Re: [Haskell-cafe] Long pauses / idle time in a Haskell TCP server
Thanks for the tip Jamie! Setting NODELAY on the *client* resolved the problem; setting it on the server (both sockets) didn't make a difference. I'll see if I can figure out more about how this was going wrong - I did check the network traffic and the delay was at the server. But now I have a good setup to work with further. I did have your code from github, but from a while back, not long after you posted 0.2.2 to Hackage. I tinkered it a fair amount - stuff like where queues and worker threads are used, there are lots of options with that, especially given that thread creation is cheap so one doesn't necessarily need to use thread pools like in some other languages. Now I can play with those variations without distraction from long pauses. And I'll grab your latest from github and try that out. Thanks! Alex On Mon, Oct 8, 2012 at 6:41 PM, Jamie Turner ja...@bu.mp wrote: I'm seeing long pauses in a server based on the 'scalable-server' package from Hackage, version 0.2.2 [1]. It normally performs very well, about 100-150 micro-secs client latency over the loopback interface, but a fair number of requests are much slower, 38-40 milli-secs, making the mean latency and throughput quite bad. Hi Alex--author of scalable-server here. 38ms sounds like Nagle's algorithm. (http://en.wikipedia.org/wiki/Nagle's_algorithm) In short, the socket is waiting on sending a small amount of data to see if the application wants to send more data. If so, the kernel can repack the data together so that it all can be switched in one TCP packet. You need to set NoDelay (TCP_NODELAY) if you want to disable this behavior; scalable-server doesn't currently have a flag to configure this, but I'm open to pull requests! (Also, are you using hackage scalable-server, or the new scalable server based on conduit on github? I'd recommend switching to the github version if not. A few key bugs exist in the older implementation.) - Jamie ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Type of scramblings
I am reading through Oleg's Eliminating translucent existentials[1]. [1]: http://okmij.org/ftp/Computation/Existentials.html#eliminating-translucent He draws a distinction between forall a . [a] - [a] and forall a . [a]^n - [a] as types of scramblings. This is something I'm struggling to understand. First of all, I think here we're talking about total functions, otherwise there's no point in introducing dependent types. There are of course more total functions of type `[a]^n - [a]` than of type `[a] - [a]`, in the sense that any term of the latter type can be assigned the former type. But, on the other hand, any total function `f :: [a]^n - [a]` has an equivalent total function g :: [a] - [a] g xs | length xs == n = f xs | otherwise = xs (The condition `length xs == n` can be replaced by a similar condition that also works for infinite lists.) The functions `f` and `g` are equivalent in the sense that for any list `xs` of length `n` `f xs === g xs`. Thus, even though it seems that we allow more total functions by replacing `[a]` with `[a]^n`, that doesn't buy us any additional expressiveness. What am I missing? Roman ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANN: cabal-install-1.16.0 (and Cabal-1.16.0.1)
Johan Tibell johan.tib...@gmail.com writes: I'll make a bugfix release for cabal-install and Cabal in a few days to include fixes to issues people found so far. If everyone who had some problem related to the latest release could please post it here so I can make sure that we include a fix for them. If you've already reported it elsewhere, please bring it up here anyway to make sure I don't miss it. btw, what about Cabal being agnostic to some recent GHC language extensions, i.e.: https://github.com/haskell/cabal/issues/1050 is that one eligible for a point release? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] 64-bit vs 32-bit haskell platform on Mac: misleading notice on Platform website?
