- Hugs-Users - Haskell.org

School assignment help
by Urmastaag 24 Oct '07

24 Oct '07

Hello! Can anybody point me to a right way here? I have those exercises in haskell that i cannot do, because haskell is so much different from other languages that i use. I have read so much from different manuals but i do not understand haskell enough yet. First exercise: I must find a shorter list. Here's how i did that, but my teacher said that it is unefficient way to do it. getShorter :: [a] -> [a] -> [a] getShorter xs ys | length xs <= length ys = xs | otherwise = ys How do i do it effective, so that i only check as many elements from lists as many are in the shortest list? Second exercise: Second exercise also need an effective answer: I have to remove any occurances of certain number from list and give the number of how many times that number was removed. Unefficient version: remCount :: Int -> [Int] -> (Int,[Int]) remCount n xs = (length xs - length ys, ys) where ys = [ x | x <- xs, x /= n] Exercise three: moneyBack :: Int -> [(Int,Int)] I must print out all pairs of bank notes and (bank notes, how many) which salesman would give me back when he/she has to give me like 456 back. moneyBack 0 ==> [] moneyBack 10 ==> [(10,1)] moneyBack 123 ==> [(100,1),(10,2),(2,1),(1,1)] moneyBack 5326 ==> [(500,10),(100,3),(25,1),(1,1)] If anybody could point me in a right direction that would be great. Haskell seems very cool because the code is usually really short, but i just need a start. I need more examples than i can find from google (maybe i'm not using the right keywords). Thanks. -- View this message in context: http://www.nabble.com/School-assignment-help-tf4685176.html#a13388655 Sent from the Haskell - Hugs-Users mailing list archive at Nabble.com.

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Graphics Library for Hugs
by ferronrsmith 08 Oct '07

08 Oct '07

I want to create some GUI in hugs (I know GHC works) for class, but I just can't seem to find any for hugs help??? is there any available ??? -- View this message in context: http://www.nabble.com/Graphics-Library-for-Hugs-tf4588765.html#a13098425 Sent from the Haskell - Hugs-Users mailing list archive at Nabble.com.

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A New Notation for Arrows
by bft 21 Sep '07

21 Sep '07

On Thu, May 31, 2007 at 02:55:49PM +0100, bft wrote: >* Is there any version of Haskell (Hugs or Ghc) which includes the new *>* notation of arrows introduced by Ross Paterson ? Instead, where can I get *>* it ? The Control.Arrow.hs file did not include the new notation of *>* arrows. * *Ross Paterson wrote :* > It's supported by GHC 6.2 and later, with the -farrows option >(see the GHC User's Guide). To use arrow notation with Hugs or > any other Haskell implementation, you need the arrows preprocessor >(http://www.haskell.org/arrows/download.html) Thank you for your prompt answer. I tried to download the x86/Linux Binary Release arrowp-0.5-linux-i386.tgz at http://www.haskell.org/arrows/download.html ; but it failed with this message : "Not Found The requested URL /arrows/arrowp-0.5-linux-i386.tgz was not found on this server." I tried the Unix Source Release: arrowp-0.5-src.tgz, but I failed when building it on my Linux Fedora Core 6 system. I have a ghc-6.6.1 Haskell compiler and the Hugs98 (march 2005 version) Haskell interpreter. Thanks again for your help. Bernard Fotsing Talla

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Re: [Hugs-users] Request for Haskell Help
by ferronrsmith 19 Sep '07

19 Sep '07

We are all here to help, but you have to post your problems so that others can help.. My site is a very good resource for learning haskell: http://haskell.kwikphp.com/haskell/index.php Haskell for Beginners -- View this message in context: http://www.nabble.com/Request-for-Haskell-Help-tf3659849.html#a12787216 Sent from the Haskell - Hugs-Users mailing list archive at Nabble.com.

