Re: [Haskell-cafe] windows network programming

Am 02.11.2010 01:20, schrieb Paulo Tanimoto: http://hackage.haskell.org/package/network You just have to remember that you need to call "withSocketsDo" on windows before doing anything with the network library. ___ Haskell-Cafe mailing list Haskell-

Re: [Haskell-cafe] Am I using type families well?

I understand your point Ryan, but in that case, why didn't the error occur when Resource and ResourceId were separated classes? BTW, I assume for your Int instance of Resource, you meant: > instance Resource Int where > type IdOf *Int* = Int > type LocOf *Int* = String > type CfgOf *Int* = (

Re: [Haskell-cafe] What is simplest extension language to implement?

Forth is quite easy to implement, but can it be used as extension language? Wiki describes it as quite low level... TCL ... Well, I'll consider it if it have written standart, like RxRS does. On 11/02/2010 09:31 AM, Miguel Mitrofanov wrote: > Ehm... Forth? TCL? > > Отправлено с iPhone > > Nov 2, 20

Re: [Haskell-cafe] What is simplest extension language to implement?

I haven't ever used it myself, but I've heard good things about Lua, which was designed to be an embedded scripting language for applications: http://www.lua.org/ If you believe the Programming Language Shootout (http://shootout.alioth.debian.org/) it is pretty fast for a dynamic interpre

Re: [Haskell-cafe] What is simplest extension language to implement?

Or maybe Lua? There is already a Lua binding on Hackage. I've been advised to use it when I was also looking for a scripting language (and disadvised to use Scheme). 2010/11/2 Permjacov Evgeniy > Let us think, that we need some scripting language for our pure haskell > project and configure-com

Re: [Haskell-cafe] What is simplest extension language to implement?

Norman Ramsey has implemented Lua as an extension language for ML, this included actually writing a Lua interpreter not FFI-ing to the standard Lua. He has a series of good papers about the mechanics of exposing the API of an application to the scripting language. The code itself is available as p

Re: [Haskell-cafe] template haskell for typeclass synonyms

It's first time I use TH. It would be nice to point out the motivations for using it. If everything TH does is doable without it, the point of using it is write less code, eliminating some necessary and automatically computable code. But I guess there is some more . paolino 2010/11/2 Antoine

Re: [Haskell-cafe] Reference for technique wanted

On 2 November 2010 04:18, Richard O'Keefe wrote: [SNIP] > SML/NJ MLton >  0.899 0.244    boring old plain list >  5.481 1.244    build a "raum" using raums >  8.186 1.380    build a raum then convert it to a list > 12.581 4.449    build a "dlist" using dlists > 16.209 5.096    build a dlist then

Re: [Haskell-cafe] Is "let" special?

2010/11/2 Günther Schmidt : > I've been given a few hints over time when I asked question concerning DSLs > but regretfully didn't follow them up. I think this is probably to do with observable sharing. The problem in DSLs is if you have: fact :: Term -> Term fact = Factorial instance Num Term w

Re: [Haskell-cafe] What is simplest extension language to implement?

I don't understand. Why don't you use Haskell as the scripting language? On Tue, Nov 2, 2010 at 7:04 AM, Permjacov Evgeniy wrote: > Let us think, that we need some scripting language for our pure haskell > project and configure-compile-run is not a way. In such a case a > reasonably simple, yet

Re: [Haskell-cafe] What is simplest extension language to implement?

Because he would have either to recompile the whole program or to use things like hint, both implying that GHC must be installed on the user side (600Mo+ for GHC 6.12.3) 2010/11/2 Lennart Augustsson > I don't understand. Why don't you use Haskell as the scripting language? > > On Tue, Nov 2, 2

Re: [Haskell-cafe] Reference for technique wanted

Interesting discussion. I still think it is the same idea, namely to represent not-yet-known list tails by variables, embedded into two different kinds of languages. \rest->start++rest [start|rest]\rest-- '\' is an infix constructor Savvy Prolog programmers wouldn't *DREAM* of using

Re: [Haskell-cafe] What is simplest extension language to implement?

ehm. I missed something and ghc api is well documented and stable ? The problem is that haskell is overkill here and it requires esoteric extensions for some tasks (Rank2Types for reflection, for example). It is inacceptable for scripting language, faced to no-programmers. Such languages must be a

Re: [Haskell-cafe] What is simplest extension language to implement?

