Comments on: Ruby vs. Haskell – project Euler #25 deathmatch

By: Ssmm987

Ssmm987 — Sun, 26 Dec 2010 15:47:49 +0000

Nice post, but personally I prefer using C#.

P.s. I blog about project euler too!

By: Atul Kash

Atul Kash — Tue, 23 Mar 2010 08:50:31 +0000

Thanks for the clarification, great article

By: ochronus

ochronus — Thu, 18 Feb 2010 14:15:22 +0000

Right, thanks for the clarification. Someone also posted a specific faster solution for this problem using simple addition – which I avoided by decision. But again, probably that’s even more imperative…

This comment was originally posted on Reddit

By: lpsmith

lpsmith — Thu, 18 Feb 2010 05:30:57 +0000

Matrix exponentiation, while a very fast way to calculate an arbitrary fibonacci number, is much slower than simple addition when all you want to do is get the next fibonacci number. However, you get *two adjacent* fibonacci numbers from one matrix exponentiation, which you can then use to get the next (or previous) number. So you might consider some kind of search (e.g. binary, although there would be better choices given the nature of the problem), combined with a linear scan once you get close enough. But really, that level of algorithmic sophistication is overkill for this particular problem…

This comment was originally posted on Reddit

By: Kevin

Kevin — Wed, 17 Feb 2010 16:59:38 +0000

Web technologies like PHP, Javascript, HTML, CSS also seem a must to learn. Even if you are not going to be a pro in these, they help when you want to maintain or tweak your website or blog.

By: rlaksana

rlaksana — Wed, 17 Feb 2010 16:13:28 +0000

Ruby vs. Haskell – project Euler #25 deathmatch – http://su.pr/9wyESj

This comment was originally posted on Twitter

By: Richard Laksana

Richard Laksana — Wed, 17 Feb 2010 15:13:28 +0000

Ruby vs. Haskell – project Euler #25 deathmatch – http://su.pr/9wyESj

By: gaze

gaze — Wed, 17 Feb 2010 06:30:14 +0000

Either way… it’s kinda silly given that there’s a closed form soln for fibonacci…

This comment was originally posted on Reddit

By: ochronus

ochronus — Tue, 16 Feb 2010 21:44:26 +0000

@Edvin Aghanian, Thanks for the kind words, but they are right that I made a mistake with choosing a title that suggests a benchmark, so that criticism is fair, I feel. I’m also happy about the constructive additions people made – and I’m glad the post proved useful

By: Edvin Aghanian

Edvin Aghanian — Tue, 16 Feb 2010 21:37:03 +0000

@ochronus, I don’t think you need to apologize. You wrote some comparison code in two languages, which resulted in a conversation and contributions from people on how to improve your code in both languages. I drew benefit from seeing some Haskell in action, and then seeing how it can be reformatted to look very elegant. Frankly, I’m amazed how negatively people react to these kinds of posts.

By: ochronus

ochronus — Tue, 16 Feb 2010 18:49:17 +0000

@Shot, and also don’t calculate 10**999 in every cycle

By: Shot

Shot — Tue, 16 Feb 2010 18:43:16 +0000

…although the actual answer to the question is obtained with

fibs.find { |f| f >= 10**999 }

By: ochronus

ochronus — Tue, 16 Feb 2010 18:40:36 +0000

@Shot, Nice one, thanks I like it!

By: Shot

Shot — Tue, 16 Feb 2010 18:36:51 +0000

Not as concise as Haskel, but based on the same idea:

fibs = Enumerator.new { |y| a, b = 0, 1; loop { y.yield a; b, a = a, a+b } }

fibs.take_while { |f| f < 10**999 }.last

By: ochronus

ochronus — Tue, 16 Feb 2010 18:17:39 +0000

@solrize, thanks for the idea, that’s right – it’s easier to comprehend.

By: solrize

solrize — Tue, 16 Feb 2010 18:13:30 +0000

I like to write:

Prelude> let fib x y = y:fib y (x+y)
Prelude> take 20 $ fib 0 1
[1,1,2,3,5,8,13,21,34,55,89,144,233,377,610,987,1597,2584,4181,6765]

That is a little easier to understand than the zip version, I think.

By: mfcastellani

mfcastellani — Tue, 16 Feb 2010 18:07:11 +0000

rt @ruby_news Ruby vs. Haskell – project Euler #25 deathmatch http://bit.ly/97bh2Y

By: ochronus

ochronus — Tue, 16 Feb 2010 17:52:09 +0000

Yes, you’re right, the same goes for almost all mathematical constructs. I only wanted to show/sugges the ease and naturalness of the Haskell representation of the Fibonacci series – which is also the basic difference (for me at this point) of the imperative and functional approaches.

This comment was originally posted on Reddit

By: ochronus

ochronus — Tue, 16 Feb 2010 17:46:13 +0000

Anyway, points taken, thanks for the comments and suggestions, I will watch out for these mistakes in my forthcoming posts.