[Haskell-cafe] Text.Regex Segfault
I bumped into a segmentation fault in the regex library today and thought I'd warn others in case similar behavior is observed: Prelude :m Text.Regex Prelude Text.Regex map read (splitRegex (mkRegex \\|) 0|1|2|4) :: [Int] Loading package syb ... linking ... done. Loading package array-0.2.0.0 ... linking ... done. Loading package bytestring-0.9.1.4 ... linking ... done. Loading package regex-base-0.72.0.2 ... linking ... done. Loading package regex-posix-0.72.0.3 ... linking ... done. Loading package regex-compat-0.71.0.1 ... linking ... done. [0,1,2,4] Prelude Text.Regex Segmentation fault Regards, Duane ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] FRP for game programming / artifical life simulation
This is really good stuff, Luke. I am interested in learning more,
especially in seeing examples or actual game code that implement the
more common parts of a game. I build a game (silkworm) in Haskell
that was one of my first Haskell programs. The code was not pretty,
and I always felt there was a better way. It seems you are on to a
better way.
When you're ready, I'll be watching for the announcement ;)
Regards,
Duane Johnson
On Apr 21, 2010, at 6:39 PM, Luke Palmer wrote:
On Wed, Apr 21, 2010 at 4:47 PM, Ben Christy ben.chri...@gmail.com
wrote:
I have an interest in both game programming and artificial life. I
have
recently stumbled on Haskell and would like to take a stab at
programming a
simple game using FRP such as YAMPA or Reactive but I am stuck. I
am not
certain which one I should choose. It seems that Reactive is more
active but
is it suitable for game programming. Also has anyone attempted to
implement
neural networks using FRP if so again which of these two approaches
to FRP
would you suggest?
I am in the process of writing a game using FRP. I haven't followed
reactive in a while, but last I checked it had some rather annoying
issues, such as joinE (monad join on events) not working and an open
space leak. So we are using a Yampa-like approach, but not
specifically Yampa. However most of the game logic is *not* in AFRP
(arrowized FRP) style, it is just there to give a nice foundation
and top level game loop, playing much the same role as IO does in many
Haskell programs (but it is implemented purely!).
The workhorse of our game has so far been generalized differentials.
While not entirely rigorous, they have provided a very nice framework
in which to express our thoughts and designs, and are very good at
highly dynamic situations which appear in games. For example, with
arrows it is painful to maintain a list of moving actors such that can
be added and removed. With differentials this is quite natural.
I haven't published the differential library yet, I am waiting until
we have used them enough to discover essential techniques and find a
nice bases for primitives. But I will give a sketch here. Let the
types be your guide, as I am implementing from memory without a
compiler :-P
import qualified Data.Accessor.Basic as Acc
import Data.VectorSpace
import Control.Comonad
A differential is implemented as a function that takes a timestep and
returns an update function. Don't expose the D constructor; step is
okay to expose, it's kind of a generalized linear approximation.
newtype D a = D { step :: Double - a - a }
instance Monoid (D a) where
mempty = D (const id)
mappend da db = D (\dt - step da dt . step db dt)
Given a differential for a component of a value, we can construct a
differential for that value.
accessor :: Acc.T s a - D a - D s
accessor acc da = D (Acc.modify acc . step da)
Given a differential for each component of a tuple, we can find the
differential for the tuple.
product :: D a - D b - D (a, b)
product da db = D (\dt (x,y) - (step da dt x, step db dt y))
A differential can depend on the current value.
dependent :: (a - D a) - D a
dependent f = D (\dt x - step (f x) dt x)
Vectors can be treated directly as differentials over themselves.
vector :: (VectorSpace v, Scalar v ~ Double) = v - D v
vector v = D (\dt x - x ^+^ dt *^ v)
Impulses allow non-continuous burst changes, such as adding/removing
an element from a list of actors. This is the only function that bugs
me. Incorrectly using it you can determine the framerate, which is
supposed be hidden. But if used correctly; i.e. only trigger them on
passing conditions, they can be quite handy. But my eyes and ears are
open for alternatives.
impulse :: (a - a) - D a
impulse f = D (const f)
If we can can find the differential for an element of some comonad
given its context, we can find the differential for the whole
structure. (Our game world is a comonad, that's why this is in
here)
comonad :: (Comonad w) = (w a - D a) - D (w a)
comonad f = D (\dt - let h w = step (f w) dt (extract w) in extend
h)
I add new primitives at the drop of a hat. I would like to find a nice
combinator basis, but as yet, one hasn't jumped out at me. It might
require some tweaking of the concept.
The arrow we are using is implemented in terms of differentials:
data Continuous a b = forall s. Continuous s (s - a - (b, D s))
instance Category Continuous where
id = Continuous () (\() x - (x, mempty))
Continuous sg0 g . Continuous sf0 f = MkC (sg0,sf0) $ \(sg,sf) x
-
let !(y, df) = f sf x -- mind the strict patterns
!(z, dg) = g sg y in
(z, product dg df)
Exercise: implement the Arrow and ArrowLoop instances.
