[Haskell-cafe] Style
Hi, I defined several functions for calculating the number of trailing zero's of n! tm = sum . takeWhile(0) . iterate f . f where f = flip div 5 tm1 n = sum . takeWhile(0) . map (div n . (5^)) $ [1..] tm2 n = sum . takeWhile(0) . map (div n) $ iterate ((*)5) 5 tm3 = sum . takeWhile(0) . flip map (iterate ((*)5) 5) . div Questions: Which one is the most elegant one generally speaking? Which one is most natural in Haskell? Is there more 'beauty' to possible? My personal choice is 'tm'. I like 'tm3' (a revised version of tm2) in terms of pointlessness and not having a 'where', but I think it's a bit contrived because of the 'flip'. Comments? Thanks @@i ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Style
On Aug 24, 2007, at 9:18 , Arie Groeneveld wrote: Hi, I defined several functions for calculating the number of trailing zero's of n! tm = sum . takeWhile(0) . iterate f . f where f = flip div 5 tm1 n = sum . takeWhile(0) . map (div n . (5^)) $ [1..] tm2 n = sum . takeWhile(0) . map (div n) $ iterate ((*)5) 5 tm3 = sum . takeWhile(0) . flip map (iterate ((*)5) 5) . div Questions: Which one is the most elegant one generally speaking? Which one is most natural in Haskell? Is there more 'beauty' to possible? My personal choice is 'tm'. I like 'tm3' (a revised version of tm2) in terms of pointlessness and not having a 'where', but I think it's a bit contrived because of the 'flip'. Comments? Here's a much more inefficient version, but it has the merit of being very easy to understand: tm_silly n = length $ takeWhile (=='0') $ reverse $ show $ product [1..n] /Björn ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Help using CGIT
On Aug 23, 2007, at 3:34 , Rich Neswold wrote: On 8/22/07, Ian Lynagh [EMAIL PROTECTED] wrote: On Wed, Aug 22, 2007 at 01:27:00PM -0500, Rich Neswold wrote: newtype App a = App (ReaderT Connection (CGIT IO) a) deriving (Monad, MonadIO, MonadReader Connection) Unfortunately, when another module tries to actually use the monad, I get warnings about No instance for (MonadCGI App). I tried making an instance: instance MonadCGI App where cgiAddHeader = ? cgiGet = ? You have three choices: 1: 2: 3: Provide a single instance for App that does the whole thing: instance MonadCGI App where cgiAddHeader n v = App $ lift $ cgiAddHeader n v cgiGet x = App $ lift $ cgiGet x This one you would obviously have to change if you added a StateT. Bingo! Method #3 works beautifully! I missed the using-lift-with- the-constructor permutation. Thanks for your help! I started writing a tutorial for Haskell web programming with the cgi package a while back, but haven't worked on it for a while, see http://www.haskell.org/haskellwiki/Practical_web_programming_in_Haskell I haven't added it to the list of tutorials yet, since it's still rather incomplete. The section on using CGIT is just a stub, perhaps you would like to contribute to it? See http://www.haskell.org/haskellwiki/ Practical_web_programming_in_Haskell#Extending_the_CGI_monad_with_monad_ transformers /Björn___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] latest cabal conflict?
when trying to build the latest cabal from darcs, I got [EMAIL PROTECTED]:~/src/cabinstall/cabal$ runghc Setup.lhs configure Distribution/Simple.hs:110:7: Could not find module `System.FilePath': it was found in multiple packages: filepath-1.0 FilePath-0.11 [EMAIL PROTECTED]:~/src/cabinstall/cabal$ sound like a conflict , i still have ghc 6.6, not 6.6.1. what should I do ? hide FilePath-0.11 in Distribution/Simple.hs imports ? ( and for all othe files? any way to just have FilePath out of the way via a Cabal statement? thks ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Style
Bjorn Bringert wrote: Here's a much more inefficient version, but it has the merit of being very easy to understand: tm_silly n = length $ takeWhile (=='0') $ reverse $ show $ product [1..n] You're rigth. I came up with that one too the first time. But for large value's of n it takes too much time. You may improve that (time) by using another product formula: *Main length $ takeWhile (=='0') $ reverse $ show $ foldl' (*) 1 [1..3] 7498 (0.96 secs, 790685000 bytes) *Main length $ takeWhile (=='0') $ reverse $ show $ product [1..3] 7498 (4.05 secs, 792259140 bytes) But: *Main tm 3 7498 (0.00 secs, 524924 bytes) Thanks @@i ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Style
On Fri, 24 Aug 2007, Arie Groeneveld wrote: I defined several functions for calculating the number of trailing zero's of n! tm = sum . takeWhile(0) . iterate f . f where f = flip div 5 This is very elegant! You could also inline 'f' tm4 = sum . takeWhile(0) . tail . iterate (flip div 5) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Haddock: documenting parameters of functional arguments
Henning Thielemann wrote:
I like to write documentation comments like
fix ::
( a {- ^ local argument -}
- a {- ^ local output -} )
- a {- ^ global output -}
but Haddock doesn't allow it. Or is there a trick to get it work?