On 11/02/2010 10:40 AM, Yves Parès wrote: Because he would have either to recompile the whole program or to use things like hint, both implying that GHC must be installed on the user side (600Mo+ for GHC 6.12.3) Isn't there a way to use some stripped-down version of ghc and the base libraries,

Re: [Haskell-cafe] Is Curry alive?

Hi Gregory, On Nov 2, 2010, at 9:27 AM, Gregory Crosswhite wrote: I was thinking about using Curry, but it looks to me like the language is dead and hasn't seen much activity for a few years. The community is smaller than the Haskell community but the PAKCS system is still actively develop

Re: [Haskell-cafe] What is simplest extension language to implement?

Yves Parès schrieb: > Because he would have either to recompile the whole program or to use > things like hint, both implying that GHC must be installed on the user > side (600Mo+ for GHC 6.12.3) Hugs is great for running small Haskell "scripts". ___ H

Re: [Haskell-cafe] Is "let" special?

Fundera på vad parentesen innebär. / Emil 2010-11-02 10:20, Max Bolingbroke skrev: To recover this sharing, you either need some sort of observable sharing, or some common subexpression elimination (which risks introducing space leaks if your DSL has lazy semantics). _

Re: [Haskell-cafe] install GHC 7.0.1 RC on OS X?

you can: mv /Library/Frameworks/GHC.framework /Library/Frameworks/GHC.framework.2 then install GHC 7 just toggle between those paths to switch version ... On Tue, Nov 2, 2010 at 1:07 AM, Edward Amsden wrote: > I'd like to install the GHC 7.0.1 RC on my mac (Snow Leopard, x86_64), > but I don'

Re: [Haskell-cafe] Is "let" special?

Sorry, that was a mental note to myself :) / Emil 2010-11-02 12:41, Emil Axelsson skrev: Fundera på vad parentesen innebär. / Emil 2010-11-02 10:20, Max Bolingbroke skrev: To recover this sharing, you either need some sort of observable sharing, or some common subexpression elimination (wh

Re: [Haskell-cafe] What is simplest extension language to implement?

On Tue, 2 Nov 2010, Henning Thielemann wrote: Yves Parès schrieb: Because he would have either to recompile the whole program or to use things like hint, both implying that GHC must be installed on the user side (600Mo+ for GHC 6.12.3) Hugs is great for running small Haskell "scripts". I l

Re: [Haskell-cafe] Mysterious fact

FYI, I implemented an error monad using this church-encoded either instead of the conventional either. my thought was that since you skip the conditional at each bind call you'd get better performance. I was quite mistaken. Max On Nov 2, 2010, at 6:40 AM, Jeremy Shaw wrote: > Looks a lot l

[Haskell-cafe] DSL libraries (Was: Map constructor in a DSL)

Hello Steffen, can you compile AwesomePrelude? I've got error messages (see below). By the way, I've looked at some DSLs made in Haskell, if I don't mistake there are lots of similarities between them. There similarities could be put in a library to help the implementors of a DSL, more or less lik

Re: [Haskell-cafe] [ANNAUNCE] ghcjs-0.1.0 Haskell to Javascript compiler

On 01-11-10 22:35, Aaron Gray wrote: On 1 November 2010 16:04, Martijn Schrage > wrote: On 29-10-10 22:20, Aaron Gray wrote: ... What browser are you using, IE8, IE9, FF and Chrome on Windows throw up errors, both locally and to your above code.

Re: [Haskell-cafe] Scrap your rolls/unrolls

Max Bolingbroke wrote: > On 23 October 2010 15:32, Sjoerd Visscher wrote: > > A little prettier (the cata detour wasn't needed after all): > > > >   data IdThunk a > >   type instance Force (IdThunk a) = a > > Yes, this IdThunk is key - in my own implementation I called this "Forced", > so: > >

Re: [Haskell-cafe] What is simplest extension language to implement?

