Re: [Haskell-cafe] question about indentation conventions

I prefer the other style--as do others, evidently (see the example in my first reply.) I agree that this was a good discussion, but let's not conclude so easily that the entire community is in favor of one thing or the other. On Mon, Jul 1, 2013 at 8:24 PM, Richard Cobbe wrote: > On Sun, Jun 30

Re: [Haskell-cafe] question about indentation conventions

On Sun, Jun 30, 2013 at 07:53:08PM -0400, Richard Cobbe wrote: > Two questions: And what I've concluded by reading this thread: > 1) Are there wide-spread conventions in the Haskell community for how to > indent an application expression that's split across multiple lines? Well, there's general

Re: [Haskell-cafe] question about indentation conventions

On 2/07/2013, at 12:00 AM, Richard Cobbe wrote: > Sure. So my first question boils down to which of the two alternatives > below does the community prefer? (To be clear about the intended > semantics: this is the application of the function f to the arguments x, y, > and z.) > >f x >y

Re: [Haskell-cafe] question about indentation conventions

That's certainly true. As I mentioned, I was actually considering a *pretty-printer* rather than an automatic indentation tool per se. The end results are similar, but the pretty-printer is really only the latter part of the problem: it's predicated on already having a valid AST. My particular use

Re: [Haskell-cafe] question about indentation conventions

On Mon, Jul 1, 2013 at 9:56 AM, Tikhon Jelvis wrote: > I've thought about writing an automatic indenting tool for Haskell (or, > more accurately, a pretty-printer) for another project I have, and this is > the main thing that threw me off. While automatic indentation might make > sense for less e

Re: [Haskell-cafe] question about indentation conventions

<|> baz > > ~IRS > > From: haskell-cafe-boun...@haskell.org [haskell-cafe-boun...@haskell.org] > on behalf of Richard Cobbe [co...@ccs.neu.edu] > Sent: Monday, July 01, 2013 8:00 AM > To: haskell-cafe@haskell.org > Subject: Re:

Re: [Haskell-cafe] question about indentation conventions

On Mon, Jul 1, 2013 at 3:43 AM, Tom Ellis < tom-lists-haskell-cafe-2...@jaguarpaw.co.uk> wrote: > > is OK but > > f (g x > > y z) > > is not. > > It seems to me that this means > > f x1 x2 > x3 x4 > > is not. The OP was initially asking about this situation. > If you wrote th

Re: [Haskell-cafe] question about indentation conventions

___ From: haskell-cafe-boun...@haskell.org [haskell-cafe-boun...@haskell.org] on behalf of Richard Cobbe [co...@ccs.neu.edu] Sent: Monday, July 01, 2013 8:00 AM To: haskell-cafe@haskell.org Subject: Re: [Haskell-cafe] question about indentation conventions On Mon, Jul 01, 2013 at 05:

Re: [Haskell-cafe] question automatic indentation (and so on)

Hi, Am Montag, den 01.07.2013, 07:59 -0400 schrieb Richard Cobbe: > How does the indentation tool know if (a b c) is supposed to be the next > item in the do block, or merely a continuation of the previous application > of f? I would still expect the developer to write correctly intended Haskell,

Re: [Haskell-cafe] question about indentation conventions

On Mon, Jul 01, 2013 at 05:18:39PM +1200, Richard A. O'Keefe wrote: > > It looked pretty explicit to me: > > The golden rule of indentation > ... > you will do fairly well if you just remember a single rule: > Code which is part of some expression should be indented >

Re: [Haskell-cafe] question automatic indentation (and so on)

On Mon, Jul 01, 2013 at 09:48:42AM +0200, Joachim Breitner wrote: > I found https://github.com/jaspervdj/stylish-haskell/ (found via > http://stackoverflow.com/q/6870148/946226) which formats just some very > few aspects of Haskell. Does anyone have a more complete solution? Or is > interested i

Re: [Haskell-cafe] question about indentation conventions

> Code which is part of some expression should be indented > further in than the beginning of that expression [...] Yes. Then the next question is "how much further in". My answer is: it does not matter, but make it consistent (like 4 spaces), with the implication that indentation sh

Re: [Haskell-cafe] question automatic indentation (and so on)