I've filed a bug report: http://hackage.haskell.org/trac/ghc/ticket/7314 My only problem is that I don't have OS X 10.8 installed on my machine. I'm running OS X 10.6, and am not inclined to upgrade. So providing feedback on the questions related to the bug report will be hard and/or take some time. -- Christiaan On Oct 8, 2012, at 4:25 PM, Johan Tibell wrote: Could you please file a bug report at: http://hackage.haskell.org/trac/ghc/ Thanks! ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] problem with cabal-install-1.16.0 and Cabal-1.16.0.1 on Haskell Platform for OS X
Hi, New Haskell user here. I have the latest Haskell Platform 2012.2.0.0 for Mac OS X, 64 bit installed. I have not installed any additional packages. Believe me, the Prelude hurts enough. Anyways, seeing the big update to cabal, I decided to install it and did a: cabal install cabal-install-1.16.0 Cabal-1.16.0.1 ...per the announcement. The installation seemingly went well (log attached) but I'm left with a symlink farm that's still pointing at the old version. NB: I did the installation in my own account (ddp), not via sudo which looks like what was probably expected given the ownerships I do see. Here's what I'm left with: % which cabal /usr/bin/cabal % ls -la /usr/bin/cabal lrwxr-xr-x 1 root wheel - 26 Oct 8 16:42 /usr/bin/cabal - /Library/Haskell/bin/cabal % ls -la /Library/Haskell/bin/cabal* lrwxr-xr-x 1 ddp wheel - 10 Oct 8 16:42 /Library/Haskell/bin/cabal - cabal.wrap lrwxr-xr-x 1 ddp wheel - 37 Oct 8 16:42 /Library/Haskell/bin/cabal.real - ../lib/cabal-install-0.14.0/bin/cabal -rwxr-xr-x 1 root admin - 4197 May 27 12:37 /Library/Haskell/bin/cabal.wrap I find that it actually installed itself here: % ls -la ~/Library/Haskell/bin/cabal* lrwxr-xr-x 1 ddp staff - 47 Oct 8 20:45 /Users/ddp/Library/Haskell/bin/cabal - ../ghc-7.4.1/lib/cabal-install-1.16.0/bin/cabal So I guess my questions are: 1) did I miss some step along the way? 2) what's the correct way to fix this? Just change the cabal.real symlink to point to where it actually is? 3) which, if any, directories should I have in my PATH in general: /Library/Haskell/bin, ~/Library/Haskell/bin, neither or both? Thanks, Derrell Installation log: fluffy512% cabal --version cabal-install version 0.14.0 using version 1.14.0 of the Cabal library fluffy513% cabal update Downloading the latest package list from hackage.haskell.org Note: there is a new version of cabal-install available. To upgrade, run: cabal install cabal-install fluffy514% cabal install cabal-install-1.16.0 Cabal-1.16.0.1 Resolving dependencies... [ 1 of 65] Compiling Distribution.Compat.Exception ( /var/folders/sm/f2yb5sp11490bcy5k6t46v20gn/T/Cabal-1.16.0.1-48304/Cabal-1.16.0.1/Distribution/Compat/Exception.hs, /var/folders/sm/f2yb5sp11490bcy5k6t46v20gn/T/Cabal-1.16.0.1-48304/Cabal-1.16.0.1/dist/setup/Distribution/Compat/Exception.o ) [ 2 of 65] Compiling Distribution.Compat.TempFile ( /var/folders/sm/f2yb5sp11490bcy5k6t46v20gn/T/Cabal-1.16.0.1-48304/Cabal-1.16.0.1/Distribution/Compat/TempFile.hs, /var/folders/sm/f2yb5sp11490bcy5k6t46v20gn/T/Cabal-1.16.0.1-48304/Cabal-1.16.0.1/dist/setup/Distribution/Compat/TempFile.o ) [ 3 of 65] Compiling Distribution.Compat.CopyFile ( /var/folders/sm/f2yb5sp11490bcy5k6t46v20gn/T/Cabal-1.16.0.1-48304/Cabal-1.16.0.1/Distribution/Compat/CopyFile.hs, /var/folders/sm/f2yb5sp11490bcy5k6t46v20gn/T/Cabal-1.16.0.1-48304/Cabal-1.16.0.1/dist/setup/Distribution/Compat/CopyFile.o ) [ 4 of 65] Compiling Distribution.GetOpt ( /var/folders/sm/f2yb5sp11490bcy5k6t46v20gn/T/Cabal-1.16.0.1-48304/Cabal-1.16.0.1/Distribution/GetOpt.hs, /var/folders/sm/f2yb5sp11490bcy5k6t46v20gn/T/Cabal-1.16.0.1-48304/Cabal-1.16.0.1/dist/setup/Distribution/GetOpt.o ) [ 5 of 65] Compiling Distribution.Compat.ReadP ( /var/folders/sm/f2yb5sp11490bcy5k6t46v20gn/T/Cabal-1.16.0.1-48304/Cabal-1.16.0.1/Distribution/Compat/ReadP.hs, /var/folders/sm/f2yb5sp11490bcy5k6t46v20gn/T/Cabal-1.16.0.1-48304/Cabal-1.16.0.1/dist/setup/Distribution/Compat/ReadP.o ) [ 6 of 65] Compiling Distribution.Text ( /var/folders/sm/f2yb5sp11490bcy5k6t46v20gn/T/Cabal-1.16.0.1-48304/Cabal-1.16.0.1/Distribution/Text.hs, /var/folders/sm/f2yb5sp11490bcy5k6t46v20gn/T/Cabal-1.16.0.1-48304/Cabal-1.16.0.1/dist/setup/Distribution/Text.o ) [ 7 of 65] Compiling Distribution.Version ( /var/folders/sm/f2yb5sp11490bcy5k6t46v20gn/T/Cabal-1.16.0.1-48304/Cabal-1.16.0.1/Distribution/Version.hs, /var/folders/sm/f2yb5sp11490bcy5k6t46v20gn/T/Cabal-1.16.0.1-48304/Cabal-1.16.0.1/dist/setup/Distribution/Version.o ) [ 8 of 65] Compiling Language.Haskell.Extension ( /var/folders/sm/f2yb5sp11490bcy5k6t46v20gn/T/Cabal-1.16.0.1-48304/Cabal-1.16.0.1/Language/Haskell/Extension.hs, /var/folders/sm/f2yb5sp11490bcy5k6t46v20gn/T/Cabal-1.16.0.1-48304/Cabal-1.16.0.1/dist/setup/Language/Haskell/Extension.o ) [ 9 of 65] Compiling Distribution.TestSuite ( /var/folders/sm/f2yb5sp11490bcy5k6t46v20gn/T/Cabal-1.16.0.1-48304/Cabal-1.16.0.1/Distribution/TestSuite.hs, /var/folders/sm/f2yb5sp11490bcy5k6t46v20gn/T/Cabal-1.16.0.1-48304/Cabal-1.16.0.1/dist/setup/Distribution/TestSuite.o ) [10 of 65] Compiling Distribution.System ( /var/folders/sm/f2yb5sp11490bcy5k6t46v20gn/T/Cabal-1.16.0.1-48304/Cabal-1.16.0.1/Distribution/System.hs, /var/folders/sm/f2yb5sp11490bcy5k6t46v20gn/T/Cabal-1.16.0.1-48304/Cabal-1.16.0.1/dist/setup/Distribution/System.o ) [11 of 65] Compiling
Re: [Haskell-cafe] problem with cabal-install-1.16.0 and Cabal-1.16.0.1 on Haskell Platform for OS X
Hi, Thanks for the detailed problem description. I've CCed Mark Lentczner, who designed the directory layout for the Haskell Platform on OS X. Hopefully he'll be able to tell you what to do. On Tue, Oct 9, 2012 at 8:31 AM, Derrell Piper d...@electric-loft.org wrote: Hi, New Haskell user here. I have the latest Haskell Platform 2012.2.0.0 for Mac OS X, 64 bit installed. I have not installed any additional packages. Believe me, the Prelude hurts enough. Anyways, seeing the big update to cabal, I decided to install it and did a: cabal install cabal-install-1.16.0 Cabal-1.16.0.1 ...per the announcement. The installation seemingly went well (log attached) but I'm left with a symlink farm that's still pointing at the old version. NB: I did the installation in my own account (ddp), not via sudo which looks like what was probably expected given the ownerships I do see. Here's what I'm left with: % which cabal /usr/bin/cabal % ls -la /usr/bin/cabal lrwxr-xr-x 1 root wheel - 26 Oct 8 16:42 /usr/bin/cabal - /Library/Haskell/bin/cabal % ls -la /Library/Haskell/bin/cabal* lrwxr-xr-x 