And here is where it comes together. Integration over generalized
differentials is a continuous arrow:
integral :: Continuous (D a) a
integral a0 = Continuous a0 (,)
So our game loop looks something like
Re: [Haskell-cafe] ANNOUNCE: Agata-0.2.0
Wow, very cool! This is so helpful I'm surprised it isn't part of
QuickCheck. Why isn't it?
Regards,
Duane Johnson
On Apr 17, 2010, at 6:43 PM, Jonas Almström Duregård wrote:
{-#LANGUAGE TemplateHaskell #-}
import Test.QuickCheck
import Test.AgataTH
data X a b = X [Either a b] deriving Show
data Y = Y deriving Show
data Z = Z deriving Show
$(agatath $ deriveall [''X,''Y,''Z])
main = sample (arbitrary :: Gen (X Y Z))
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[Haskell-cafe] How can I parameterize the Candidate?
Hello, How can I parameterize the type of the following data class so that any type can be a Candidate? type Candidate = String data Poll = Poll [Candidate] [Ballot] My initial thought was to simply put a type variable in place of Candidate, but that clearly won't work: data Poll = Poll [a] [Ballot] Not in scope: type variable `a' For context: I am building a voting library that addresses the issue of polarized American politics by implementing the Virtual Round Robin electoral method with a Maximum Majority Voting algorithm for breaking cycles. The beginnings of the library are available at http://github.com/canadaduane/votelib/blob/master/vote.hs What is a good approach to the parameterized type issue? Thank you, Duane Johnson ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] How can I parameterize the Candidate?
Ah, just a character away. Thank you. Duane On Mar 28, 2010, at 9:21 PM, Ivan Miljenovic wrote: On 29 March 2010 13:13, Duane Johnson duane.john...@gmail.com wrote: How can I parameterize the type of the following data class so that any type can be a Candidate? data Poll = Poll [Candidate] [Ballot] data Poll a = Poll [a] [Ballot] data Poll = Poll [a] [Ballot] So close... -- Ivan Lazar Miljenovic ivan.miljeno...@gmail.com IvanMiljenovic.wordpress.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Is anyone reading Pattern Calculus by Barry Jay?
Thanks Bernie, I've applied for membership in the forum. I'm grateful that technology can connect me with so distant but interesting a group! Duane On Dec 7, 2009, at 12:41 AM, Bernie Pope florbit...@gmail.com wrote: 2009/12/7 Duane Johnson duane.john...@gmail.com: I just bought a copy of Pattern Calculus [1] by Barry Jay and I would like to discuss the lambda- and pattern-calculus with anyone who is interested. Is there anyone else here who is reading the book and would like to discuss here (if it is appropriate) or take the discussion elsewhere? My knowledge of types has come primarily through reading this Haskell Cafe list, so I am by no means an expert. Just a tinkerer :) Regards, Duane Johnson [1] http://lambda-the-ultimate.org/node/3695 Hi Duane, The Melbourne FPU (functional programming union) is interested in topics like this, and some of us have a copy, or are about to get a copy of the book. http://groups.google.com.au/group/fpunion There's already a short thread on the topic - please feel free to sign up to the group. We welcome stimulating discussion. Cheers, Bernie. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Is anyone reading Pattern Calculus by Barry Jay?