Hi, on a related note: At HaL8 I was wondering how well Haskell would be suited for a workflow similar to what the go programmers do: Do not worry about code layout, but let the computer handle it! For more rationale and examples see http://golang.org/doc/effective_go.html#formatting While everyo

Re: [Haskell-cafe] question about indentation conventions

On Mon, Jul 01, 2013 at 05:18:39PM +1200, Richard A. O'Keefe wrote: > On 1/07/2013, at 1:04 PM, Richard Cobbe wrote: > > I should have been clearer in my original question: I'm curious about what > > to do when a multi-argument function application gets split across lines. > > That wiki page dicsus

Re: [Haskell-cafe] question about indentation conventions

On 1/07/2013, at 1:04 PM, Richard Cobbe wrote: > > I should have been clearer in my original question: I'm curious about what > to do when a multi-argument function application gets split across lines. > That wiki page dicsusses how the layout rule interacts with various special > forms (let, whe

Re: [Haskell-cafe] question about indentation conventions

The Haskell Style Guide is quite popular: https://github.com/tibbe/haskell-style-guide/blob/master/haskell-style.md (accompying elisp module: https://github.com/tibbe/haskell-style-guide/blob/master/haskell-style.el) I am not sure what the verdict is on functions spanning multiple lines, other tha

Re: [Haskell-cafe] question about indentation conventions

On Sun, Jun 30, 2013 at 05:41:46PM -0700, Darren Grant wrote: > Hi Richard, > > This page helped me when starting out: > http://en.wikibooks.org/wiki/Haskell/Indentation > On 2013-06-30 4:55 PM, "Richard Cobbe" wrote: > > 1) Are there wide-spread conventions in the Haskell community for how to

Re: [Haskell-cafe] question about indentation conventions

Hi Richard, This page helped me when starting out: http://en.wikibooks.org/wiki/Haskell/Indentation On 2013-06-30 4:55 PM, "Richard Cobbe" wrote: > I hope I'm not starting a holy war with this, but I'm curious about an > aspect of coding style that's been bugging me for a while, and I'm not > fi

[Haskell-cafe] question about indentation conventions

I hope I'm not starting a holy war with this, but I'm curious about an aspect of coding style that's been bugging me for a while, and I'm not finding much discussion of this question on the web or in the mailing list archives. Two questions: 1) Are there wide-spread conventions in the Haskell com

Re: [Haskell-cafe] Question about Newtype "op()" function arguments.

Ah, so is the idea, then, to use *op()* when `n` wasn't actually constructed formally, but rather "assembled" by the user, so as to match the type of the accessor function normally supplied as the argument to the constructor? On 6/7/2013 4:51 PM, Tom Ellis wrote: > On Fri, Jun 07, 2013 at 04:05:0

Re: [Haskell-cafe] Question about Newtype "op()" function arguments.

On 6/7/2013 4:51 PM, Tom Ellis wrote: On Fri, Jun 07, 2013 at 04:05:09PM -0400, Joe Q wrote: The phantom parameter solves the same problem as scoped type variables. Granted, if you find yourself in that kind of polymorphic soup you have deeper problems... I don't understand this. Scoped type v

Re: [Haskell-cafe] Question about Newtype "op()" function arguments.

On Fri, Jun 07, 2013 at 04:05:09PM -0400, Joe Q wrote: > The phantom parameter solves the same problem as scoped type variables. > Granted, if you find yourself in that kind of polymorphic soup you have > deeper problems... I don't understand this. Scoped type variables are used when you want to

Re: [Haskell-cafe] Question about Newtype "op()" function arguments.

The phantom parameter solves the same problem as scoped type variables. Granted, if you find yourself in that kind of polymorphic soup you have deeper problems... On Jun 7, 2013 2:53 PM, "Tom Ellis" < tom-lists-haskell-cafe-2...@jaguarpaw.co.uk> wrote: > On Fri, Jun 07, 2013 at 07:08:19AM -0700, D

Re: [Haskell-cafe] Question about Newtype "op()" function arguments.

On Fri, Jun 07, 2013 at 07:08:19AM -0700, David Banas wrote: > op :: > Newtype > n > o => (o -> n) -> n -> > oSource

Re: [Haskell-cafe] Question about Newtype "op()" function arguments.

