Re: [Haskell-cafe] Explaining monads

On 8/10/07, Ronald Guida <[EMAIL PROTECTED]> wrote: > > Kim-Ee Yeoh wrote: > > Monads are undoubtedly more pervasive, and that could be because there > > aren't as many arrow and comonad tutorials, atomic ones or otherwise. > > Moreover, Comonad isn't even in the standard libraries (Hoogle return

Re: [Haskell-cafe] Explaining monads

ronguida: > > > Monads are undoubtedly more pervasive, and that could be because there > > aren't as many arrow and comonad tutorials, atomic ones or otherwise. > > Moreover, Comonad isn't even in the standard libraries (Hoogle returns > no results for it). > > When I searched for tutorials on m

[Haskell-cafe] zip3, zip4 ... -> zipn?

Is it possible to write a function like this: zipn n list_1 list_2 list_3 ... list_n which implements zip3 for n=3, zip4 for n=4 etc.? Looks like variable number of arguments are possible, like printf shows, so a general zipn should be possible, too. If it is possible, why there are functions lik

Re: [Haskell-cafe] Explaining monads

Ronald Guida wrote: > > Here's my interpretation of the table: > > -- > Structure | Subject | Action| Verb | Result > +--+++-- > function| a | a-

Re: [Haskell-cafe] Haskell vs GC'd imperative languages, threading, parallelizeability (is that a word? :-D )

Spencer Janssen wrote: On Friday 10 August 2007 12:37:31 Andrew Coppin wrote: Stefan O'Rear wrote: Bool is 32 bits, but Don is using UArray. UArray is not parametric in the element type. Would be nice if it *could* somehow be parametric... but I have absolutely no idea how you'

Re: [Haskell-cafe] zip3, zip4 ... -> zipn?

Frank, The return type of zipn would have to depend on the number of arguments. If you are satisfied with all arguments having the same type, then you can use transpose: zipn list1 list2 .. listn => transpose [list1, list2, .. listn] Can we make a polyvariadic zipn that returns a [HList]? Seems

Re: [Haskell-cafe] zip3, zip4 ... -> zipn?

I was looking for something like this too. Note that Erlang can do this ;-) but Erlang is probably not so strongly typed, so it's easier to do? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

[Haskell-cafe] howto install ghc-6.7.* ?

i just don't get it. please, can anybody explaim me how to do that? i tried it the last few days with ghc-6.7.20070807, ghc-6.7.20070809, and ghc-6.7.20070810. it always results in a broken library (without Prelude): # ghc-pkg list /usr/local/lib/ghc-6.7.20070810/package.conf: {ghc-6.7.200708

[Haskell-cafe] arrow question HXT related

Hi, I think this is just a stupid arrow question. Still I cannot find where my mistake is located. Suppose I have a simple xml document I want to process with HXT: text After extracting I want to duplicate the children trees with the arrow operator (&&&) and process them to get e

[Haskell-cafe] Re: Small question [new Wiki page up]

Stefan O'Rear wrote: Good idea! Maybe it could be fit into the GHC Performance Resource somehow? (http://www.haskell.org/haskellwiki/Performance/GHC) OK. But it'll probably contain a lot of guessing to start with... ;-) Wiki pages can be fixed. Private misunderstandings can't,

Re: [Haskell-cafe] arrow question HXT related

On Sat, Aug 11, 2007 at 11:50:19AM +0200, Andrea Rossato wrote: > Hi, > > I think this is just a stupid arrow question. Still I cannot find > where my mistake is located. > well, it was not an arrow problem but a HXT problem. This new version of tryMe2 does work as expected: tryMe2 = runLA arro

[Haskell-cafe] Re: Language support for imperative code. Was: Re: monad subexpressions

Brian Hulley schrieb: apfelmus wrote: However, most "genuinely imperative" things are often just a building block for a higher level functional model. The ByteString library is a good example: the interface is purely functional, the internals are explicit memory control. It's a bad idea to let t

Re: [Haskell-cafe] How odd...

[Sorry for the long quote, but context is important] Dan Piponi wrote: It's fairly standard practice, when documenting functions of a complex variable, to specify precisely which 'branch cuts' are being used. Here's a quote from the Mathematica documentation describing their Log function: "Log[z

[Haskell-cafe] Re: zip3, zip4 ... -> zipn?

Frank Buss schrieb: Is it possible to write a function like this: zipn n list_1 list_2 list_3 ... list_n which implements zip3 for n=3, zip4 for n=4 etc.? Looks like variable number of arguments are possible, like printf shows, so a general zipn should be possible, too. If it is possible, why t

Re: [Haskell-cafe] zip3, zip4 ... -> zipn?

On 8/11/07, Frank Buss <[EMAIL PROTECTED]> wrote: > > Is it possible to write a function like this: > > zipn n list_1 list_2 list_3 ... list_n > > which implements zip3 for n=3, zip4 for n=4 etc.? Looks like variable > number > of arguments are possible, like printf shows, so a general zipn should

Re: [Haskell-cafe] Defining new operators

On 8/10/07, Shachaf Ben-Kiki <[EMAIL PROTECTED]> wrote: > > > Also consider using: > > > data Step = Step { ..., scenario :: Scenario, ... } Just to expand on Shachaf's answer, when defining a data type you can use a special record syntax to give names to each of the components, like this: data

Re: [Haskell-cafe] Dynamic thread management?