Haddock only supports documenting the top-level arguments of a function
right now.
Cheers,
Simon
___
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Style
tm = sum . takeWhile(0) . iterate f . f where f = flip div 5 Quite nice. I like tm5 0 = 0 tm5 n = let q = div n 5 in q + tm5 q This version corresponds to what I'm think when parsing |tm|, so I wrote it down directly. Also possible tm6 = sum . unfoldr ( \ n - case div n 5 of 0 - mzero q - return (q,q) ) I tend to not use |iterate|, when it is known in advance, which prefix of the so constructed infinite list is used. /BR -- -- Mirko Rahn -- Tel +49-721 608 7504 -- --- http://liinwww.ira.uka.de/~rahn/ --- ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
RE: [Haskell-cafe] Re: Remember the future
| From the ghc manual: | | --- | 7.3.3. The recursive do-notation | ... | | It is unfortunate that the manual does not give the translation rules, or at | least the translation for the given example. Hmm. OK. I've improved the manual with a URL to the main paper http://citeseer.ist.psu.edu/erk02recursive.html which is highly readable. And I've given the translation for the example as you suggest Simon ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Style
Marc A. Ziegert [EMAIL PROTECTED] tm_parallelizable_v1 = \n - sum . takeWhile (0) $ map (div n) fives where fives = iterate (*5) 1 tm_improved_v1 n = sum . takeWhile (0) $ iterate (div `flip` 5) (div n 5) tm_fastestIMHO n = let m=div n 5 in if m5 then m else m+tm_fastestIMHO m Henning Thielemann [EMAIL PROTECTED] tm4 = sum . takeWhile(0) . tail . iterate (flip div 5) Bjorn Bringert [EMAIL PROTECTED] tm_silly n = length $ takeWhile (=='0') $ reverse $ show $ product [1..n] Arie Groeneveld [EMAIL PROTECTED] tm = sum . takeWhile(0) . iterate f . f where f = flip div 5 tm1 n = sum . takeWhile(0) . map (div n . (5^)) $ [1..] tm2 n = sum . takeWhile(0) . map (div n) $ iterate ((*)5) 5 tm3 = sum . takeWhile(0) . flip map (iterate ((*)5) 5) . div signature.asc Description: This is a digitally signed message part. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: [Haskell] Issue about use of WinHugs
Hi I'm new to WinHugs, what's wrong with isUpper of my WinHugs? Nothing. The book/tutorial you are going from is out of date. Before using the isUpper/isLower functions you first have to type :load Char: Hugs :load Char Hugs filter isUpper ABCDEfgh ABCDE The :load Char loads the Char module into scope, which provides the isUpper function. The haskell@ mailing list is mainly for announcements, so I've sent this email to haskell-cafe@ - which is the right place for questions like this. Thanks Neil ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] 2D game graphics library for Haskell?