* David Banas [2013-06-07 07:08:19-0700] > Hi All, > > Referring to the following, which is taken from the *Control.Newtype > *documentation > page: > > op :: > Newtype > n > o => (o -> n) -> n -> >

[Haskell-cafe] Question about Newtype "op()" function arguments.

Hi All, Referring to the following, which is taken from the *Control.Newtype *documentation page: op :: Newtype n o => (o -> n) -> n -> oSource

Re: [Haskell-cafe] question about "singletons"

Thanks Richard, now I have my answers. Richard Eisenberg wrote: > - The type system of Haskell is based on theoretical work that resolutely > assumes that types of non-* kind are uninhabited. While it is possible to > stretch imagination to allow types like 'Zero to be inhabited, the > designers

Re: [Haskell-cafe] question about "singletons"

On 6/1/13 3:18 PM, TP wrote: > In other words, bottom can be an inhabitant of a concrete type, not a type > constructor, which I can understand. But a type of kind Nat is a concrete > type, so why bottom cannot be an inhabitant of this type? The technical term is "proper type". That is, types are

Re: [Haskell-cafe] question about "singletons"

On Jun 1, 2013, at 8:18 PM, TP wrote: > > In other words, bottom can be an inhabitant of a concrete type, not a type > constructor, which I can understand. But a type of kind Nat is a concrete > type, so why bottom cannot be an inhabitant of this type? > >> We also have the nice maxim that ev

Re: [Haskell-cafe] question about "singletons"

Thanks Richard for your detailed answer. Please find my reply below (note I have rearranged some of your paragraphs). Richard Eisenberg wrote: > * Types at kind other than * do not have any inhabitants -- in fact, some > people would hesitate to call type-like things at kind other than * types! >

Re: [Haskell-cafe] question about "singletons"

#x27;re asking all the right questions! Richard -Original Message- From: haskell-cafe-boun...@haskell.org [mailto:haskell-cafe-boun...@haskell.org] On Behalf Of TP Sent: 31 May 2013 13:58 To: haskell-cafe@haskell.org Subject: [Haskell-cafe] question about "singletons" Hi all,

[Haskell-cafe] question about "singletons"

Hi all, Following a discussion on Haskell Cafe some time ago (1), Roman C. wrote: """ On the other hand, the type 'Succ 'Zero has kind 'Nat and doesn't have any inhabitants — only types of kind * do. """ Indeed, this is what seems to occur in the following example: --- {-#

Re: [Haskell-cafe] question about type constructors

* TP [2013-05-23 13:23:36+0200] > Roman Cheplyaka wrote: > > > The rule of thumb is that you should never use IncoherentInstances. > > > > The proper way to do it is: > > > > data Person :: Gender -> * where > > Person :: String -> Person b > > Child > > :: (PrettyPrint a,

Re: [Haskell-cafe] question about type constructors

Roman Cheplyaka wrote: > The rule of thumb is that you should never use IncoherentInstances. > > The proper way to do it is: > > data Person :: Gender -> * where > Person :: String -> Person b > Child > :: (PrettyPrint a, PrettyPrint b) > => String -> Person a -> Pe

Re: [Haskell-cafe] question about type constructors

* TP [2013-05-23 00:34:57+0200] > Hi, > > In the program I am trying to write, I have a problem that can be reduced to > the following dummy example: > > -- > {-# LANGUAGE GADTs #-} > {-# LANGUAGE DataKinds #-} > {-# LANGUAGE KindSignatures #-} > {-# LANGUAGE FlexibleIns

[Haskell-cafe] question about type constructors

Hi, In the program I am trying to write, I have a problem that can be reduced to the following dummy example: -- {-# LANGUAGE GADTs #-} {-# LANGUAGE DataKinds #-} {-# LANGUAGE KindSignatures #-} {-# LANGUAGE FlexibleInstances #-} {-# LANGUAGE IncoherentInstances #-} clas

Re: [Haskell-cafe] question about GADT and deriving automatically a Show instance

Denis Kasak wrote: > Note that all of this would work even without explicit quantification > since you > have already specified that Person accepts an argument of kind Gender. In > other > words, this works as expected: > > data Person :: Gender -> * where > Dead :: Person a > Alive :: {

Re: [Haskell-cafe] question about GADT and deriving automatically a Show instance