Hugh, I certainly think it would be wrong to declare that NDP is doomed to failure... not because you would be making an enemy of SPJ (I'm pretty sure you wouldn't!) but because it actually aims to solves a less ambitious problem: the problem of parallelising the SAME task applied to different dat

Re: [Haskell-cafe] Re: zip3, zip4 ... -> zipn?

On 8/11/07, apfelmus <[EMAIL PROTECTED]> wrote: > Frank Buss schrieb: > > Is it possible to write a function like this: > > > > zipn n list_1 list_2 list_3 ... list_n > > > > which implements zip3 for n=3, zip4 for n=4 etc.? Looks like variable number > > of arguments are possible, like printf show

Re: [Haskell-cafe] Dynamic thread management?

You guys might also want to take a look at the Cilk programming language, and how it managed threads. If you know C, learning Cilk is about 2 hours of work, as it's C with half a dozen extra keywords and a few new concepts. I'd love to see Cilk - C + Haskell as a programming language. The

Re: [Haskell-cafe] Dynamic thread management?

Brian Hurt wrote: The key idea of Cilk is that it's easier to deparallelize than it is to parallelize, especially automatically. So the idea is that the program is written incredibly parallel, with huge numbers of microthreads, which are (on average) very cheap to spawn. The runtime then dep

Re: [Haskell-cafe] Dynamic thread management?

On 11/08/07, Brian Hurt <[EMAIL PROTECTED]> wrote: > > You guys might also want to take a look at the Cilk programming language, > and how it managed threads. If you know C, learning Cilk is about 2 hours > of work, as it's C with half a dozen extra keywords and a few new > concepts. I'd love to

[Haskell-cafe] Haddock: documenting parameters of functional arguments

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? ___ Haskell-Cafe mailing list Haskell-Ca

Re[2]: [Haskell-cafe] Dynamic thread management?

Hello Brian, Saturday, August 11, 2007, 8:35:49 PM, you wrote: > The key idea of Cilk is that it's easier to deparallelize than it is to > parallelize, especially automatically. So the idea is that the program is > written incredibly parallel, with huge numbers of microthreads, which are > (on a

Re: [Haskell-cafe] Explaining monads

David Menendez wrote: > Be sure to read sigpfe's "You could have invented monads!" and the > Wadler paper. > > > > > Most tutorials try to explain

[Haskell-cafe] Re: zip3, zip4 ... -> zipn?

Frank Buss <[EMAIL PROTECTED]> wrote in article <[EMAIL PROTECTED]> in gmane.comp.lang.haskell.cafe: > Is it possible to write a function like this: > > zipn n list_1 list_2 list_3 ... list_n > > which implements zip3 for n=3, zip4 for n=4 etc.? Looks like variable number > of arguments are poss

[Haskell-cafe] Re: default for quotRem in terms of divMod?

Btw. is there any application, where 'quot' and 'rem' are needed? All occurrences of 'quot' and 'rem' I found in code so far were actually wrong and should have been 'div' and 'mod'. http://www.haskell.org/haskellwiki/Things_to_avoid#Forget_about_quot_and_rem _

Re: [Haskell-cafe] Explaining monads

On Sat, Aug 11, 2007 at 03:00:04PM -0400, Ronald Guida wrote: > The question remains: "What is special about Monad or ArrowApply, > compared to Arrow?" or "What is more general about Arrow, compared to > Monad or ArrowApply?" If all you have is an Arrow, then you must make up your mind what you're

Re: [Haskell-cafe] zip3, zip4 ... -> zipn?

On Sat, Aug 11, 2007 at 05:27:19PM +0800, Hugh Perkins wrote: > I was looking for something like this too. > > Note that Erlang can do this ;-) but Erlang is probably not so > strongly typed, so it's easier to do? I think the main issue is that Erlang doesn't use currying (IIRC). Currying makes i

Re: [Haskell-cafe] Re: default for quotRem in terms of divMod?

On Sat, 2007-08-11 at 21:10 +0200, Henning Thielemann wrote: > Btw. is there any application, where 'quot' and 'rem' are needed? All > occurrences of 'quot' and 'rem' I found in code so far were actually wrong > and should have been 'div' and 'mod'. > > http://www.haskell.org/haskellwiki/Things_to

Re: [Haskell-cafe] howto install ghc-6.7.* ?