1 ddp wheel - 10 Oct 8 16:42 /Library/Haskell/bin/cabal - cabal.wrap lrwxr-xr-x 1 ddp wheel - 37 Oct 8 16:42 /Library/Haskell/bin/cabal.real - ../lib/cabal-install-0.14.0/bin/cabal -rwxr-xr-x 1 root admin - 4197 May 27 12:37 /Library/Haskell/bin/cabal.wrap I find that it actually installed itself here: % ls -la ~/Library/Haskell/bin/cabal* lrwxr-xr-x 1 ddp staff - 47 Oct 8 20:45 /Users/ddp/Library/Haskell/bin/cabal - ../ghc-7.4.1/lib/cabal-install-1.16.0/bin/cabal So I guess my questions are: 1) did I miss some step along the way? 2) what's the correct way to fix this? Just change the cabal.real symlink to point to where it actually is? 3) which, if any, directories should I have in my PATH in general: /Library/Haskell/bin, ~/Library/Haskell/bin, neither or both? Thanks, Derrell Installation log: fluffy512% cabal --version cabal-install version 0.14.0 using version 1.14.0 of the Cabal library fluffy513% cabal update Downloading the latest package list from hackage.haskell.org Note: there is a new version of cabal-install available. To upgrade, run: cabal install cabal-install fluffy514% cabal install cabal-install-1.16.0 Cabal-1.16.0.1 Resolving dependencies... [ 1 of 65] Compiling Distribution.Compat.Exception ( /var/folders/sm/f2yb5sp11490bcy5k6t46v20gn/T/Cabal-1.16.0.1-48304/Cabal-1.16.0.1/Distribution/Compat/Exception.hs, /var/folders/sm/f2yb5sp11490bcy5k6t46v20gn/T/Cabal-1.16.0.1-48304/Cabal-1.16.0.1/dist/setup/Distribution/Compat/Exception.o ) [ 2 of 65] Compiling Distribution.Compat.TempFile ( /var/folders/sm/f2yb5sp11490bcy5k6t46v20gn/T/Cabal-1.16.0.1-48304/Cabal-1.16.0.1/Distribution/Compat/TempFile.hs, /var/folders/sm/f2yb5sp11490bcy5k6t46v20gn/T/Cabal-1.16.0.1-48304/Cabal-1.16.0.1/dist/setup/Distribution/Compat/TempFile.o ) [ 3 of 65] Compiling Distribution.Compat.CopyFile ( /var/folders/sm/f2yb5sp11490bcy5k6t46v20gn/T/Cabal-1.16.0.1-48304/Cabal-1.16.0.1/Distribution/Compat/CopyFile.hs, /var/folders/sm/f2yb5sp11490bcy5k6t46v20gn/T/Cabal-1.16.0.1-48304/Cabal-1.16.0.1/dist/setup/Distribution/Compat/CopyFile.o ) [ 4 of 65] Compiling Distribution.GetOpt ( /var/folders/sm/f2yb5sp11490bcy5k6t46v20gn/T/Cabal-1.16.0.1-48304/Cabal-1.16.0.1/Distribution/GetOpt.hs, /var/folders/sm/f2yb5sp11490bcy5k6t46v20gn/T/Cabal-1.16.0.1-48304/Cabal-1.16.0.1/dist/setup/Distribution/GetOpt.o ) [ 5 of 65] Compiling Distribution.Compat.ReadP ( /var/folders/sm/f2yb5sp11490bcy5k6t46v20gn/T/Cabal-1.16.0.1-48304/Cabal-1.16.0.1/Distribution/Compat/ReadP.hs, /var/folders/sm/f2yb5sp11490bcy5k6t46v20gn/T/Cabal-1.16.0.1-48304/Cabal-1.16.0.1/dist/setup/Distribution/Compat/ReadP.o ) [ 6 of 65] Compiling Distribution.Text ( /var/folders/sm/f2yb5sp11490bcy5k6t46v20gn/T/Cabal-1.16.0.1-48304/Cabal-1.16.0.1/Distribution/Text.hs, /var/folders/sm/f2yb5sp11490bcy5k6t46v20gn/T/Cabal-1.16.0.1-48304/Cabal-1.16.0.1/dist/setup/Distribution/Text.o ) [ 7 of 65] Compiling Distribution.Version ( /var/folders/sm/f2yb5sp11490bcy5k6t46v20gn/T/Cabal-1.16.0.1-48304/Cabal-1.16.0.1/Distribution/Version.hs, /var/folders/sm/f2yb5sp11490bcy5k6t46v20gn/T/Cabal-1.16.0.1-48304/Cabal-1.16.0.1/dist/setup/Distribution/Version.o ) [ 8 of 65] Compiling Language.Haskell.Extension ( /var/folders/sm/f2yb5sp11490bcy5k6t46v20gn/T/Cabal-1.16.0.1-48304/Cabal-1.16.0.1/Language/Haskell/Extension.hs, /var/folders/sm/f2yb5sp11490bcy5k6t46v20gn/T/Cabal-1.16.0.1-48304/Cabal-1.16.0.1/dist/setup/Language/Haskell/Extension.o ) [ 9 of 65] Compiling Distribution.TestSuite ( /var/folders/sm/f2yb5sp11490bcy5k6t46v20gn/T/Cabal-1.16.0.1-48304/Cabal-1.16.0.1/Distribution/TestSuite.hs,