I’m currently playing around with SOE to make some simple interactive math exercises for students. This worked fine, although I could have done this much faster using C# (which I know very well), but since I’m addicted to Haskell now, I used the latter language ;) Furthermore, I hope that one day, I will know enough Haskell to learn it to the students, because I feel that functional programming should not be given in the last bachelor or master years, since most software engineering students then know OO programming extremely well and have a horrible time with FP (I currently did not meet anyone in my sector of game development that liked FP, and many of those people had a masters degree and some were PhDs) Anyway, SOE is great for learning Haskell, but it lacks a couple of fundamental functions to make it really attractive, like: -Support for images -Support for rendering to an “offscreen graphics surface” and reading the pixels from that surface (for pixel-wise collision detection) -Support for detecting non-ASCII key presses (cursor keys, etc) -Support for joysticks Concurrent Clean seems to have a nice 2D game library and PLT/DrScheme also has nice support for basic 2D graphics, but somehow I feel Haskell is more mature and more elegant. So before digging into “advanced” APIs (like GTK itself, which I know nothing about, I’m a Win32 GDI/XNA/WPF expert), I should ask the question if something similar exists? It has to be as simple as SOE. Would it be possible to extend the GTK SOE with support for the features mentioned above? Is this insanely difficult for someone like me who knows a lot about Win32 but little Haskell? Thanks, Peter Verswyvelen No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.5.484 / Virus Database: 269.12.4/969 - Release Date: 23/08/2007 16:04 ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Style
Thanks for all the instructive replies and alternatives! Learned a bit more in terms of feeling about style and improvement of some of the functions: f.e. 'killing' the 'where' in my number one choice. Thanks @@i ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: newbie : multi-parameter type classes
Thomas Girod wrote: class (Eq n, Eq e) = Topo a n e where empty:: a empty does not allow to infer the types n and e nodes:: a - [n] also nodes leaves the type e undetermined http://www.haskell.org/ghc/docs/latest/html/users_guide/type-extensions.html#functional-dependencies Unfortunately http://www.cse.ogi.edu/~mpj/pubs/fundeps.html is broken. Christian ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: newbie : multi-parameter type classes
Thomas Girod wrote: Hi there. I'm trying to define a generic graph type here and don't understand on one error I get. Here I come. module Graph where class (Eq n, Eq e) = Topo a n e where empty:: a nodes:: a - [n] edges:: a - [e] This does not work without functional dependencies. Try: class (Eq n, Eq e) = Topo a n e | a - n e where HTH Christian P.S. Integer comes in via defaulting (of 0 or 1) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Style
Henning Thielemann wrote: tm4 = sum . takeWhile(0) . tail . iterate (flip div 5) FWIW: as a result of all this I learned to write this as: tm41 = sum . takeWhile(0) . tail . iterate (`div` 5) @@i ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: newbie : multi-parameter type classes
Unfortunately http://www.cse.ogi.edu/~mpj/pubs/fundeps.html is broken. http://web.cecs.pdx.edu/~mpj/pubs/fundeps.html ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] 2D game graphics library for Haskell?
Hi Peter, The OpenGL/GLUT bindings support all the things you would want, but it's a bit too much pain for first year students. For the last couple of years at the ANU (Australian National University, Canberra) we've been using a front end library that I wrote which is similar to SOE/HGL but with support for images, animation, alpha blending and some other things. I think the real trick is hiding enough of the OpenGL/GLUT internals to make it suitable for first year students, while at the same time exposing enough functionality so they don't feel constrained by what they can do with the library. Usually we think of the project we want the students to do, then supply most of the infrastructure via the library - leaving the students to fill in the 'fun' stuff. There is the added benefit that the OpenGL/GLUT bindings (and hence our library also) compiles out of the box on both Linux and Windows. We use linux machines at uni for the student labs, but students have been able to take their code home and get it running on their home Windows PC's without much difficulty. You can get our library (with examples) from my homepage at http://cs.anu.edu.au/people/Ben.Lippmeier/ I've also got a simple asteroids game which I wrote with an extended version of it. There is a playable version, but unfortunately it's on my home machine that is now packed in storage while I'm at MSR, Cambridge. I'm getting back to Canberra late October so if you're still interested I can dig it out and send you a copy then. Cheers, Ben. From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of peterv Sent: 24 August 2007 11:32 To: haskell-cafe@haskell.org Subject: [Haskell-cafe] 2D game graphics library for Haskell? I'm currently playing around with SOE to make some simple interactive math exercises for students. This worked fine, although I could have done this much faster using C# (which I know very well), but since I'm addicted to Haskell now, I used the latter language ;) Furthermore, I hope that one day, I will know enough Haskell to learn it to the students, because I feel that functional programming should