I just bought a copy of Pattern Calculus [1] by Barry Jay and I would like to discuss the lambda- and pattern-calculus with anyone who is interested. Is there anyone else here who is reading the book and would like to discuss here (if it is appropriate) or take the discussion elsewhere? My knowledge of types has come primarily through reading this Haskell Cafe list, so I am by no means an expert. Just a tinkerer :) Regards, Duane Johnson [1] http://lambda-the-ultimate.org/node/3695___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] GLFW - Mac OS X
Yes, it seemed to work fine for me (this was about 2 months ago, however). I'm running Leopard (10.5.6). -- Duane On May 7, 2009, at 1:12 PM, Günther Schmidt wrote: Hi, has anybody recently install the GLFW package on Mac OS X? It won't install on my machine. Günther ___ 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
Re: [Haskell-cafe] Visualizing Typed Functions
No, this is a first-time draft that I made by hand using Inkscape. If we get to a point where a consistent set of visualizations makes sense, it would be rewarding to turn into code though. -- Duane On May 7, 2009, at 3:06 PM, John Van Enk wrote: Do you have code to generate these images from type signatures? If so I'd *love* to see it. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Visualizing Typed Functions
Thank you, that was very instructive! Tangible Values look very interesting. -- Duane On May 7, 2009, at 3:11 PM, Ahn, Ki Yung wrote: Duane Johnson wrote: With these functions visualized, one could make a kind of drag and drop interface for Haskell programming, although that isn't really my intention. I admit this is a little convoluted even for the purpose of visualization, but at least it's a starting place. Does anyone know of another system or better representation? You must to take a look at this: Tangible Functional Programming http://www.youtube.com/watch?v=faJ8N0giqzw And, a little bit off topic but cool stuff: Vacuum: visualize Haskell data structures live http://www.youtube.com/watch?v=X4-212uMgy8 @ It seems that we are getting pretty close to the point that youtube is getting to be a better reference than a paper, at least for practitioners. A lot of talks are on youtube :) ___ 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
Re: [Haskell-cafe] ANN: Silkworm game
So here's the thing to get it to run on Mac OS X, I have to build a SilkwormGame.app directory, with a Resources directory inside, along with a lot of other rubbish, just so that GLFW can create a Mac OS window that accepts mouse and keyboard input. This is the purpose of the Makefile--it uses a script borrowed from wxWindows to assemble all the parts. Obviously, this rigamarole is not necessary in Unix. But am I correct in assuming that there is no facility in Cabal that prepares a Mac OS app in this way? Any suggestions so that a cabal install will work for both Unix and Mac users? Here is what I get (using Don's Silkworm.cabal): ~/Documents/Duane/BYU Semesters/2009-Winter/Graphics/ Silkworm(master) $ cabal install Resolving dependencies... Configuring Silkworm-0.2... Preprocessing executables for Silkworm-0.2... Building Silkworm-0.2... [ 1 of 16] Compiling Silkworm.Action ( Silkworm/Action.hs, dist/ build/SilkwormGame/SilkwormGame-tmp/Silkworm/Action.o ) ... snip... [16 of 16] Compiling Main ( main.hs, dist/build/ SilkwormGame/SilkwormGame-tmp/Main.o ) Linking dist/build/SilkwormGame/SilkwormGame ... Installing executable(s) in /Users/duane/.cabal/bin ~/Silkworm(master) $ SilkwormGame Working in unbundled mode. You should build a .app wrapper for your Mac OS X applications. SilkwormGame: ~/Silkworm/background.png: openBinaryFile: does not exist (No such file or directory) Putting the binary files in the place it expects produces the same working in unbundled mode along with a window that will not capture ANY input from the mouse or keyboard. In fact, it won't even rise to the top of the window stack--it remains behind the terminal window. Thanks for you help, -- Duane On May 2, 2009, at 6:07 PM, Don Stewart wrote: Yes, it is quite fun. I think it should be using cabal's datadir from Paths_silkworm.hs to install (and find) the resources. Yell if you can't figure out how to do that. (xmonad has an example) -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANN: Silkworm game
I'm not too much of an expert in Haskell, but I did notice that building the game required keeping track of a lot of state information, which was not very intuitive in Haskell (although the OpenGL state info is rather intuitive). If I were to do it in Haskell again, I would try to learn more about FRP (Functional Reactive Programming) and see if that improves things in terms of state. Ruby is my favorite imperative language, so I would certainly recommend it for game development. It would likely be much easier in Ruby, but perhaps a little slower. My experience with Ruby on Rails has been that it is always a little slower than I wish it were :) -- Duane On May 3, 2009, at 4:48 PM, Daryoush Mehrtash wrote: I noticed that Chipmunk also has a Ruby interface. Do you have any pro/con of implementing the game in Ruby vs Haskell? Thanks, Daryoush On Sat, May 2, 2009 at 12:00 PM, Duane Johnson duane.john...