Re: [Haskell-cafe] Ordering of BigFloats in numbers-3000.0.0.0
On Sun, Oct 7, 2012 at 8:00 PM, Michael Orlitzky mich...@orlitzky.com wrote: I'm trying to use, http://hackage.haskell.org/package/numbers-3000.0.0.0 to get better precision for free out of some numerical code. I ran into an issue pretty quickly, though. In Data.Number.BigFloat, we have, data BigFloat e = BF (Fixed e) Integer deriving (Eq, Ord) and the derived Ord is obviously incorrect: Prelude Data.Number.BigFloat let x = 0.1 :: BigFloat Prec50 Prelude Data.Number.BigFloat let y = 0.02 :: BigFloat Prec50 Prelude Data.Number.BigFloat x y True That's pretty strange since the derived Ord should be the same as Fixed Ord, which itself is just a newtype over Rational (and 1%10 2%100 == False), did you try to convert those BigFloat back to Rational to see if they're still correct ? That may be worse than a misbehaving Ord instance. -- Jedaï ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Ordering of BigFloats in numbers-3000.0.0.0
On 10/09/2012 12:29 PM, Chaddaï Fouché wrote: On Sun, Oct 7, 2012 at 8:00 PM, Michael Orlitzky mich...@orlitzky.com wrote: I'm trying to use, http://hackage.haskell.org/package/numbers-3000.0.0.0 to get better precision for free out of some numerical code. I ran into an issue pretty quickly, though. In Data.Number.BigFloat, we have, data BigFloat e = BF (Fixed e) Integer deriving (Eq, Ord) and the derived Ord is obviously incorrect: Prelude Data.Number.BigFloat let x = 0.1 :: BigFloat Prec50 Prelude Data.Number.BigFloat let y = 0.02 :: BigFloat Prec50 Prelude Data.Number.BigFloat x y True That's pretty strange since the derived Ord should be the same as Fixed Ord, which itself is just a newtype over Rational (and 1%10 2%100 == False), did you try to convert those BigFloat back to Rational to see if they're still correct ? That may be worse than a misbehaving Ord instance. The BigFloat constructor doesn't do what you think it does... I chose a bad spot to snip the comments: -- This representation is stupid, two Integers makes more sense, -- but is more work. -- | Floating point number where the precision is determined by the -- type /e/. data BigFloat e = BF (Fixed e) Integer deriving (Eq) If it was two Integers, I think it would be more clear that this is what will happen: *Data.Number.BigFloat let x = 0.1 :: BigFloat Prec50 *Data.Number.BigFloat let y = 0.02 :: BigFloat Prec50 *Data.Number.BigFloat let BF m1 e1 = x *Data.Number.BigFloat let BF m2 e2 = y *Data.Number.BigFloat (m1,e1) (1.00,-1) *Data.Number.BigFloat (m2,e2) (2.00,-2) The fast way to compare them would be to check the mantissa/exponent directly, but toRational works just fine. I made a pull request yesterday that compares them as rationals. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] total Data.Map.! function
