Questions concerning hierarchical module system
Hi, I have some questions regarding the hierarchical module system now implemented in Hugs as well as in GHC. Currently it is possible to have a module A1.A2. ... .Am and a module A1.A2. ... .Am. ... .An (n > m) at the same time. The first one's source code would be in file /A1/A2/ ... /Am.hs and the second one's in file /A1/A2/ ... /Am/ ... /An.hs. So there would be both a Am.hs file and a Am directory in the same directory. A1.A2. ... .Am would have two meanings: a module and a "module container". Hugs and GHC doesn't seem to have problems with this. But I want to know if I can rely on this behaviour still beeing present in future implementations and if this kind of module organisation is maybe considered bad practice. Wolfgang ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
Haskell Web Publisher --- help wanted
Hello Haskell freaks, I'm developing some software which I call the "Haskell Web Publisher". This software shall allow the implementation of websites in Haskell and will consist mainly of Haskell modules providing the necessary types and variables. By using HWP, website implementors shall be able to write clear and problem-oriented website implementations. In addition, many errors (e.g. "broken links") shall be prevented by compiler checks. This shall be achieved by using Haskell's type system appropriately. I have written some kind of paper about the basic ideas which can, at the moment, be downloaded by using the following URI: http://www.wolfgang.jeltsch.net/ convenient-website-implementation-with-haskell.pdf I decided to exclude all the code from HWP which may also be useful for other software This code will form a separate library called Seaweed. During the last 2 1/2 years I worked on the described kind of software. Last year I decided to revise some of the code and to rewrite the rest of it. In conjunction with this I made the split into Seaweed and HWP and began hosting these projects on Sourceforge (now Sourceforge.net). The respective URI are these: http://sourceforge.net/projects/seaweed/ http://sourceforge.net/projects/hwp/ Because I didn't have the time, I didn't rewrite the existing HWP stuff and didn't write what is missing of HWP until now. I only worked on the Seaweed part. Some of the resulting code is already in the CVS repository, and some code is on my harddisk and will, hopefully, be checked in during April/May. If somebody should be interested, I can also send him/her the code from before the revision/rewrite phase which covers some of the more interesting stuff of HWP, namely code for realising the compiler checks mentioned above. Now let me come to the aim of this e-mail. I'm looking for people who are interested in helping me realising HWP and Seaweed. Because I develop these things only in my free time, finishing them is far away if it's only me who is working on them. So if someone of you is interested in taking part in the development process, please, please write me! Thank you in advance! Okay, I will finish now and I hope for reply. Ciao, Wolfgang ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
Re: data structure question
perhaps you can modify 'gperf' (the gnu perfect hash function generator) to output haskell rather than c. i actually looked into this before, it should not be too tough as gperf always generates a generic polynomial and just the coefficients are different for diffirente input, it would be pretty easy to awk those out and reimplement the generic function in haskell. alternativly you could roll your own.. some useful information is here http://burtleburtle.net/bob/hash/perfect.html and around. John On Wed, Apr 17, 2002 at 11:11:50AM -0700, Hal Daume III wrote: > i need an associative data structure (like finitemap) which will map data > elements to Doubles. i don't need to be able to remove elements and don't > even need to insert elements once i've built the structure; all i really > care about is fast lookup. i have reasonable instances of Eq and Ord and > probably any other reasonable comparitive metric you could think > of. moreover, when i'm creating the data structure, i *know* the > (approximate) relative frequency of each element. that is, i know that > on average i will need to get the Double corresponding to element 'a' ten > times more frequently than the Double corresponding to element 'b'. > > does anyone have any suggestions for data structures to solve such a > problem. i'm currently using FiniteMap, but would like something faster > (btw, there are a LOT of these elements -- around 1million or so). > > - Hal > > -- > Hal Daume III > > "Computer science is no more about computers| [EMAIL PROTECTED] > than astronomy is about telescopes." -Dijkstra | www.isi.edu/~hdaume > > ___ > Haskell mailing list > [EMAIL PROTECTED] > http://www.haskell.org/mailman/listinfo/haskell > -- --- John Meacham - California Institute of Technology, Alum. - [EMAIL PROTECTED] --- ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
Flocasa: 2nd Call for Paper