Clojure! Sent from my iPad On Nov 2, 2010, at 2:31, Miguel Mitrofanov wrote: > Ehm... Forth? TCL? > > Отправлено с iPhone > > Nov 2, 2010, в 9:04, Permjacov Evgeniy написал(а): > >> Let us think, that we need some scripting language for our pure haskell >> project and configure-compile-run

Re: [Haskell-cafe] Are newtypes optimised and how much?

Simon Peyton-Jones wrote: > What you really want is to say is something like this. Suppose my_tree :: > Tree String. Then you'd like to say > my_tree ::: Tree Foo > meaning "please find a way to convert m_tree to type (Tree Foo), using > newtype coercions. > > The exact syntax is a pro

Re: [Haskell-cafe] What is simplest extension language to implement?

Quoth Henning Thielemann , > Hugs is great for running small Haskell "scripts". The quotes around "scripts" are well chosen, since it sounds like you might be using the word in a different sense of `small program', vs. the extension language notion of a programmable UI. Haskell's suitability for

Re: [Haskell-cafe] What is simplest extension language to implement?

> Henning Thielemann, Tue, November 2, 2010 6:11:02 AM > > Yves Parès schrieb: > > Because he would have either to recompile the whole program or to use > > things like hint, both implying that GHC must be installed on the user > > side (600Mo+ for GHC 6.12.3) > > Hugs is great for running sma

[Haskell-cafe] non-hackage cabal repos? unpacking non-repo package tarballs?

I often find myself writing example code that I'd like to distribute via cabal, but without further burdening hackage with not generally useful packages. 1. The simplest approach would be if cabal could expose its internal 'unpackPackage' as a command, so that author: cabal sdist user: cab

Re: [Haskell-cafe] Mysterious fact

On 01/11/2010 10:40 PM, Jeremy Shaw wrote: Looks a lot like Church encoding to me: http://en.wikipedia.org/wiki/Church_encoding It was first discovered by the guy who invented lambda calculus :p Yes, well, the various Church encodings and the lambda calculus in general are where I got the i

Re: [Haskell-cafe] non-hackage cabal repos? unpacking non-repo package tarballs?

On 2 November 2010 19:02, Claus Reinke wrote: > 1. The simplest approach would be if cabal could expose > its internal 'unpackPackage' as a command, so that > >   author: cabal sdist >   user: cabal unpackPackage Example.tar.gz > [...] > 2. Failing that, I remembered that cabal used to be designed

Re: [Haskell-cafe] template haskell for typeclass synonyms

Well, Template Haskell is what you go to when what you want -can't- be reasonably expressed with standard GHC Haskell. It's something of a last resort (at least in my case). Typeclass synonyms can be faked reasonably well with UndecidableInstances, but if you want to, for example, automatically gen

Re: [Haskell-cafe] windows network programming

got any urls with examples? On Tue, Nov 2, 2010 at 12:17 AM, Nils Schweinsberg wrote: > Am 02.11.2010 01:20, schrieb Paulo Tanimoto: >> >> http://hackage.haskell.org/package/network > > You just have to remember that you need to call "withSocketsDo" on windows > before doing anything with the net

[Haskell-cafe] CPS Error Monad

> From: Max Cantor > Sent: Tue, November 2, 2010 7:58:49 AM > > FYI, > > I implemented an error monad using this church-encoded either instead of > the >conventional either. my thought was that since you skip the conditional at >each bind call you'd get better performance. I was quite m

[Haskell-cafe] Can a fundep force parametricity

I would like to make a two-parameter type class where some choices of the first type uniquely determine the second type, and other choices of the first type promise to work with any choice of the second type. This code seems a bit suspicious, but is accepted thanks to UndecidableInstances. >{-#

Re: [Haskell-cafe] windows network programming

Am 02.11.2010 19:57, schrieb Michael Litchard: got any urls with examples? Sure, see this short server-client-ping-pong application. By the way, I noticed that you don't need withSocketsDo on windows 7, but I guess it's there for a reason for older windows versions. :) import Control.