Hi Joachim, On Wed, 5 Oct 2012, Joachim Breitner wrote: On Wed, 3 Oct 2012, Henning Thielemann wrote: I wondered whether there is a brilliant typing technique that makes Data.Map.! a total function. That is, is it possible to give (!) a type, such that m!k expects a proof that the key k is actually present in the dictionary m? How can I provide the proof that k is in m? Same question for 'lab' (import Data.Graph.Inductive(lab)). That is, can there be a totalLab, with (totalLab gr = fromJust . lab gr) that expects a proof that the node Id is actually contained in a graph? I think it is possible to do this using the same trick that ST is using, i.e. rank 2 types. The problem is that this code is likely to be unwieldy to use, as the variable needs to change with every change to the map – but I guess if you create your map once and then use it in various places without modification, this can actually work. Thank you for your detailed answer! I thought about such a tagging method but was missing your idea of updating tags of existing keys in order to reflect the knowledge about newly added keys. Your solution will certainly work for the set of methods you have implemented. All of your methods extend the set of keys or preserve it. But what about deletion? The certificate that key k is contained in a Map must be invalidated by the deletion of k. How could I add this to your approach? Maybe I should track the operations applied to the keys of a map and provide algebraic simplifications, like so: insert :: Ord k = Tagged s k - v - Tagged m (Map k v) - Tagged (Insert s m) (Map k v) lookup :: Ord k = Tagged s k - Tagged (Insert s m) (Map k v) - v -- * example simplifications commuteInsert :: Tagged (Insert s0 (Insert s1 m)) (Map k v) - Tagged (Insert s1 (Insert s0 m)) (Map k v) simplifyInsertInsert :: Tagged (Insert s (Insert s m)) (Map k v) - Tagged (Insert s m) (Map k v) simplifyInsertDelete :: Tagged (Insert s (Delete s m)) (Map k v) - Tagged (Insert s m) (Map k v) simplifyDeleteInsert :: Tagged (Delete s (Insert s m)) (Map k v) - Tagged (Delete s m) (Map k v) example = lookup k0 $ commuteInsert $ insert k1 for $ insert k0 bar m I also thought about something like the exceptions trick. That is, a context like (ContainsKeyA k, ContainsKeyB k) = Map k x might tell that certain keys are in the Map. However, this would not only mean that I need a type class for every insertion, it would also not work reliably for deletion. If keyA = keyB, then deletion of keyA must also remove the ContainsKeyB constraint. :-( ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] OpenGL library will not load into GHCi 7.6.1 on Win7 x86-64
This is a regression of some sort since the library operates fine within GHCi for previous versions of GHC. I don't know whether it is a problem with GHCi, the OpenGL library, or some third party. This is the error encountered when a module that uses OpenGL tries to load: Prelude Main main Loading package OpenGLRaw-1.2.0.0 ... linking ... ghc.exe: unable to load package `OpenGLRaw-1.2.0.0' Prelude Main :q Leaving GHCi. interactive: C:\...\OpenGLRaw-1.2.0.0\ghc-7.6.1\HSOpenGLRaw-1.2.0.0.o: unknown symbol `__imp_wglGetProcAddress' I have very little of an idea of what's going on here. It would be rather painful to debug this myself so any insight is appreciated. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] ANN: New York Haskell Users Group -- First Meeting on Wed., Nov 14.