[ Our apologies for multiple copies. ] == 1st International Workshop on Foundations of Coordination Languages and Software Architectures (Foclasa 2002) August 24, 2002, Brno, Czech Republic Workshop affiliated to CONCUR'2002, 20 - 23 August 2002. http://www.info.fundp.ac.be/~jmj/Workshops/Concur2002/Foclasa.html == SCOPE AND TOPICS Modern information systems rely more and more on combining concurrent, distributed, mobile and heterogenous components. This move from old systems, typically conceived in isolation, induces the need for new languages and software architectures. In particular, coordination languages have been proposed to cleanly separate computational aspects and communication. On the other hand, software architects face the problem of specifying and reasoning on non-functional requirements. All these issues are widely perceived as fundamental to improve software productivity, enhance maintainability, advocate modularity, promote reusability, and lead to systems more tractable and more amenable to verification and global analysis. The aim of the workshop is to bring together researchers working on the foundations of component-based computing, coordination, and software architectures. Topics of interest include (but are not limited to): o Theoretical models for coordination (component composition, concurrency, dynamic aspects of coordination, semantics, expressiveness); o Specification, refinement, and analysis of software archi- tectures (patterns and styles, verification of functional and non-functional properties); o Coordination, architectural, and interface definition languages (implementation, interoperability, heterogeneity); o Agent-oriented languages (formal models for interacting agents); o Dynamic software architectures (mobile agents, configuration, reconfiguration); o Modeling of information systems (groupware, internet and the web, workflow management, CSCW and multimedia applications) o Coordination patterns (mobile computing, internet computing); o Tools and environments for the development of coordinated applications SUBMISSION GUIDELINES Papers describing original work are solicited as contributions to Foclasa. Submitted papers should be limited to 6 000 words, preferrably formatted according to the Fundamenta Informaticae style (available at http://fi.mimuw.edu.pl/submissions.html). They should be emailed as PostScript (PS) or Portable Document Format (PDF) files to [EMAIL PROTECTED] PROCEEDINGS The proceedings will be published as a technical report of the Institute of Informatics at the University of Namur, and will be available at the workshop. PUBLICATION Selected papers will be published in a special issue of the Funda- menta Informaticae journal, with February 2003 as expected publi- cation time. IMPORTANT DATES: o May 25, 2002:Submission deadline. o June 30, 2002: Notification of acceptance. o August 1, 2002: Final version. o August 24, 2002: Meeting Date. LOCATION The workshop will be held in Brno in August 2002. It is a satellite workshop of CONCUR 2002. For venue and registration see the CONCUR web page at http://www.fi.muni.cz/concur2002/ WORKSHOP ORGANIZERS o Antonio Brogi (University of Pisa, Italy) o Jean-Marie Jacquet (University of Namur, Belgium) PROGRAMME COMITTEE: o Antonio Brogi (University of Pisa, Italy) - Co-chair o Rocco De Nicola (University of Firenze, Italy) o Jos Luiz Fiadeiro (ATX Software and Univ. of Lisbon, Portugal) o Roberto Gorrieri (Univerity of Bologna, Italy) o Paola Inverardi (Univerity L'Aquila, Italy) o Jean-Marie Jacquet (University of Namur, Belgium) - Co-chair o Joost Kok (University of Leiden, The Netherlands) o Antonio Porto (New University of Lisbon, Portugal) ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
data structure question
i need an associative data structure (like finitemap) which will map data elements to Doubles. i don't need to be able to remove elements and don't even need to insert elements once i've built the structure; all i really care about is fast lookup. i have reasonable instances of Eq and Ord and probably any other reasonable comparitive metric you could think of. moreover, when i'm creating the data structure, i *know* the (approximate) relative frequency of each element. that is, i know that on average i will need to get the Double corresponding to element 'a' ten times more frequently than the Double corresponding to element 'b'. does anyone have any suggestions for data structures to solve such a problem. i'm currently using FiniteMap, but would like something faster (btw, there are a LOT of these elements -- around 1million or so). - Hal -- Hal Daume III "Computer science is no more about computers| [EMAIL PROTECTED] than astronomy is about telescopes." -Dijkstra | www.isi.edu/~hdaume ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
Re: Bug?
On Tuesday 16 April 2002 07:15 pm, Jorge Adriano wrote:
> [1] Bug1?
>
> This declaration:
> > A = (,) Int Int
>
> is accepted by ghci. Is this behaveour correct,
> 1. It kind of shadows (,) is defined in PrelTup meaning that you can no
> longer use (,) prefix to refer to tuples - like (,) 1 2.
> 2. Seems to me like (,) is not correct syntax for a consym as defined in
> the H98 Report so we shouldn't be able to redefine it.
> ...