On 18 May 2013 11:16, TP wrote: > > However, I have not managed to make the version with forall work. Below, the > first occurrence of forall is ok, but the three following yield error. > > > {-# LANGUAGE GADTs #-} > {-# LANGUAGE StandaloneDeriving #-} > {

Re: [Haskell-cafe] question about GADT and deriving automatically a Show instance

Chris Wong wrote: >> data Person :: Gender -> * where >> Dead :: Person Gender -- WHAT DO I PUT HERE >> Alive :: { name :: String >> , weight :: Float >> , father :: Person Gender } -> Person Gender > > Here's the problem. In the line: > > Dead :: Person

Re: [Haskell-cafe] question about GADT and deriving automatically a Show instance

On Sat, May 18, 2013 at 9:11 AM, TP wrote: > > So the following version does not work: > > [..] > data Person :: Gender -> * where > Dead :: Person Gender -- WHAT DO I PUT HERE > Alive :: { name :: String > , weight :: Float >

Re: [Haskell-cafe] question about GADT and deriving automatically a Show instance

Adam Gundry wrote: [...] > To use standalone deriving, you need to write > >> deriving instance Show (Person gender) > > and everything will work fine. By writing > >> instance Show (Person gender) > > you are instead giving an instance with no methods, and the default > methods in the Show cl

Re: [Haskell-cafe] question about GADT and deriving automatically a Show instance

Hi TP, On 17/05/13 15:32, TP wrote: | [...] | | So I modify my code by removing "deriving Show", and adding the line: | | instance Show (Person gender) | | | But now, I obtain: | | $ runghc test_show.hs | GHC stack-space overflow: current l

[Haskell-cafe] question about GADT and deriving automatically a Show instance

Hi everybody, I have a question about deriving automatically a Show instance when using GADT. It works in this situation: {-# LANGUAGE GADTs #-} data Male data Female data Person gender where Dead :: Person gender Alive :: { name :: String , w

[Haskell-cafe] question about PutM patterns

Hello, cafe. I have a big problem using builders, so currently I'm using own builder based on Nettle one [1]. It uses Strict bytestring to build into and unchecked writes, thus it's very unsafe, plus other builders/PutM, developed rapidly so I like to switch to another one. However I use some patt

Re: [Haskell-cafe] Question about updating GHC on MacOS

>From my $0.2 experience, if you are planning of having multiple GHC installation, it would be better to do a fresh install using the bootstrapped GHC you can find on the website. Roughly I have done this way (on my Mac and on My EC2 instance): (inside a ghc bootstrapped folder) ./configure --pref

Re: [Haskell-cafe] Question about updating GHC on MacOS

I don't think so. However, you can install the OS X binaries for ghc 7.6.2 and make that sit just next to your Haskell Platform install. You can even use your existing cabal-install to install packages for the freshly installed ghc by doing 'cabal install foo --with-ghc=/path/to/ghc'. Just watch wh

[Haskell-cafe] Question about updating GHC on MacOS

Hi, I have Haskell Platform with GHC[i] 7.4.2 installed on a MacOS system. There's a problem with the handling of certain Markdown constructs in literate Haskell (lines starting with '#') that I understand is fixed in 7.6.2. Therefore, I'd like to be able to update my GHC installation to 7.6

Re: [Haskell-cafe] Question about forkIO

Hey Donn .. thanks, it turns out that threads do resume!!! This is how I got my gmail stuff working. I only have a doubt if the TCP "keep/alive" stuff continues to happen or not Regards, Kashyap On Thu, Feb 28, 2013 at 9:07 PM, Donn Cave wrote: > Quoth C K Kashyap , > ... > > Say I hav

Re: [Haskell-cafe] Question about forkIO

Quoth C K Kashyap , ... > Say I have a haskell function 'f' that does a forkIO and starts an action > "a". I create a DLL of this haskell code and inovke "f" from C. Can I > expect the "a" to continue to run once "f" has returned to C? Once control returns to f's caller, outside of the Haskell ru

Re: [Haskell-cafe] Question about forkIO

On Thu, Feb 28, 2013 at 6:09 AM, C K Kashyap wrote: > Say I have a haskell function 'f' that does a forkIO and starts an action > "a". I create a DLL of this haskell code and inovke "f" from C. Can I > expect the "a" to continue to run once "f" has returned to C? > While you're off in C the I/O