@gmail.com wrote: Reprinted from my blog post [1]: === The semester is over, my final project was a success (at least in that I passed the class) and it’s time now to release the game I made for Graphics 455: Silkworm! This is my first full application in Haskell. The process has been an enlarging experience–I’ve come to really enjoy the mental work that goes into thinking about a program in a functional way. I highly recommend the challenge to other software engineers. Silkworm combines the Hipmunk binding to Chipmunk 2D Game Dynamics with OpenGL, and GLFW (an alternative to GLUT). It’s built to work on Mac OS X, but it uses cross-platform libraries so it should be fairly easy to port to other platforms. The source code is here [2] and below are some screenshots [1] -- Duane Johnson (canadaduane) === [1] http://blog.inquirylabs.com/2009/05/02/silkworm-game-written-in-haskell/ [2] http://inquirylabs.com/downloads/Silkworm.tgz___ 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
[Haskell-cafe] ANN: Silkworm game
Reprinted from my blog post [1]: === The semester is over, my final project was a success (at least in that I passed the class) and it’s time now to release the game I made for Graphics 455: Silkworm! This is my first full application in Haskell. The process has been an enlarging experience–I’ve come to really enjoy the mental work that goes into thinking about a program in a functional way. I highly recommend the challenge to other software engineers. Silkworm combines the Hipmunk binding to Chipmunk 2D Game Dynamics with OpenGL, and GLFW (an alternative to GLUT). It’s built to work on Mac OS X, but it uses cross-platform libraries so it should be fairly easy to port to other platforms. The source code is here [2] and below are some screenshots [1] -- Duane Johnson (canadaduane) === [1] http://blog.inquirylabs.com/2009/05/02/silkworm-game-written-in-haskell/ [2] http://inquirylabs.com/downloads/Silkworm.tgz___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANN: Silkworm game
Thanks, Felipe! Indeed, it was a wonderful surprise to see a 2D physics engine binding for Haskell. It made it possible for me to choose Haskell as my implementation language. I'm very grateful for that. I wish you luck (and time!) in implementing your ideas :) Regards, Duane On May 2, 2009, at 2:44 PM, Felipe Lessa wrote: Hi! On Sat, May 02, 2009 at 01:00:23PM -0600, Duane Johnson wrote: Silkworm combines the Hipmunk binding to Chipmunk 2D Game Dynamics with OpenGL, and GLFW (an alternative to GLUT). It's great to see Hipmunk being useful to someone :). I've written the binding to turn some of my ideas into code but I've never finished any of them. -- Felipe. ___ 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
Re: [Haskell-cafe] threadDelay granularity
The Hipmunk 2D physics engine comes with a playground app which includes the following function: -- | Advances the time. advanceTime :: IORef State - Double - KeyButtonState - IO Double advanceTime stateVar oldTime slowKey = do newTime - get time -- Advance simulation let slower = if slowKey == Press then slowdown else 1 mult = frameSteps / (framePeriod * slower) framesPassed = truncate $ mult * (newTime - oldTime) simulNewTime = oldTime + toEnum framesPassed / mult advanceSimulTime stateVar $ min maxSteps framesPassed -- Correlate with reality newTime' - get time let diff = newTime' - simulNewTime sleepTime = ((framePeriod * slower) - diff) / slower when (sleepTime 0) $ sleep sleepTime return simulNewTime I think the get time is provided by GLFW. -- Duane Johnson On Apr 7, 2009, at 9:25 AM, Ulrik Rasmussen wrote: On Tue, Apr 07, 2009 at 04:34:22PM +0200, Peter Verswyvelen wrote: Do you want to cap the rendering framerate at 60FPS or the animation framerate? Because when you use OpenGL and GLFW, you can just GLFW.swapInterval $= 1 to cap the rendering framerate at the refresh rate of your monitor or LCD screen (usually 60Hz) I just want to cap the rendering framerate. The game logic is running in other threads, and sends rendering information via a Chan to the renderer. I'm using GLUT, and have never heard of GLFW. However, that seems to be a better tool to get the job done. I'll check it out, thanks :). /Ulrik On Tue, Apr 7, 2009 at 1:41 PM, Ulrik Rasmussen hask...@utr.dk wrote: Hello. I am writing a simple game in Haskell as an exercise, and in the rendering loop I want to cap the framerate to 60fps. I had planned to do this with GHC.Conc.threadDelay, but looking at it's documentation, I discovered that it can only delay the thread in time spans that are multiples of 20ms: http://www.haskell.org/ghc/docs/6.4/html/libraries/base/Control.Concurrent.html I need a much finer granularity than that, so I wondered if it is possible to either get a higher resolution for threadDelay, or if there is an alternative to threadDelay? I noticed that the SDL library includes the function delay, which indeed works with a resolution down to one millisecond. However, since I'm using HOpenGL and GLUT, I think it would be a little overkill to depend on SDL just for this :). Thanks, Ulrik Rasmussen ___ 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 ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Linking hmatrix without LAPACK