not be given in the last bachelor or master years, since most software engineering students then know OO programming extremely well and have a horrible time with FP (I currently did not meet anyone in my sector of game development that liked FP, and many of those people had a masters degree and some were PhDs) Anyway, SOE is great for learning Haskell, but it lacks a couple of fundamental functions to make it really attractive, like: - Support for images - Support for rendering to an offscreen graphics surface and reading the pixels from that surface (for pixel-wise collision detection) - Support for detecting non-ASCII key presses (cursor keys, etc) - Support for joysticks Concurrent Clean seems to have a nice 2D game library and PLT/DrScheme also has nice support for basic 2D graphics, but somehow I feel Haskell is more mature and more elegant. So before digging into advanced APIs (like GTK itself, which I know nothing about, I'm a Win32 GDI/XNA/WPF expert), I should ask the question if something similar exists? It has to be as simple as SOE. Would it be possible to extend the GTK SOE with support for the features mentioned above? Is this insanely difficult for someone like me who knows a lot about Win32 but little Haskell? Thanks, Peter Verswyvelen No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.5.484 / Virus Database: 269.12.4/969 - Release Date: 23/08/2007 16:04 ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Style
Arie Groeneveld wrote: tm = sum . takeWhile(0) . iterate f . f where f = flip div 5 Which one is the most elegant one generally speaking? I like that tm only uses div. My personal choice is 'tm'. I like 'tm3' (a revised version of tm2) in terms of pointlessness and not having a 'where', but I think it's a bit contrived because of the 'flip'. You can make tm whereless by noticing that you use because you use the function twice in iterate f . f, which is because you don't want the initial value that iterate gives. You can instead use tail on iterate's result, and use a section to avoid flip: tm = sum . takeWhile (0) . tail . iterate (`div` 5) (Hope that works, can't test now...) All the best Christian Sievers ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] IO inside CGI
-BEGIN PGP SIGNED MESSAGE- Hash: RIPEMD160 I'm toying around with web programming in Haskell. I'm trying to write a script which GETs an id and returns a couple of random numbers. Something like this: cgiMain :: CGI CGIResult cgiMain = do inp - getInput id let gen = parse inp output $ take 10 (randoms gen) parse :: Maybe String- StdGen parse (Just x) = read x parse Nothing = undefined Now I'd like to get a new StdGen, in case no id was supplied to the script. cgiMain :: CGI CGIResult cgiMain = do inp - getInput id gen - parse inp output $ take 10 (randoms gen) parse :: Maybe String- IO StdGen parse (Just x) = return $ read x parse Nothing = getStdGen Obviously this doesn't work because I'm trying to do IO inside CGI (right?). Is there some incantation I can perform to make this possible? Like gen - arcaneMagic parse inp As you probably have noticed I don't know very much about monads, all I did until now was reading or writing some files. Thanks in advance -BEGIN PGP SIGNATURE- Version: GnuPG v1.4.7 (MingW32) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFGzudU11V8mqIQMRsRA33RAJ9buZDHgz/eXi8Jw9OBwbTErDccRgCfbGrr 1WXiGHmxlTBe01E409yJyv8= =XSDj -END PGP SIGNATURE- ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: IO inside CGI
Adrian Neumann wrote: Now I'd like to get a new StdGen, in case no id was supplied to the script. parse :: Maybe String- IO StdGen parse (Just x) = return $ read x parse Nothing = getStdGen Obviously this doesn't work because I'm trying to do IO inside CGI (right?). Is there some incantation I can perform to make this possible? Abracadabra, the incantation is liftIO :: IO a - CGI a i.e. parse :: Maybe String- CGI StdGen parse (Just x) = return $ read x parse Nothing = liftIO getStdGen Regards, apfelmus ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] IO inside CGI
2007/8/24, Adrian Neumann [EMAIL PROTECTED]: Obviously this doesn't work because I'm trying to do IO inside CGI (right?). Is there some incantation I can perform to make this possible? Like gen - arcaneMagic parse inp As doing IO in the CGI Monad is a current need, it's an instance of MonadIO and as such provide liftIO, so your arcaneMagic is called liftIO : cgiMain :: CGI CGIResult cgiMain = do inp - getInput id gen - liftIO $ parse inp output $ take 10 (randoms gen) parse :: Maybe String- IO StdGen parse (Just x) = return $ read x parse Nothing = getStdGen -- Jedaï ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] RE: Re: Remember the future
Simon Peyton-Jones wrote: | It is unfortunate that the [ghc] manual does not give the translation rules, or at | least the translation for the given example. Hmm. OK. I've improved the manual with a URL to the main paper http://citeseer.ist.psu.edu/erk02recursive.html which is highly readable. And I've given the translation for the example as you suggest Cool, thanks. BTW, the Haskell' wiki says its adoption status is 'probably no' which I find unfortunate. IMHO recursive do is a /very/ useful and practical feature and the cons listed on http://hackage.haskell.org/trac/haskell-prime/wiki/RecursiveDo don't weigh enough against that. Ok, just my (relatively uninformed) 2 cents. Cheers Ben ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Remember the future
Benjamin Franksen wrote:
Simon Peyton-Jones wrote:
| It is unfortunate that the [ghc] manual does not give the translation
rules, or at
| least the translation for the given example.