Re: [Haskell-cafe] Question about forkIO

Just to clarify, here is the sample haskell code that I am using - {-# LANGUAGE ForeignFunctionInterface #-} module Glue where import Foreign.C.String import qualified Control.Concurrent as CC funHaskell :: CString -> IO Int funHaskell cstr = do putStrLn "Haskell function called" str <-

[Haskell-cafe] Question about forkIO

Hi All, Say I have a haskell function 'f' that does a forkIO and starts an action "a". I create a DLL of this haskell code and inovke "f" from C. Can I expect the "a" to continue to run once "f" has returned to C? Regards, Kashyap ___ Haskell-Cafe mail

Re: [Haskell-cafe] question about: --hyperlink-source

On 13-02-21 05:18 AM, Doaitse Swierstra wrote: I ran into the problem that for the packages which I install using cabal install The generated html does not contain links to the sources. This issue was raised before in: http://stackoverflow.com/questions/1587635/haddock-for-cabal-installed-mod

Re: [Haskell-cafe] question about: --hyperlink-source

On 21 February 2013 21:18, Doaitse Swierstra wrote: > I ran into the problem that for the packages which I install using > > cabal install > > The generated html does not contain links to the sources. This issue was > raised before in: > > http://stackoverflow.com/questions/1587635/haddock-for-ca

[Haskell-cafe] question about: --hyperlink-source

I ran into the problem that for the packages which I install using cabal install The generated html does not contain links to the sources. This issue was raised before in: http://stackoverflow.com/questions/1587635/haddock-for-cabal-installed-modules I have been looking into the documentation

Re: [Haskell-cafe] Question about type inference of a GADT term

-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 Yes, of course! Stupid me, thanks for pointing that out Daniel. Now it works as expected. Florian On 09/22/2012 12:55 AM, Daniel Peebles wrote: > Shouldn't you have > > IxZero :: Ix (CtxCons ty ctx) ty > > instead of > > IxZero :: Ix ctx ty > >

Re: [Haskell-cafe] Question about type inference of a GADT term

Shouldn't you have IxZero :: Ix (CtxCons ty ctx) ty instead of IxZero :: Ix ctx ty On Fri, Sep 21, 2012 at 8:34 AM, Florian Lorenzen < florian.loren...@tu-berlin.de> wrote: > -BEGIN PGP SIGNED MESSAGE- > Hash: SHA1 > > Hello cafe, > > I have the following GADT definitions capturing th

[Haskell-cafe] Question about type inference of a GADT term

-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 Hello cafe, I have the following GADT definitions capturing the simply typed lambda calculus with de Bruijn indices for variables and explicitly annotated types for variables: {-# LANGUAGE GADTs #-} {-# LANGUAGE KindSignatures #-} {-# LANGUAGE DataK

Re: [Haskell-cafe] Question on proper use of Data.IORef

On Fri, Jun 22, 2012 at 11:18 AM, Captain Freako wrote: > Okay, I get it now. Thanks to all of you for your quick replies! > > So, here's what I need to do: > > My Haskell code gets called by a higher level C function and asked to > initialize itself. > As part of that initialization, I'm expected

Re: [Haskell-cafe] Question on proper use of Data.IORef

Okay, I get it now. Thanks to all of you for your quick replies! So, here's what I need to do: 1. My Haskell code gets called by a higher level C function and asked to initialize itself. 2. As part of that initialization, I'm expected to return a pointer to an instance of a particular

Re: [Haskell-cafe] Question on proper use of Data.IORef

On Fri, Jun 22, 2012 at 5:30 PM, Captain Freako wrote: >  12 main = do >  13 let theValue = 1 >  14 print theValue >  15 theValueRef <- newIORef theValue >  16 bump theValueRef >  17 return theValue theValue is a plain old immutable Haskell variable. "newIORef" creates an IORe

Re: [Haskell-cafe] Question on proper use of Data.IORef

theValueRef isn't a pointer to theValue that you can use to somehow change theValue (which is immutable). theValueRef is a reference to a "box" that contains a totally separate, mutable value. When you use newIORef to create theValueRef, it's *copying* theValue into the box. When you mutate theVal