Hi Alberto! Thanks for your informative reply. I looked in to the versions of liblapack on my system... it turns out there is indeed a liblapack.dylib that (apparently) comes with Mac OS X. How to tell ghc to link to that instead is still in question. I can run simple matrix operations in ghci as you suggest (in fact, runTests 20 succeeds wonderfully); however, I created the following simple module (test.hs) and it fails: module Main where import Numeric.LinearAlgebra.Tests main = do runTests 20 I tried plain --make, as well as the -dynamic flag, and then I tried the -L shell argument to point to the /usr/lib dir where the liblapack.dylib library is located: $ ghc --make test.hs -o test [1 of 1] Compiling Main ( test.hs, test.o ) Linking test ... ld: in /opt/local/lib/liblapack.a( ), not a valid archive member collect2: ld returned 1 exit status $ ghc --make -dynamic test.hs -o test Linking test ... ld: library not found for -lHShmatrix-0.5.0.1-ghc6.10.1 collect2: ld returned 1 exit status $ ghc --make -L/usr/lib test.hs -o test Linking test ... Undefined symbols: _zgemm_, referenced from: _multiplyC in libHShmatrix-0.5.0.1.a(lapack-aux.o) _zgesv_, referenced from: _linearSolveC_l in libHShmatrix-0.5.0.1.a(lapack-aux.o) _zpotrf_, referenced from: _chol_l_H in libHShmatrix-0.5.0.1.a(lapack-aux.o) _dpotrf_, referenced from: _chol_l_S in libHShmatrix-0.5.0.1.a(lapack-aux.o) _dgemm_, referenced from: _multiplyR in libHShmatrix-0.5.0.1.a(lapack-aux.o) _dgesv_, referenced from: _linearSolveR_l in libHShmatrix-0.5.0.1.a(lapack-aux.o) _zgetrf_, referenced from: _lu_l_C in libHShmatrix-0.5.0.1.a(lapack-aux.o) _zgetrs_, referenced from: _luS_l_C in libHShmatrix-0.5.0.1.a(lapack-aux.o) _dgetrf_, referenced from: _lu_l_R in libHShmatrix-0.5.0.1.a(lapack-aux.o) _dgetrs_, referenced from: _luS_l_R in libHShmatrix-0.5.0.1.a(lapack-aux.o) ld: symbol(s) not found collect2: ld returned 1 exit status I attempted to install hmatrix with the -faccelerate option, but when using ghc --make for the above test code, I received the same error messages noted previously. Is there a way to tell if the - faccelerate was acknowledged and that the alternate library was used? One more clue: I took a look at the directions found on the page at mit.edu/harold... it turns out I had installed atlas/lapack unnecessarily. That explains the mysterious not a valid archive member message. Nevertheless, I am still befuddled by the Undefined symbols above. ghc --make is still unable to figure out where the liblapack.dylib file is in spite of ghci's success. Any suggestions from here? Regards, Duane Johnson P.S. I'm CC'ing the Haskell Cafe so that our journey so far can be archived. On Apr 6, 2009, at 12:22 PM, Alberto Ruiz wrote: Hi Duane, I have seen your messages to Haskell Cafe but I am still thinking about the problem... :) Can you run simple matrix operations in ghci? $ ghci Prelude import Numeric.LinearAlgebra Prelude Numeric.LinearAlgebra let m = (22) [1..4 :: Double] (...Loading packages...) Prelude Numeric.LinearAlgebra m m (22) [ 7.0, 10.0 , 15.0, 22.0 ] If so, some version of blas/lapack can be found in your system, it is strange that ghc --make doesn't find them. Perhaps the problem is that dynamic libraries like liblapack.so are required instead of static ones like liblapack.a. (In ubuntu they are in the devel packages for blas/lapack.) I am not familiar with Mac OS, but if you can use the accelerate framework in your system you may try the -faccelerate configuration option for hmatrix: cabal install hmatrix -faccelerate See also the following page (steps 3-8). It explains how to install hmatrix on Mac OS (required for other project). http://mit.edu/harold/Public/easyVisionNotes.html Please let me know if any of these methods works for you. Thanks for your message, Alberto Duane Johnson wrote: Hi Alberto, I've been very happy with hmatrix as I've used it in ghci, and I should first thank you for making such an excellent package. I've had trouble when linking it using ghc --make on Mac OS (Leopard). Below are two messages I sent to the Haskell Cafe mailing list. Do you have any insight into either question: 1. How to link without atlas/lapack 2. What the not a valid archive member message means? Thank you! Duane Johnson Brigham Young University Provo, UT Begin forwarded message: From: Don Stewart d...@galois.com Date: April 5, 2009 11:48:38 PM MDT To: Duane Johnson duane.john...@gmail.com Subject: Re: [Haskell-cafe] Re: Linking hmatrix without LAPACK It would be best to contact the author of hmatrix directly. duane.johnson: On a related note, I've installed Atlas, and I get the following error when linking: Linking SilkwormGame ... ld: in /opt/local/lib/liblapack.a(), not a valid archive member collect2: ld
[Haskell-cafe] ghc --make unable to find dynamic library, but ghci can
Hi Haskellers, This is related to my previous message, Linking hmatrix without LAPACK. Apparently, ghc --make is not finding the lapack.dylib library where ghci is (dylib is Mac OS X specific) . For example, the following test module does NOT work when compiled with ghc --make: module Main where import Numeric.LinearAlgebra.Tests main = do runTests 20 But the following runs fine in ghci: $ ghci GHCi, version 6.10.1: http://www.haskell.org/ghc/ :? for help [...loading packages...] Prelude :m Numeric.LinearAlgebra.Tests Prelude Numeric.LinearAlgebra.Tests runTests 20 [...loading packages...] -- mult OK, passed 100 tests. OK, passed 100 tests. [...more tests pass...] Can anyone point me in the right direction? Thank you, Duane Johnson ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Linking hmatrix without LAPACK