Re: [Haskell-cafe] Mysterious fact

Hi, Am Montag, den 01.11.2010, 22:28 + schrieb Andrew Coppin: > The other day, I accidentally came up with this: > > {-# LANGUAGE RankNTypes #-} > > type Either x y = forall r. (x -> r) -> (y -> r) -> r > > left :: x -> Either x y > left x f g = f x > > right :: y -> Either x y > right y f

Re: [Haskell-cafe] Can a fundep force parametricity

On Tuesday 02 November 2010 4:01:33 pm Brandon Moore wrote: > >instance C Int b where > > > > update _ n = n This instance violates the fundep. The fundep says that the first parameter determines the second. However, this instance is a scheme for declaring infinitely many monomorphic instances

[Haskell-cafe] Re: Mysterious fact

Andrew Coppin writes: > The other day, I accidentally came up with this: > > |{-# LANGUAGE RankNTypes #-} > > type Either x y= forall r. (x -> r) -> (y -> r) -> r > > left :: x -> Either x y > left x f g= f x > > right :: y -> Either x y > right y f g= g y > > | > > This is one exam

Re: [Haskell-cafe] CPS Error Monad

On Tue, Nov 2, 2010 at 2:11 PM, Brandon Moore wrote: >> From: Max Cantor >> Sent: Tue, November 2, 2010 7:58:49 AM >> >> FYI, >> >> I  implemented an error monad using this church-encoded either  instead of >> the >>conventional either.  my thought was that since you skip the  conditional at >>e

Re: [Haskell-cafe] CPS Error Monad

On Tuesday 02 November 2010 3:11:22 pm Brandon Moore wrote: > That's surprising, I think LogicT gains significant performance from that > sort of CPS conversion. It's probably not that surprising. LogicT is an encoding of a recursive type, so there's potentially more causes for the gain. For ins

[Haskell-cafe] trying to use Tag Soup - fromAttrib

I have the following TagOpen [TagOpen "a" [("href","/launchWebForward.do?resourceId=4&policy=0&returnTo=%2FshowWebForwards.do")]] I would like to get the attribute resourceId=4 from that. My understanding is that fromAttrib is the right thing to use. But I'm having difficulty understanding the ty

Re: [Haskell-cafe] trying to use Tag Soup - fromAttrib

On Tuesday 02 November 2010 22:17:48, Michael Litchard wrote: > I have the following TagOpen > [TagOpen "a" > [("href","/launchWebForward.do?resourceId=4&policy=0&returnTo=%2FshowWeb >Forwards.do")]] > > I would like to get the attribute resourceId=4 from that. My > understanding is that fromAttrib

[Haskell-cafe] Linker errors when using the Hipmunk library

Hello, I have installed the Hipmunk physics library (5.2.0.1) using cabal-install, but whenever I try to compile a program that uses it (e.g. the HipmunkPlayground package), I get the following linker error: > $ cabal install hipmunkplayground > Resolving dependencies... > Configuring HipmunkPlay

Re: [Haskell-cafe] trying to use Tag Soup - fromAttrib

Daniel, Thank you for your reply. I'm still confused. When I see a code sample like this main = do posts <- liftM parseTags (readFile "posts.xml") print $ head $ map (fromAttrib "Id") $ filter (~== ("")) posts I have no idea how to match that up wit

Re: [Haskell-cafe] trying to use Tag Soup - fromAttrib

On 2 November 2010 22:40, Michael Litchard wrote: > fromAttrib :: (Show str, Eq str, StringLike str) => str -> Tag str -> str > > seems to say "fromAttrib takes two parameters (I know it doesn't > literally take two), one str (with the constraints in parenthesis to > the left) and one str of type

Re: [Haskell-cafe] trying to use Tag Soup - fromAttrib

Excerpts from Michael Litchard's message of Tue Nov 02 22:40:27 +0100 2010: > Daniel, >Thank you for your reply. I'm still confused. > When I see a code sample like this > main = do > posts <- liftM parseTags (readFile "posts.xml") > print $ head $ map (fromAttrib "Id") $ >

Re: [Haskell-cafe] Am I using type families well?