[Haskell-cafe] Question on proper use of Data.IORef

Hi experts, I fear I don't understand how to properly use *Data.IORef*. I wrote the following code: 1 -- Testing Data.IORef 2 module Main where 3 4 import Data.IORef 5 6 bump :: IORef Int -> IO() 7 bump theRef = do 8 tmp <- readIORef theRef 9 let tmp2 = tmp + 1 10

Re: [Haskell-cafe] question about linking with sqlite3

I know it. I used a sqlite.dll file that is compiled for 32bit, while my computer is 64bit. sorry for this stupid question. On Thu, May 24, 2012 at 10:04 AM, Canhua wrote: > Hi, I made a cabal package that use HDBC-sqlite3 on Windows. > When cabal install it, I got an error from ld.exe: cannot

[Haskell-cafe] question about linking with sqlite3

Hi, I made a cabal package that use HDBC-sqlite3 on Windows. When cabal install it, I got an error from ld.exe: cannot find -lsqlite3. How can I tell ld.exe where sqlite3.dll is plcaed? Thanks. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http

Re: [Haskell-cafe] Question about concurrency, threads and GC

Hi! Thanks to all who responded! I got a lot of information to read and think about. For now I decided to use stm-channelize as the simplest approach which seem to be enough. On Mon, Mar 5, 2012 at 9:50 PM, Alexander V Vershilov wrote: > Hello. > > I've also written simple chat server based on c

Re: [Haskell-cafe] Question about concurrency, threads and GC

Hello. I've also written simple chat server based on conduits and stm channels https://github.com/qnikst/chat-server/blob/master/src/Main.hs it has quite similar aproach and maybe this solution can be used together to have better results. -- Alexander Vershilov Sat, Mar 03, 2012 at 02:05:17AM

Re: [Haskell-cafe] [haskell-cafe] Question about 64bit target on Windows platform

On Mon, Mar 5, 2012 at 2:54 PM, Simon Marlow wrote: > There is a possibility that the IHG might fund this during the next cycle, > which would mean that it would be in 7.6.1. > > Cheers, >Simon > > That is very good to hear!!! Regards, Kashyap

Re: [Haskell-cafe] [haskell-cafe] Question about 64bit target on Windows platform

There is a possibility that the IHG might fund this during the next cycle, which would mean that it would be in 7.6.1. Cheers, Simon On 05/03/2012 07:35, Jason Dagit wrote: I don't know if timeline has been established, but my understanding is that there is a need for this and that the

Re: [Haskell-cafe] [haskell-cafe] Question about 64bit target on Windows platform

Thank you Jason. On Mon, Mar 5, 2012 at 1:05 PM, Jason Dagit wrote: > I don't know if timeline has been established, but my understanding is > that there is a need for this and that the right people are aware of > it and looking into it. > > The GHC trac has a ticket for this: > http://hackage.h

Re: [Haskell-cafe] [haskell-cafe] Question about 64bit target on Windows platform

I don't know if timeline has been established, but my understanding is that there is a need for this and that the right people are aware of it and looking into it. The GHC trac has a ticket for this: http://hackage.haskell.org/trac/ghc/ticket/1884 On Sun, Mar 4, 2012 at 9:59 PM, C K Kashyap wrot

[Haskell-cafe] [haskell-cafe] Question about 64bit target on Windows platform

Hi All, Can someone please let me know if there is a 64bit target on Windows on the horizon for GHC? I am trying to push for changing the current implementation in my organization in C++ to Haskell - Our primary targets are Windows and Mac. Not being able to generate 64bit DLL's on Windows would be

Re: [Haskell-cafe] Question about concurrency, threads and GC

On Sat, Mar 3, 2012 at 12:50 PM, Alp Mestanogullari wrote: > That's exactly what I would have needed, several times in the past 2 > years. I've been wondering about a good way to abstract this to have a > library where you'd just plug your "business logic" and thus not have to > care anymore about

Re: [Haskell-cafe] Question about concurrency, threads and GC

Hi, On Sat, Mar 3, 2012 at 10:38 AM, Gregory Collins wrote: > Hi, > > The tutorial I gave for CUFP 2011 was a multi-user web chat program using > the Snap Framework. STM channels make this kind of problem super-easy to > deal with. Don't be afraid of forking lots of Haskell threads for programs >