FYI, the following solution worked on Mac OS X (Leopard): ghc -o SilkwormGame --make -framework Accelerate Main.hs The key addition is -framework Accelerate. Thus, on Mac OS X, it is only necessary to install the gls library via macports. Atlas/ LAPACK/BLAS etc. come with the operating system framework above. Also, I had to replace a DYLD_LIBRARY_PATH assignment in my .profile with DYLD_FALLBACK_LIBRARY_PATH: export DYLD_LIBRARY_PATH=/opt/local/lib:/usr/local/cuda/lib becomes: export DYLD_FALLBACK_LIBRARY_PATH=/opt/local/lib:/usr/local/cuda/lib The above change permitted me to use Apple's libraries by default, and my macports libraries as fallbacks. In particular, when I installed the atlas package via macports, it seems to have updated a key libjpeg.dylib file, thus causing other headaches. Using the fallback method above, the problems went away. Regards, Duane Johnson On Apr 6, 2009, at 1:51 PM, Duane Johnson wrote: Hi Alberto! Thanks for your informative reply. I looked in to the versions of liblapack on my system... it turns out there is indeed a liblapack.dylib that (apparently) comes with Mac OS X. How to tell ghc to link to that instead is still in question. I can run simple matrix operations in ghci as you suggest (in fact, runTests 20 succeeds wonderfully); however, I created the following simple module (test.hs) and it fails: module Main where import Numeric.LinearAlgebra.Tests main = do runTests 20 I tried plain --make, as well as the -dynamic flag, and then I tried the -L shell argument to point to the /usr/lib dir where the liblapack.dylib library is located: $ ghc --make test.hs -o test [1 of 1] Compiling Main ( test.hs, test.o ) Linking test ... ld: in /opt/local/lib/liblapack.a( ), not a valid archive member collect2: ld returned 1 exit status $ ghc --make -dynamic test.hs -o test Linking test ... ld: library not found for -lHShmatrix-0.5.0.1-ghc6.10.1 collect2: ld returned 1 exit status $ ghc --make -L/usr/lib test.hs -o test Linking test ... Undefined symbols: _zgemm_, referenced from: _multiplyC in libHShmatrix-0.5.0.1.a(lapack-aux.o) _zgesv_, referenced from: _linearSolveC_l in libHShmatrix-0.5.0.1.a(lapack-aux.o) _zpotrf_, referenced from: _chol_l_H in libHShmatrix-0.5.0.1.a(lapack-aux.o) _dpotrf_, referenced from: _chol_l_S in libHShmatrix-0.5.0.1.a(lapack-aux.o) _dgemm_, referenced from: _multiplyR in libHShmatrix-0.5.0.1.a(lapack-aux.o) _dgesv_, referenced from: _linearSolveR_l in libHShmatrix-0.5.0.1.a(lapack-aux.o) _zgetrf_, referenced from: _lu_l_C in libHShmatrix-0.5.0.1.a(lapack-aux.o) _zgetrs_, referenced from: _luS_l_C in libHShmatrix-0.5.0.1.a(lapack-aux.o) _dgetrf_, referenced from: _lu_l_R in libHShmatrix-0.5.0.1.a(lapack-aux.o) _dgetrs_, referenced from: _luS_l_R in libHShmatrix-0.5.0.1.a(lapack-aux.o) ld: symbol(s) not found collect2: ld returned 1 exit status I attempted to install hmatrix with the -faccelerate option, but when using ghc --make for the above test code, I received the same error messages noted previously. Is there a way to tell if the - faccelerate was acknowledged and that the alternate library was used? One more clue: I took a look at the directions found on the page at mit.edu/harold... it turns out I had installed atlas/lapack unnecessarily. That explains the mysterious not a valid archive member message. Nevertheless, I am still befuddled by the Undefined symbols above. ghc --make is still unable to figure out where the liblapack.dylib file is in spite of ghci's success. Any suggestions from here? Regards, Duane Johnson P.S. I'm CC'ing the Haskell Cafe so that our journey so far can be archived. On Apr 6, 2009, at 12:22 PM, Alberto Ruiz wrote: Hi Duane, I have seen your messages to Haskell Cafe but I am still thinking about the problem... :) Can you run simple matrix operations in ghci? $ ghci Prelude import Numeric.LinearAlgebra Prelude Numeric.LinearAlgebra let m = (22) [1..4 :: Double] (...Loading packages...) Prelude Numeric.LinearAlgebra m m (22) [ 7.0, 10.0 , 15.0, 22.0 ] If so, some version of blas/lapack can be found in your system, it is strange that ghc --make doesn't find them. Perhaps the problem is that dynamic libraries like liblapack.so are required instead of static ones like liblapack.a. (In ubuntu they are in the devel packages for blas/lapack.) I am not familiar with Mac OS, but if you can use the accelerate framework in your system you may try the -faccelerate configuration option for hmatrix: cabal install hmatrix -faccelerate See also the following page (steps 3-8). It explains how to install hmatrix on Mac OS (required for other project). http://mit.edu/harold/Public/easyVisionNotes.html Please let me know if any of these methods works for you. Thanks for your message, Alberto Duane Johnson wrote: Hi Alberto
[Haskell-cafe] Linking hmatrix without LAPACK