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WinHugs extremely basic newbie question
by Risto Rangel Kuoppa 06 Sep '07

06 Sep '07

Hello everyone, I am having troubles to start using WinHugs. I downloaded it, installed, and run it. Yet I am unable to run something else than just evaluating expressions. For example, I am trying to define my first data type with: Hugs> data Tipo = Cruz | Circulo deriving Eq But all I get is: ERROR - Syntax error in expression (unexpected keyword "data") Hugs> I think that I must load some module or library but when I make: Hugs> :load "C:\\Program Files\\WinHugs\\packages\\hugsbase\\Hugs\\Prelude.hs" I get: ERROR file:.\Prelude.hs - Module "Hugs.Prelude" already loaded Hugs.Prelude> And I cannot find any Data.hs (Does it actually exist?) anywhere. Could someone help me with this please? I have already spent several hours trying to figure it out. All I want is to start testing the tutorials and learn Haskell but I am missing something to run them with WinHugs. Thanks in advance, Risto

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library directory
by Ian Zimmerman 10 Jun '07

10 Jun '07

Is it possible to somehow determine mechanically what the standard library directory of a running Hugs interpreter is? The output of :set gives the load path, but that hides the library directory as {Hugs}. Some other (unnamed, grin) tools provide similar information in their --version output, or have a special option that outputs only this. Thanks. -- This line is completely ham.

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Yaham - Yet Another HAskell Mode for GNU Emacs
by Ian Zimmerman 10 Jun '07

10 Jun '07

Quoting the README file: This is Yaham, Yet Another HAskell Mode for GNU Emacs. It has a different focus than the Moss haskell-mode that's normally used nowadays. Yaham strives, first and foremost, to integrate well with the rest of Emacs and respect the Emacs ecosystem. This is because I still use languages different from Haskell --- python, shell, Makefiles, even C ...) and see no end to this predicament. To my knowledge, Yaham completely and correctly handles all of Haskell's unusual lexical syntax - both line and nested comments, overloading of single quote and backslash, strings including gaps. There should be no runaway string or comment highlighting or broken cursor movement across these elements. If you find a broken case, please report it to the address below including the relevant piece of Haskell. Things that are still missing but are high priority to add: * specialization for GHC (one for Hugs is included) * texinfo documentation (for now, please explore the menus and keybindings) * installation script (perhaps a makefile) Things that are very low priority (i.e. probably won't be added): * Bird style literate source handling * XEmacs compatibility kludges To use or try it, * download http://primate.net/~itz/yaham/yaham.tar.gz * unpack * read the LICENSE (yes, please do) * copy *.el files to your local Elisp directory * optionally, byte-compile * add the following to your Emacs initialization (load-library "yaham-autoloads") (add-to-list 'auto-mode-alist '("\\.hs\\'" . yaham-mode)) ;; or if you have Hugs, you can do this: ;; (add-to-list 'auto-mode-alist '("\\.hs\\'" . yaham-hugs-mode)) Send all problem reports and patches to me (Ian Zimmerman) at yaham(a)madbat.mine.nu P.S. If you want to hack on it, let me know and I'll consider giving you access to the Subversion repo. Peace, Ian. -- This line is completely ham.

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execution trace?
by Joe Buehler 08 Jun '07

08 Jun '07

Is there any way to have hugs dump a trace during execution of a program? I would like to compare execution of a script on two machines, one working properly, one not, and see where they diverge. Joe Buehler

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strange socket I/O problem under HPUX 11.0
by Joe Buehler 08 Jun '07

08 Jun '07

I ported Hugs to a number of UNIX variants but am running into a strange problem under HPUX 11.0. I wrote a trivial server program that reads a line from a socket and writes a message back to the client. This works fine, except under HPUX, where it does write the message to the client, but before it writes the message it writes back the line that was read from the client! Any ideas on this? Does Hugs use straight stdio or does it do something funny like reaching into the internals of the stdio data structures? Joe Buehler

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A New Notation for Arrows
by bft 31 May '07

31 May '07

Hello Is there any version of Haskell (Hugs or Ghc) which includes the new notation of arrows introduced by Ross Paterson ? Instead, where can I get it ? The Control.Arrow.hs file did not include the new notation of arrows. Thanks for your help. BFT

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