On Tue, Nov 2, 2010 at 12:32 AM, Yves Parès wrote: > I understand your point Ryan, but in that case, why didn't the error occur > when Resource and ResourceId were separated classes? Because there was only one "retrieveLoc" for a particular IdOf, even if resources shared an IdOf. i.e. instance

Re: [Haskell-cafe] trying to use Tag Soup - fromAttrib

Ah thank you. I can go ahead and figure out how to parse that string. Using a regex is tempting but I have a feeling I can get something more maintainable if I use another approach. On Tue, Nov 2, 2010 at 2:52 PM, Daniel Schoepe wrote: > Excerpts from Michael Litchard's message of Tue Nov 02 22:4

Re: [Haskell-cafe] Linker errors when using the Hipmunk library

Hipmunk is a bit of an oddity in that the Hackage package bundles the original C library along with Haskell binding. The first step would be to check that the C library has been built properly - the build type in the cabal file is "Simple" but I don't know if this would cause the C lib to be built

Re: [Haskell-cafe] Re: Mysterious fact

Jon, you beat me to it. I was going to mention Ponder. But Ponder did have a builtin type, it had the function type built in. :) -- Lennart On Tue, Nov 2, 2010 at 9:47 PM, Jon Fairbairn wrote: > Andrew Coppin writes: > >> The other day, I accidentally came up with this: >> >> |{-# LANGUAGE

[Haskell-cafe] change in overlapping instance behavior between GHC 6.12 and GHC 7 causes compilation failure

Hello, I have a module, XMLGenerator, which has some overlapping instances. I have a second module, Test, which imports that module and also adds some more overlapping instances. Both modules contain {-# LANGUAGE OverlappingInstances #-} at the top. Under some old version of 6.13 (and probably 6

Re: [Haskell-cafe] trying to use Tag Soup - fromAttrib

Hi Michael, If you just replace all 'str' with 'String' when reading the signature then that will almost certainly be sufficient for your purposes. So read it as: fromAttrib :: String -> Tag String -> String Where "Tag String" can be thought of as just "Tag". If you try to parse HTML with regula

[Haskell-cafe] problems installing latest parsec

Here's what cabal says I have installed * parsec Synopsis: Monadic parser combinators Latest version available: 3.1.0 Latest version installed: 2.1.0.1 Homepage: http://www.cs.uu.nl/~daan/parsec.html License: BSD3 but here is what happens when I try to upgrade cabal upgrad

Re: [Haskell-cafe] What is simplest extension language to implement?

On Tue, Nov 2, 2010 at 11:08 AM, Donn Cave wrote: > The quotes around "scripts" are well chosen, since it sounds like > you might be using the word in a different sense of `small program', > vs. the extension language notion of a programmable UI. > > Haskell's suitability for something like this

Re: [Haskell-cafe] What is simplest extension language to implement?

On 2/11/2010 9:05 PM, Steffen Schuldenzucker wrote: On 11/02/2010 10:40 AM, Yves Parès wrote: Because he would have either to recompile the whole program or to use things like hint, both implying that GHC must be installed on the user side (600Mo+ for GHC 6.12.3) Isn't there a way to use some s

Re: [Haskell-cafe] problems installing latest parsec

On Wednesday 03 November 2010 00:46:13, Michael Litchard wrote: > Here's what cabal says I have installed > > > * parsec > Synopsis: Monadic parser combinators > Latest version available: 3.1.0 > Latest version installed: 2.1.0.1 > Homepage: http://www.cs.uu.nl/~daan/parsec.html >

Re: [Haskell-cafe] vector-space and standard API for vectors

> Vector (Complex a) is a vector with respect to both 'a' and 'Complex a'. Even worse, () is a vector w.r.t. *every* scalar type. On Sat, Oct 30, 2010 at 3:07 AM, Henning Thielemann < schlepp...@henning-thielemann.de> wrote: > wren ng thornton schrieb: > > On 10/22/10 8:46 AM, Alexey Khudyakov w