I'm curious if there is a quick fix to this. I installed GLS and hmatrix, and it runs wonderfully together in ghci. When I run ghc -- make, however, I run into the following link dependency: Linking SilkwormGame ... Undefined symbols: _dgemm_, referenced from: _multiplyR in libHShmatrix-0.5.0.1.a(lapack-aux.o) _dgesv_, referenced from: _linearSolveR_l in libHShmatrix-0.5.0.1.a(lapack-aux.o) ... etc Is there a way to tell ghc to not link these? Or am I making a poor assumption that if my code runs in ghci, it does not need LAPACK? Thanks, Duane Johnson ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Linking hmatrix without LAPACK
On a related note, I've installed Atlas, and I get the following error when linking: Linking SilkwormGame ... ld: in /opt/local/lib/liblapack.a(), not a valid archive member collect2: ld returned 1 exit status How would I go about diagnosing this? I've never seen an ld error like that. Thanks again! Duane Johnson On Apr 5, 2009, at 11:02 PM, Duane Johnson wrote: I'm curious if there is a quick fix to this. I installed GLS and hmatrix, and it runs wonderfully together in ghci. When I run ghc -- make, however, I run into the following link dependency: Linking SilkwormGame ... Undefined symbols: _dgemm_, referenced from: _multiplyR in libHShmatrix-0.5.0.1.a(lapack-aux.o) _dgesv_, referenced from: _linearSolveR_l in libHShmatrix-0.5.0.1.a(lapack-aux.o) ... etc Is there a way to tell ghc to not link these? Or am I making a poor assumption that if my code runs in ghci, it does not need LAPACK? Thanks, Duane Johnson ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Wishful thinking: a text editor that expands function applications into function definitions
So I was thinking about a killer feature for a text editor. Wouldn't it be neat if you could expand function calls into their definitions, in-place? For example, suppose we have minus defined like so, somewhere in another file: minus (a, b, c) (x, y, z) = (a - x, b - y, c - z) Later, we make use of the function in our current context: let p1 = (1, 2, 3) p2 = (4, 5, 6) in p1 `minus` p2 By telling the editor to expand the minus, we get a temporary replacing of the above with: (1 - 4, 2 - 5, 3 - 6) Another example: parse s = map readLine ls And supposing that readLine is defined somewhere else, moving the cursor to readLine in the line above and expanding becomes: parse s = map (\line - words $ dropWhile (== ' ') line) This is all pretty standard for the kinds of things we do in Haskell to work it out by hand, but is there any reason the parser couldn't do this? I think it would be even harder to do automatically in any other language. Maybe it's already been attempted or done? Curious, Duane Johnson ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Wishful thinking: a text editor that expands function applications into function definitions
Perhaps it wouldn't be as all-wonderful as I think, but as a new Haskell user, I am constantly switching back and forth between various definitions of things trying to compare documentation and files... The purpose of expansion as I was explaining it is not to *permanently replace* what is in the text, but rather to *temporarily replace* it. I imagine it kind of like a zoom in for code. You could zoom in on one function, and seeing a new function that you don't recognize, zoom in again, and so on. Once done, you would hit ESC to make it all return as it was. BTW, I do like your suggestion of tooltip types. That would be very handy! Duane Johnson On Apr 2, 2009, at 6:24 PM, Zachary Turner wrote: It seems like a neat feature, and it could just be my inexperience with Haskell but it doesn't seem killer. For example, why would you want to expand readLine like that if you already have it defined? It seems to defeat much of the benefit of functional languages in the first place, which is that it's so easy to reuse code by composing functions into new functions. I can see the case where you're passing all constants to a function, because then supposedly inlining it might be more efficient, but I would think the compiler would optimize most of the cases for you anyway. One feature that I -do- think would be killer though, is the ability for the editor to do a mouse-over tooltip of a) function definitions, and b) arbitrary expressions. So like in your example above, hovering the mouse over `minus` in the expression p1 `minus` p2 would pop up a two line tooltip that looked like this minus :: (Num a, Num b, Num c) = (a,b,c) - (a,b,c) - (a,b,c) minus :: first - second - (a,b,c) Something along those lines. It's nice to be able to see names of function arguments without having to navigate away from the line you're editing. This isn't the killer yet though since it's actually pretty standard for most sufficiently advanced programming language IDEs. The killer is that the mouse-over event would also look one line above the function definition for a comment. It would then scan backward until it finds no more comments. It would then display that text above the function definition. It's great having a type signature, but comments would just be icing on the cake. For arbitrary expressions, suppose you had the following function: replaceItem :: [a] - (a - Bool) - a - [a] let replaceItem xs pred = (: filter (not.pred) xs) You then highlight the text filter (not.pred) and hover over the highlighted text. The mouse then pops up a tooltip that says [a] - [a]. That would be killer IMO On Thu, Apr 2, 2009 at 7:01 PM, Duane Johnson duane.john...