org/wikipedia/en/wiki/Fibonacci_num...
It’s true that another algorithm will be much faster, but that deprives us of the opportunity to discuss how this implementation of the recursive algorithm delivers much higher performance than a naïve implementation.
The back story is that an abrasive blog post asserted that Node.js was a terrible platform for certain types of problems, and this algorithm was given as an example. The author here is simply showing that with care, Node.js will not be the problem.
For shits and giggles, here’s another Fib algorithm, chosen strictly for the pleasure of implementing it:
https://github.com/raganwald/homoiconic/blob/master/2008-12-...
Take for example this implementation, how many people getting started with node knew about async or memoization?
Could be just me, but I learned a lot about what not to do and how to do certain things more efficiently with node as a result of the whole fiasco.
Thanks Ted :)