Re: [Haskell-cafe] problems installing latest parsec

thanks, it seems to be fine now. On Tue, Nov 2, 2010 at 5:04 PM, Daniel Fischer wrote: > On Wednesday 03 November 2010 00:46:13, Michael Litchard wrote: >> Here's what cabal says I have installed >> >> >> * parsec >>     Synopsis: Monadic parser combinators >>     Latest version available: 3.1.0

Re: [Haskell-cafe] Reference for technique wanted

On 2/11/2010, at 10:08 PM, Stephen Tetley wrote: > Och, adding reverse or even head and tail to a Dlist / Hughes list > seems out of spirit with the idea - build as a Hughes list (enjoying > cheap concat) - convert to a list and manipulate thereafter. I know > the version on Hackage has head, tail

Re: [Haskell-cafe] What is simplest extension language to implement?

Hello Permjacov, Tuesday, November 2, 2010, 9:04:00 AM, you wrote: > Let us think, that we need some scripting language for our pure haskell > project and configure-compile-run is not a way. In such a case a > reasonably simple, yet standartized and wide known language should be > implemented. Wh

Re: [Haskell-cafe] Reference for technique wanted

On 2/11/2010, at 10:44 PM, Claus Reinke wrote:I suspect you've researched the history of Prolog in more > > detail than I have, so I'll just remind you that Prolog wouldn't > have been successful without efficient implementations > (including structure sharing), Structure sharing came from theo

Re: [Haskell-cafe] Decoupling type classes (e.g. Applicative)?

-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 On 10/29/10 09:35 , Dominique Devriese wrote: > * Only introduce a dependency from type class A to type class B if all > functions in type class B can be implemented in terms of the > functions in type class A or if type class A is empty. Er? Eq

Re: profiling and strictness (was: Re: [Haskell-cafe] An interesting paper from Google)

> If this is accurate, why would anyone want to use the lazy State? To answer my own question, if you want a monad stack to produce lazy output. E.g. if you want to lazily produce data but also have exceptions and state: ErrorT e (LazyWriterT w (LazyStateT s Identity)) AFAIK this is the only wa

[Haskell-cafe] ffmpeg-tutorials fails to build

Hi, Info: ghc 6.12.3 (installed from haskell plataform) Mac os x snow leopard 10.6.4 ffmpeg instaled from ports - ffmpeg @0.6.1 hs-ffmpeg 0.3.4 - installed from cabal-install When I try compile this package, I get this erros: Linking dist/build/tutorial01/tutorial01 ... ld: warning: in /opt/lo

Re: [Haskell-cafe] Mysterious fact

On 11/1/10 6:28 PM, Andrew Coppin wrote: The other day, I accidentally came up with this: |{-# LANGUAGE RankNTypes #-} type Either x y= forall r. (x -> r) -> (y -> r) -> r left :: x -> Either x y left x f g= f x right :: y -> Either x y right y f g= g y | This is one example; it seems that j

Re: [Haskell-cafe] Is Curry alive?

On 11/2/10 7:09 AM, Sebastian Fischer wrote: On Nov 2, 2010, at 9:27 AM, Gregory Crosswhite wrote: Which does raise the question: when is it better to use a logic programming language instead of the list monad? It is more cumbersome to model logic variables and unification in a pure functional

Re: [Haskell-cafe] Is Curry alive?

On 11/2/10 8:37 PM, wren ng thornton wrote: Though I would suggest you look at the LogicT library instead of using actual lists... Also, you may be interested in reading the LogicT paper[2] or this paper[3] about search combinators in Haskell. Both offer a number of optimizations you should be

[Haskell-cafe] Non-hackage cabal source

I am trying to set up an apache server as an additional source to hackage for haskell packages. I have added to my ~/.cabal/config file: remote-repo: myhackage:http://myhackage/packages I am able to successfully make the HTTP requests: http://myhackage/packages/00-index.tar.gz http://myhackage/pa