The (arguably) greatest city in the U.S. now (finally) has a users group for (unarguably) the greatest programming language anywhere. We're very happy to announce the inaugural meeting of the New York Haskell Users Group. We intend this group to be welcoming to new developers, but with enough substance to keep old Haskell hands interested and amused. If you're in the area but can't make it, you can join the meetup regardless at http://www.meetup.com/NY-Haskell/ to stay informed of future events. We plan to have a mix of talks and experience reports at all levels, so if you will be passing through town and might have something to say, let us know! Two Haskell Talks: Practical Data Processing With Haskell _and_ Putting Cloud Haskell to Work Wednesday, November 14, 2012 7:00 PM To 9:00 PM Pivotal Labs, 841 Broadway New York, NY RSVP: http://www.meetup.com/NY-Haskell/ We're kicking off the New York Haskell Users Group with two great talks, one for people just getting started and one for those with some experience already. Both should be accessible and enjoyable no matter how much (or little) you already know. Food and refreshments will be provided, courtesy of the generosity of Pivotal Labs, and after the talks, we're planning to keep the discussion going over food and drink at a nearby establishment. 7pm - Practical Data Processing With Haskell: Ozgun Ataman will give an introductory talk on Haskell, diving right in with how you can start using Haskell for practical data manipulation tasks today. You'll be introduced to a typical setup for Haskell development and given a demonstration of how a common data format (CSV, JSON, etc.) can be parsed, processed and finally output using Haskell. The talk will include a small actual Haskell program to be modified live and some commentary around using Haskell in practical applications. 8pm - Putting Cloud Haskell to Work for Distributed Computing: Gershom Bazerman will give an overview of the new distributed-process library that implements Cloud Haskell, providing computation across heterogeneous nodes through a message passing interface. He will discuss what this new tool provides out of the box, and what you'll have to bring to the table. The talk will include some code samples using the new library, as well as some experience about what it's like to use Haskell for distributed computing in the real world. Speaker Biographies: Ozgun Ataman is the founder of Soostone, a managment consulting and analytics company built on Haskell. He is the author of many open-source Haskell libraries, and is a contributor to the Snap web framework. Gershom Bazerman is a developer at SP Capital IQ. He is most well known in the Haskell community as the author of the JMacro library for programmatic generation of JavaScript, and for one well-received April fools joke. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] OpenGL library will not load into GHCi 7.6.1 on Win7 x86-64
On Tue, Oct 9, 2012 at 1:55 PM, Dan Haraj devha...@gmail.com wrote: This is a regression of some sort since the library operates fine within GHCi for previous versions of GHC. I don't know whether it is a problem with GHCi, the OpenGL library, or some third party. This is the error encountered when a module that uses OpenGL tries to load: Prelude Main main Loading package OpenGLRaw-1.2.0.0 ... linking ... ghc.exe: unable to load package `OpenGLRaw-1.2.0.0' Prelude Main :q Leaving GHCi. interactive: C:\...\OpenGLRaw-1.2.0.0\ghc-7.6.1\HSOpenGLRaw-1.2.0.0.o: unknown symbol `__imp_wglGetProcAddress' I have very little of an idea of what's going on here. It would be rather painful to debug this myself so any insight is appreciated. I don't know the solution or the culprit, but normally that symbol is defined in opengl32.lib/dll and the OpenGLRaw cabal file mentions it as an extra library. Jason ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] object file cannot be loaded.