Re: [Haskell-cafe] Question about concurrency, threads and GC

On Fri, Mar 2, 2012 at 5:19 PM, Paul Graphov wrote: > Hello Cafe! > > I am trying to implement networked application in Haskell. It should > accept many > client connections and support bidirectional conversation, that is not > just loop with > Request -> Response function but also sending notifi

Re: [Haskell-cafe] Question about concurrency, threads and GC

On Fri, Mar 2, 2012 at 7:34 PM, Joey Adams wrote: > I'll try to put together a simple chat server example, like the one I > wrote for stm-channelize. Here it is: https://github.com/joeyadams/haskell-chat-server-example See, in particular, the serveLoop function. When a message is received

Re: [Haskell-cafe] Question about concurrency, threads and GC

Fri, Mar 02, 2012 at 07:34:41PM -0500, Joey Adams wrote > On Fri, Mar 2, 2012 at 3:04 PM, Alexander V Vershilov > wrote: > > Hello, Paul. > > > > It seems you should not use 3 threads, but run in a data-driven behaviour > > with > > one thread per client. > > I don't think this will work for Pau

Re: [Haskell-cafe] Question about concurrency, threads and GC

On Fri, Mar 2, 2012 at 3:04 PM, Alexander V Vershilov wrote: > Hello, Paul. > > It seems you should not use 3 threads, but run in a data-driven behaviour with > one thread per client. I don't think this will work for Paul's situation. He needs to be able to send notifications to clients. This m

Re: [Haskell-cafe] Question about concurrency, threads and GC

Hello, Paul. It seems you should not use 3 threads, but run in a data-driven behaviour with one thread per client. You can take a look at network-conduit [1] example, there is a very good aproach to tcp-network application. There are some iteratee based examples but they are not so extensible. [

[Haskell-cafe] Question about concurrency, threads and GC

Hello Cafe! I am trying to implement networked application in Haskell. It should accept many client connections and support bidirectional conversation, that is not just loop with Request -> Response function but also sending notifications to clients etc. NB: I came from C++ background and used to

Re: [Haskell-cafe] question about conduit source

Hello. Naming operator >=< instead of >=> is a good idea. But this functions are looks very good and will make code easier to understand. Also I'll try using non-STM channel (as Michael adviced) because in such a task I don't need all STM power. Thanks for response. -- Alexander Tue, Feb 28

Re: [Haskell-cafe] question about conduit source

Finally, I've uploaded a new version of stm-conduit [1] with these combinators included. You should "cabal update" and then "cabal install stm-conduit" to get the latest version, and now you can vertically compose your sources! Regards, - clark [1] http://hackage.haskell.org/package/stm-conduit

Re: [Haskell-cafe] question about conduit source

First of all, I'd probably name that operator >=<, since >=> is Kleisli composition in Control.Monad. Second, you're going to need new threads for this, since you'll be reading from two sources concurrently. This isn't as big a problem as you might think, because Haskell threads are dirt cheap, or

Re: [Haskell-cafe] question about conduit source

On Tue, Feb 28, 2012 at 6:04 PM, Alexander V Vershilov wrote: > Hello, cafe. > > Is it possible to read data from different concurrent sources, > i.e. read data from source as soon as it become avaliable, e.g. > >  runResourceT $ (source1 stdin $= CL.map Left) >                   >=> (source2 hand

[Haskell-cafe] question about conduit source

Hello, cafe. Is it possible to read data from different concurrent sources, i.e. read data from source as soon as it become avaliable, e.g. runResourceT $ (source1 stdin $= CL.map Left) >=> (source2 handle $= CL.map Right) $= application $$ sink

[Haskell-cafe] question in install gtk2hs's webkit hackage

hi, I am cabal-installing webkit hackage on windows, and get a error: pkg-config pckage webkit-1.0 version > 1.1.15 is required but could be not found What should I next? install webkit? How to? I find there is a webkitgtk+ project. Which one should I install. I have try to install both of them

Re: [Haskell-cafe] question regarding Data.Array.Accelerate

Nevermind, I just realised I got something mixed up. Sorry to bother you. -- View this message in context: http://haskell.1045720.n5.nabble.com/question-regarding-Data-Array-Accelerate-tp5476144p5476586.html Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com. __