Hmm. OK. I've improved the manual with a URL to the main paper
http://citeseer.ist.psu.edu/erk02recursive.html
which is highly readable. And I've given the translation for the example
as you suggest
Cool, thanks.
BTW, the Haskell' wiki says its adoption status is 'probably no' which I
find unfortunate. IMHO recursive do is a /very/ useful and practical
feature and the cons listed on
http://hackage.haskell.org/trac/haskell-prime/wiki/RecursiveDo don't weigh
enough against that. Ok, just my (relatively uninformed) 2 cents.
Cheers
Ben
I will assume that the current compilers will keep the current mdo desugaring.
It is incredibly valuable, and I use it in two different monad stacks in the
regex-tdfa package I released.
It has been an implemented extension for quite several version of GHC, and with
the separate mdo keyword it does not interfere with other code.
Why have a lazy language with added monad do sugaring support and balk at
adding such a well tested and deployed way to use sugar for combining laziness
and monads? Toy there g is an identity monadic version of f and h shows the
kind of logic I tend to intersperse in an mdo block:
module Main where
import Control.Monad.Fix
import Control.Monad.Identity
import Control.Monad.Writer
f x = do
let a = x*b
b = x+1
return a
test_f = runIdentity (f 2) -- 6
g x = mdo
a - return (x*b)
b - return (x+1)
return a
test_g = runIdentity (g 2) -- 6
h x = mdo
a - return (x*b)
if even b then tell [('a',a)] else return ()
b - return (x+1)
tell [('b',b)]
return a
test_h1 = (runWriter (h 1)) -- (2,[('a',2),('b',2)])
test_h2 = (runWriter (h 2)) -- (6,[('b',3)])
--
Chris
___
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Graph reduction [Was: Where is StackOverflow on the Wiki?]
Shiqi Cao wrote: Check out this http://www.cas.mcmaster.ca/~kahl/HOPS/ http://www.cas.mcmaster.ca/%7Ekahl/HOPS/ Heh. I was thinking about trying to build something *exactly like* this... OOC, how the heck did they make it work through a document interface? Surely that's impossible? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Haskellnet could not find network-any dependency.
Hi, I am trying to install Haskellnet. But the configuration breaks on dependency of network-any in GHC 6.6. I thought network-any was part of Hierarchical libraries? If not where do I get it? Edaward. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Help using CGIT
On 8/24/07, Bjorn Bringert [EMAIL PROTECTED] wrote: On Aug 23, 2007, at 3:34 , Rich Neswold wrote: Bingo! Method #3 works beautifully! I missed the using-lift-with- the-constructor permutation. Thanks for your help! I started writing a tutorial for Haskell web programming with the cgi package a while back, but haven't worked on it for a while, see http://www.haskell.org/haskellwiki/Practical_web_programming_in_Haskell I haven't added it to the list of tutorials yet, since it's still rather incomplete. The section on using CGIT is just a stub, perhaps you would like to contribute to it? See http://www.haskell.org/haskellwiki/ Practical_web_programming_in_Haskell#Extending_the_CGI_monad_with_monad_ transformers Done. As I learn more about using CGIT, I'll try to remember to add more content. Any suggestions to improve it are welcome! -- Rich JID: [EMAIL PROTECTED] AIM: rnezzy ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Style
whops... i did check it, but that was a copypaste mistake. buggy: tm_parallelizable_v1 = \n - sum . takeWhile (0) $ map (div n) fives where fives = iterate (*5) 1 should be: tm_parallelizable_v1 = \n - sum . takeWhile (0) $ map (div n) fives where fives = iterate (*5) 5 - marc Am Freitag, 24. August 2007 schrieben Sie: Hi Marc First off, thanks for your reply. tm_parallelizable_v1 = \n - sum . takeWhile (0) $ map (div n) fives where fives = iterate (*5) 1 Did you check this one? IMHO I think it's producing the 'wrong' answer. *Main tm_parallelizable_v1 100 124 (0.00 secs, 0 bytes) *Main tm 100 24 (0.00 secs, 0 bytes) If comparing the result to the other variants is accepted as a sort of proof. ;-) But calculating the number of trailing zero's of n! is a matter of counting powers of five in the factorized n!: f.e.: 10! = 1 2 3 2^2 5 2*3 7 2^3 3^2 2*5 -- 5^2 -- picking up enough powers of 2 -- (2*5)^2 = 100 So you will have to correct your 'fives' to f.e. fives = tail $ iterate (*5) 1 Regards @@i signature.asc Description: This is a digitally signed message part. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