Seems like an issue with fedora17's ld. I altered it with ld.gold. Working. On Tue, Oct 9, 2012 at 7:33 AM, Magicloud Magiclouds magicloud.magiclo...@gmail.com wrote: Could anyone help me on this? On Sun, Oct 7, 2012 at 10:34 AM, Magicloud Magiclouds magicloud.magiclo...@gmail.com wrote: There is none On Sun, Oct 7, 2012 at 4:27 AM, Thomas Schilling nomin...@googlemail.com wrote: Does `ghc-pkg check` report any issues? On 6 October 2012 15:24, Magicloud Magiclouds magicloud.magiclo...@gmail.com wrote: Hi, I am installing postgres hackage (cannot remember the exact name right now). When it compiling the template haskell part I got the following error message. I tried to clear all user space hackages. Not helping. Loading package text-0.11.2.3 ... linking ... ghc: /home/magicloud/.cabal/lib/text-0.11.2.3/ghc-7.6.1/HStext-0.11.2.3.o: unknown symbol `bytestringzm0zi10zi0zi1_DataziByteStringziInternal_PS_con_info' ghc: unable to load package `text-0.11.2.3' -- 竹密岂妨流水过 山高哪阻野云飞 And for G+, please use magiclouds#gmail.com. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- Push the envelope. Watch it bend. -- 竹密岂妨流水过 山高哪阻野云飞 And for G+, please use magiclouds#gmail.com. -- 竹密岂妨流水过 山高哪阻野云飞 And for G+, please use magiclouds#gmail.com. -- 竹密岂妨流水过 山高哪阻野云飞 And for G+, please use magiclouds#gmail.com. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Ordering of BigFloats in numbers-3000.0.0.0
you should probably file a ticket on the DanBurton repo if he's the one doing the uploading :-) On Tue, Oct 9, 2012 at 12:55 PM, Michael Orlitzky mich...@orlitzky.comwrote: On 10/09/2012 12:29 PM, Chaddaï Fouché wrote: On Sun, Oct 7, 2012 at 8:00 PM, Michael Orlitzky mich...@orlitzky.com wrote: I'm trying to use, http://hackage.haskell.org/package/numbers-3000.0.0.0 to get better precision for free out of some numerical code. I ran into an issue pretty quickly, though. In Data.Number.BigFloat, we have, data BigFloat e = BF (Fixed e) Integer deriving (Eq, Ord) and the derived Ord is obviously incorrect: Prelude Data.Number.BigFloat let x = 0.1 :: BigFloat Prec50 Prelude Data.Number.BigFloat let y = 0.02 :: BigFloat Prec50 Prelude Data.Number.BigFloat x y True That's pretty strange since the derived Ord should be the same as Fixed Ord, which itself is just a newtype over Rational (and 1%10 2%100 == False), did you try to convert those BigFloat back to Rational to see if they're still correct ? That may be worse than a misbehaving Ord instance. The BigFloat constructor doesn't do what you think it does... I chose a bad spot to snip the comments: -- This representation is stupid, two Integers makes more sense, -- but is more work. -- | Floating point number where the precision is determined by the -- type /e/. data BigFloat e = BF (Fixed e) Integer deriving (Eq) If it was two Integers, I think it would be more clear that this is what will happen: *Data.Number.BigFloat let x = 0.1 :: BigFloat Prec50 *Data.Number.BigFloat let y = 0.02 :: BigFloat Prec50 *Data.Number.BigFloat let BF m1 e1 = x *Data.Number.BigFloat let BF m2 e2 = y *Data.Number.BigFloat (m1,e1) (1.00,-1) *Data.Number.BigFloat (m2,e2) (2.00,-2) The fast way to compare them would be to check the mantissa/exponent directly, but toRational works just fine. I made a pull request yesterday that compares them as rationals. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