I found that ghci (I'm using version 5.02.2) will also allow you to reuse []
as a constructor, as in:
> data Foo a = [] a deriving Show
For some reason, though, this has the side effect of causing a segmentation
fault whenever I type in a literal list like [1,2,3]. Here are some other
weird things you can try:
> data [] a = [] Int deriving Show
--ghci complains about duplicate instances
> data [] = [] Int deriving Show
Test> [] 6543
[] 6543
Test> :i []
-- PrelBase.[] is a data constructor
PrelBase.[] :: Int*** Exception: Prelude.head: empty list
>data (,) a b = (,) b a
Test> ('a',72::Int)
('a',72)
Test> (,) 'a' (72::Int)
(97,'H')
>data (,) a b = (,) b a
>typecast :: a -> b
>typecast x = fst ((,) x undefined)
Evidently, when you redefine the datatypes [] or (,), you can change the
internal representation of those types, without affecting their class
instances or other functions that may have depended on the original
representation. Obviously this does not preserve type safety.
I see two possible remedies: (1) Simply disallow [] and (,) as user-defined
types, or (2) Allow users to define their own versions of [] and (,), but use
qualified names to distinguish them from the originals.
- Brian Huffman
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Re: Bug?
On Wednesday 17 April 2002 03:15, Jorge Adriano wrote: > [1] Bug1? > This declaration: > > A = (,) Int Int Opsss cut and paste problems :) > data A = (,) Int Int > is accepted by ghci. Is this behaveour correct, This is what I meant. Anyway in Bug 2 I used the 'correct' declaration > [2] Bug2? > - Step 1 > Load this in ghci, > --- > module Test where > data C = C ((,) Int Int) > > data A = (,) !Int !Int -- <--- There it is J.A. ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
Re: Coding Problems!! Please help
I am currently working on an assignment with requires us to write in Haskell. I am having trouble with "pipeline". The required textbook called, "The Craft of Functional Programming" 2nd Edition. There is a pipeline example, which I find it useful in my assignment, but for some reason, there may be a typo in the pipeline syntax, which is ">.>". Coz it doesn't compile. Your problem is that that book defines and uses a non-standard composition operator. The standard Haskell function composition is written just ".", defined by (f . g) x = f (g x) Notice that in f . g, it is *g* which is applied first to the argument, and f which is applied to the result of that. That is, composition is "backwards" in some sense. Here's an example: sqrt . abs takes the absolute value of its argument first, and then the square root of that, not the absolute value of the square root (which would fail for negative arguments). Many people (including mathematicians) prefer to write the arguments of compose in the other order, so that the first function to be applied is the first one you write. To make that possible, Simon Thompson defines (f >.> g) x = g (f x) So now you would write the example above as abs >.> sqrt You take the absolute value first, so you write it first. Regardless of which you prefer, the important thing to understand is that >.> IS NOT PART OF THE HASKELL STANDARD. So if you want to use it, you have to include the definition above in your own program. John Hughes ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
Re: Coding Problems!! Please help
ons 2002-04-17 klockan 09.25 skrev Jack Tsai: > I am currently working on an assignment with requires us to write in > Haskell. I am having trouble with "pipeline". The required textbook called, > "The Craft of Functional Programming" 2nd Edition. There is a pipeline > example, which I find it useful in my assignment, but for some reason, there > may be a typo in the pipeline syntax, which is ">.>". Coz it doesn't compile > @_@ Well, normally I would tell you to ask your teacher for advice, but it seems you have done a lot of work yourself here, and only got stuck on the strange >.> operator. One of the things about this book which I don't like is that Thompson introduces a lot of non-standard functions. You can try to make the following definition in your file: (>.>) = flip (.) Regards, Martin -- Martin Norbäck [EMAIL PROTECTED] Kapplandsgatan 40 +46 (0)708 26 33 60 S-414 78 GÖTEBORG http://www.dtek.chalmers.se/~d95mback/ SWEDEN OpenPGP ID: 3FA8580B signature.asc Description: PGP signature
Coding Problems!! Please help