[Haskell-cafe] question regarding Data.Array.Accelerate

Hi, I have read the papers about the accelerate package that provides a high-level interface to nvidia's cuda library and am very intrigued. However, I have some start-up problems. Is this the right place for such questions? In particular, I'm having trouble with lifting and unlifting. From wh

Re: [Haskell-cafe] Question on `runState'

On Mon, Oct 17, 2011 at 5:32 PM, Conrad Parker wrote: > On 17 October 2011 23:59, Captain Freako wrote: >> In this excerpt from the `StateArrow' page: >> >> runState :: Arrow a => StateArrow s a e b -> a (e, s) (b, s)Source >> >> what's the significance of having written "StateArrow s a e b", ins

Re: [Haskell-cafe] Question on `runState'

On 17 October 2011 23:59, Captain Freako wrote: > In this excerpt from the `StateArrow' page: > > runState :: Arrow a => StateArrow s a e b -> a (e, s) (b, s)Source > > what's the significance of having written "StateArrow s a e b", instead of > "StateArrow s a b c"? In the context of that page,

[Haskell-cafe] Question on `runState'

In this excerpt from the `StateArrow' page: runState :: Arrowa => StateArrows a *e*

Re: [Haskell-cafe] Question, re: using Automaton

Captain Freako (quoting Control.Arrow.Transformer.Automaton): > Encapsulating an automaton by running it on a stream of inputs, obtaining a > stream of outputs. > Typical usage in arrow notation: > proc p -> do > ... > ys <- (|runAutomaton (\x -> ...)|) xs

Re: [Haskell-cafe] Question, re: using Automaton

Captain Freako wrote: > Encapsulating an automaton by running it on a stream of inputs, > obtaining a stream of outputs. > > Typical usage in arrow notation: > > proc p -> do > ...*ys <- (|runAutomaton (\x -> ...)|) xs* > > Here xs refers to the input stream and x

[Haskell-cafe] Question, re: using Automaton

Hi all, In this excerpt from the Automatonpage: runAutomaton :: (ArrowLoopCa,

Re: [Haskell-cafe] Question: Lazy Incremental Evaluation and Haskell?

On 10/08/2011 12:46 PM, Jan-Willem Maessen wrote: On Fri, Oct 7, 2011 at 2:46 PM, Brandon Moore wrote: Margnus Carlsson did something monadic several years ago. http://dl.acm.org/citation.cfm?doid=581478.581482 Perhaps there is an implementation on Hackage or on his website. This stuff also

Re: [Haskell-cafe] Question on definition of `parse' function in Parsec library.

Am 08.10.2011 16:04, schrieb Captain Freako: Hi all, In this definition from the Parsec library: parse :: (Stream s Identity t) => Parsec s () a -> SourceName -> s -> Either ParseError a parse p = runP p () what's the significance of `Identity t'? (`t' isn't used

Re: [Haskell-cafe] Question on definition of `parse' function in Parsec library.

Wow... my bad. Stream is in no way a monad transformer. I really should read before speaking... Stream s m t is such as "An instance of Stream has stream type s, underlying monad m and token type t determined by the stream" ( http://hackage.haskell.org/packages/archive/parsec/3.1.1/doc/html/Text-P

Re: [Haskell-cafe] Question on definition of `parse' function in Parsec library.

If I have this right, Stream is a monad transformer. Stream s m t means that it parses 's', is stacked with monad 'm' and has a result of type 't' So Identity is a monad, the simplest monad, defined as such: newtype Indentity t = Identity { runIdentity :: t } It's the identity monad, that does n

Re: [Haskell-cafe] Question: Lazy Incremental Evaluation and Haskell?

On Fri, Oct 7, 2011 at 2:46 PM, Brandon Moore wrote: >> Margnus Carlsson did something monadic several years ago. >> >> http://dl.acm.org/citation.cfm?doid=581478.581482 >> >> Perhaps there is an implementation on Hackage or on his website. >> >> This stuff also goes by the moniker "adaptive compu

[Haskell-cafe] Question on definition of `parse' function in Parsec library.

Hi all, In this definition from the Parsec library: parse :: (Stream s Identity t) => Parsec s () a -> SourceName -> s -> Either ParseError aparse p = runP p () what's the significance of `Identity t'? (`t' isn't used anywhere.) Thanks, -db ___ H

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