On Sat, Aug 11, 2007 at 11:44:17AM +0200, Marc A. Ziegert wrote: > i just don't get it. > please, can anybody explaim me how to do that? > i tried it the last few days with ghc-6.7.20070807, ghc-6.7.20070809, and > ghc-6.7.20070810. > it always results in a broken library (without Prelude): > > #

[Haskell-cafe] IO within parser

I've been struggling with writing a parser that needs to parse include files within source files. So far I cannot get this to work (in reality to get work done I wrote a kludge that returns a list of include filenames to be run later in a pure IO function. I realized that this just amounted to

Re: [Haskell-cafe] IO within parser

Gregory Propf wrote: I've been struggling with writing a parser that needs to parse include files within source files. So far I cannot get this to work (in reality to get work done I wrote a kludge that returns a list of include filenames to be run later in a pure IO function. I realized tha

Re: [Haskell-cafe] Re: zip3, zip4 ... -> zipn?

> Also, applicative functors can help > > GHCi> :m +Control.Applicative > GHCi> (\x y z -> x*(y+z)) <$> ZipList [1,2,3] > <*> ZipList [-1,0,1] <*> ZipList [1,1,1] > ZipList [0,2,6] > GHCi> http://www.soi.city.ac.uk/~ross/papers/Applicative.pdf quote "The general scheme is as follow

Re: [Haskell-cafe] Re: default for quotRem in terms of divMod?

Henning Thielemann wrote: Btw. is there any application, where 'quot' and 'rem' are needed? All occurrences of 'quot' and 'rem' I found in code so far were actually wrong and should have been 'div' and 'mod'. http://www.haskell.org/haskellwiki/Things_to_avoid#Forget_about_quot_and_rem Yes, my

Re: [Haskell-cafe] Re: default for quotRem in terms of divMod?

Isaac Dupree wrote: I do think that if you almost always want to _use_ div and mod, you should be able to just define div and mod too (not quot and rem) that was unclear - I mean you should have that choice, not that it should be disallowed to define quot and rem only! Isaac

Re: [Haskell-cafe] howto install ghc-6.7.* ?

Same problem here. I downloaded the ghc-6.7.20070811.tar.bz2 snapshot build on amd64 under ubuntu. >From the README > The "sh boot" step is only necessary if this is a tree checked out > from darcs. For source distributions downloaded from GHC's web site, > this step has already been performed.

Re: [Haskell-cafe] Dynamic thread management?

On Sat, 11 Aug 2007, Sebastian Sylvan wrote: How is this any better than using "par" in Haskell? Mainly how the threads are actually scheduled. Mind you, I'm an *incredible* Haskell newbie, so take all of my comments with a 5-pound salt block, but as I understand how the current implement

Re: [Haskell-cafe] zip3, zip4 ... -> zipn?

On Sunday 12 August 2007 05:24, Stefan O'Rear wrote: > Currying makes it MUCH harder to implement varargs functions. That's interesting - why is that the case? Alexis. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mail

Re: [Haskell-cafe] zip3, zip4 ... -> zipn?

On Sun, Aug 12, 2007 at 12:56:31PM +1000, Alexis Hazell wrote: > On Sunday 12 August 2007 05:24, Stefan O'Rear wrote: > > > Currying makes it MUCH harder to implement varargs functions. > > That's interesting - why is that the case? varsum 2 3 -- varsum receives 2, and returns a function, whi

[Haskell-cafe] Infinity v0.1

Hello! Over the past couple of days I've been working on an IRC bot in the essence of lambdabot; that is, it should be extendable through plugins and plugins should be easy to write, modify and contribute. I also wanted the bot to be small in terms of LOC (as of 0.1, about ~360 including the two b

Re: [Haskell-cafe] Re: towards a new foundation for set theory with atoms

On Fri, Aug 10, 2007 at 03:54:23PM -0700, Greg Meredith wrote: > Haskellians, > > A quick follow up. If you look at the code that i have written there is a > great deal of repeated structure. Each of these different kinds of sets and > atoms are isomorphic copies of each other. Because, however, o

Re: [Haskell-cafe] Re: default for quotRem in terms of divMod?

On Sat, 11 Aug 2007, Derek Elkins wrote: > On Sat, 2007-08-11 at 21:10 +0200, Henning Thielemann wrote: > > Btw. is there any application, where 'quot' and 'rem' are needed? All > > occurrences of 'quot' and 'rem' I found in code so far were actually wrong > > and should have been 'div' and 'mod'

Fw: [Haskell-cafe] IO within parser

Well the docs ( http://legacy.cs.uu.nl/daan/download/parsec/parsec.html ) hint that setInput and getInput are good for this. I can certainly how they *would* be - if I knew how to pull in files within the parse. Actually I use those functions to do multiple recursive passes but of course you a

Re: [Haskell-cafe] Explaining monads

Stefan O'Rear wrote: > On Sat, Aug 11, 2007 at 03:00:04PM -0400, Ronald Guida wrote: >> The question remains: "What is special about Monad or ArrowApply, >> compared to Arrow?" or "What is more general about Arrow, compared >> to Monad or ArrowApply?" > > If all you have is an Arrow, then you must

Re: Fw: [Haskell-cafe] IO within parser

Hello Gregory, Sunday, August 12, 2007, 9:32:04 AM, you wrote: >> I've been struggling with writing a parser that needs to parse include >> files within source files.   Parsec can't accomplish with without using unsafePerformIO because it's monad is pure. it's algorithmically impossible to have