Dear staff, I am currently working on an assignment with requires us to write in Haskell. I am having trouble with "pipeline". The required textbook called, "The Craft of Functional Programming" 2nd Edition. There is a pipeline example, which I find it useful in my assignment, but for some reason, there may be a typo in the pipeline syntax, which is ">.>". Coz it doesn't compile @_@ I have attached a file of the example, I found from the book. There is a website where I could download the entire book. It's got the same stuff as in my textbook. Please help me, coz i've tried even Unix's pipeline syntax which is obviously wrong... I'm not desperate, please reply, thank you very much. Sincerely, Jack This is the output of the compilor... /*/ Haskell 98 mode: Restart with command line option -98 to enable Reading file "C:\PROGRAM FILES\HUGS98\lib\Prelude.hs": Parsing Dependency analysis Type checking.. Compiling.. Reading file "E:\433\CHAPTE~1.LHS": Parsing Dependency analysis ERROR "E:\433\CHAPTE~1.LHS" (line 22): Undefined variable ">.>" Prelude> /**/ _ Send and receive Hotmail on your mobile device: http://mobile.msn.com ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
Coding Problems!! Please help
Dear staff, I am currently working on an assignment with requires us to write in Haskell. I am having trouble with "pipeline". The required textbook called, "The Craft of Functional Programming" 2nd Edition. There is a pipeline example, which I find it useful in my assignment, but for some reason, there may be a typo in the pipeline syntax, which is ">.>". Coz it doesn't compile @_@ I have attached a file of the example, I found from the book. There is a website where I could download the entire book. It's got the same stuff as in my textbook. Please help me, coz i've tried even Unix's pipeline syntax which is obviously wrong... I'm not desperate, please reply, thank you very much. Sincerely, Jack This is the output of the compilor... /*/ Haskell 98 mode: Restart with command line option -98 to enable Reading file "C:\PROGRAM FILES\HUGS98\lib\Prelude.hs": Parsing Dependency analysis Type checking.. Compiling.. Reading file "E:\433\CHAPTE~1.LHS": Parsing Dependency analysis ERROR "E:\433\CHAPTE~1.LHS" (line 22): Undefined variable ">.>" Prelude> /**/ _ Chat with friends online, try MSN Messenger: http://messenger.msn.com Haskell: The Craft of Functional Programming Simon Thompson (c) Addison-Wesley, 1999. Chapter 10 Example: creating an index ^^ The basic type symonyms > type Doc = String > type Line = String > type Word = String The type of the top-level function The top-level definition > makeIndex :: Doc -> [ ([Int],Word) ] > makeIndex > = lines >.> -- Doc-> [Line] > numLines>.> -- [Line] -> [(Int,Line)] > allNumWords >.> -- [(Int,Line)] -> [(Int,Word)] > sortLs >.> -- [(Int,Word)] -> [(Int,Word)] > makeLists >.> -- [(Int,Word)] -> [([Int],Word)] > amalgamate >.> -- [([Int],Word)] -> [([Int],Word)] > shorten -- [([Int],Word)] -> [([Int],Word)] Implementing the component functions Attach a number to each line. > numLines :: [Line] -> [ ( Int , Line ) ] > numLines linels > = zip [1 .. length linels] linels Associate each word with a line number > numWords :: ( Int , Line ) -> [ ( Int , Word ) ] > numWords (number , line) > = [ (number , word) | word <- Chapter7.splitWords line ] The definition uses splitWords from Chapter 7, modified to use a different version of whitespace. For this to take effect, need to make the modification in the Chapter7.lhs file. > whitespace :: String > whitespace = " \n\t;:.,\'\"!?()-" Apply numWords to each integer,line pair. > allNumWords :: [ ( Int , Line ) ] -> [ ( Int , Word ) ] > allNumWords = concat . map numWords The list must next be sorted by word order, and lists of lines on which a word appears be built. The ordering relation on pairs of numbers and words is given by > orderPair :: ( Int , Word ) -> ( Int , Word ) -> Bool > orderPair ( n1 , w1 ) ( n2 , w2 ) > = w1 < w2 || ( w1 == w2 && n1 < n2 ) Sorting the list using the orderPair ordering on pairs. > sortLs :: [ ( Int , Word ) ] -> [ ( Int , Word ) ] > sortLs [] = [] > sortLs (p:ps) > = sortLs smaller ++ [p] ++ sortLs larger > where > smaller = [ q | q<-ps , orderPair q p ] > larger = [ q | q<-ps , orderPair p q ] The entries for the same word need to be accumulated together. First each entry is converted to having a list of line numbers associated with it, thus > makeLists :: [ (Int,Word) ] -> [ ([Int],Word) ] > makeLists > = map mklis > where > mklis ( n , st ) = ( [n] , st ) After this, the lists associated with the same words are amalgamated. > amalgamate :: [ ([Int],Word) ] -> [ ([Int],Word) ] > amalgamate [] = [] > amalgamate [p] = [p] > amalgamate ((l1,w1):(l2,w2):rest) > | w1 /= w2= (l1,w1) : amalgamate ((l2,w2):rest) > | otherwise = amalgamate ((l1++l2,w1):rest) Remove all the short words. > shorten :: [([Int],Word)] -> [([Int],Word)] > shorten > = filter sizer > where > sizer (nl,wd) = length wd > 3 Verification and general functions ^^ All the functions used in this section have been defined earlier.