@gmail.com wrote: So I was thinking about a killer feature for a text editor. Wouldn't it be neat if you could expand function calls into their definitions, in-place? For example, suppose we have minus defined like so, somewhere in another file: minus (a, b, c) (x, y, z) = (a - x, b - y, c - z) Later, we make use of the function in our current context: let p1 = (1, 2, 3) p2 = (4, 5, 6) in p1 `minus` p2 By telling the editor to expand the minus, we get a temporary replacing of the above with: (1 - 4, 2 - 5, 3 - 6) Another example: parse s = map readLine ls And supposing that readLine is defined somewhere else, moving the cursor to readLine in the line above and expanding becomes: parse s = map (\line - words $ dropWhile (== ' ') line) This is all pretty standard for the kinds of things we do in Haskell to work it out by hand, but is there any reason the parser couldn't do this? I think it would be even harder to do automatically in any other language. Maybe it's already been attempted or done? Curious, Duane Johnson ___ 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
Re: [Haskell-cafe] Wishful thinking: a text editor that expands function applications into function definitions
I hadn't seen that feature in Excel before. When I press F9 it seems to evaluate the expression, which isn't quite what I had in mind (Mac OS). Is that the same as what you get? Duane On Apr 2, 2009, at 8:33 PM, Michael Snoyman wrote: 2009/4/3 Duane Johnson duane.john...@gmail.com Perhaps it wouldn't be as all-wonderful as I think, but as a new Haskell user, I am constantly switching back and forth between various definitions of things trying to compare documentation and files... The purpose of expansion as I was explaining it is not to *permanently replace* what is in the text, but rather to *temporarily replace* it. I imagine it kind of like a zoom in for code. You could zoom in on one function, and seeing a new function that you don't recognize, zoom in again, and so on. Once done, you would hit ESC to make it all return as it was. Sounds exactly like the F9 feature in Excel (that's where you got the idea, right?). I can personally attest that it can be an incredibly useful feature. Michael ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANNOUNCE: vacuum: extract graph representations of ghc heap values.
Hi Matt, That looks pretty neat. Can you explain a little more about what I'm seeing in these visualizations, and where this kind of visualization would be most useful? (Debugging, algorithm tuning, etc.)? Take care, Duane Johnson http://blog.inquirylabs.com/ On Mar 30, 2009, at 10:54 PM, Matt Morrow wrote: I am pleased to announce the release of vacuum, a Haskell library for extracting graph representations of values from the GHC heap, which may then be further processed and/or translated to Graphviz dot format to be visualized. The package website is at http://moonpatio.com/vacuum/, which contains a gallery section (which i intend to add to over time). The most recent version is 0.0.6, which is available on Hackage: http://hackage.haskell.org/cgi-bin/hackage-scripts/package/vacuum/. Feedback, comments, and/or gallery submissions will be gratefully received via this email address (contrary to the email address currently on the vacuum Hackage page (i fail at setting up email :)). Matt ___ 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
Re: [Haskell-cafe] ANNOUNCE: vacuum: extract graph representations of ghc heap values.
Ah, I hadn't read Don's thread before posting my previous comment. That cleared things up for me :) Thanks! Duane Johnson On Mar 30, 2009, at 10:54 PM, Matt Morrow wrote: I am pleased to announce the release of vacuum, a Haskell library for extracting graph representations of values from the GHC heap, which may then be further processed and/or translated to Graphviz dot format to be visualized. The package website is at http://moonpatio.com/vacuum/, which contains a gallery section (which i intend to add to over time). The most recent version is 0.0.6, which is available on Hackage: http://hackage.haskell.org/cgi-bin/hackage-scripts/package/vacuum/. Feedback, comments, and/or gallery submissions will be gratefully received via this email address (contrary to the email address currently on the vacuum Hackage page (i fail at setting up email :)). Matt ___ 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
Re: [Haskell-cafe] type Rational and the % operator
I believe it's import Data.Ratio I found it on hayoo... http://holumbus.fh-wedel.de/hayoo/hayoo.html?query=%25#0 :%25 -- Duane Johnson On Mar 28, 2009, at 7:39 PM, michael rice wrote: Hi, I've been away from Haskell Land for a while, but I think the function cf below, given a list of Ints should calculate a continuous fraction. I'm using Hugs 98 and get errors when loading and also when trying to use the % operator at the command prompt (see below). What must I do to get this to work? Michael === cf :: [Int] - Rational cf [] = 0 cf (x:[]) = 1 % x cf (x:xs) = x + (1 % cf xs) Hugs :load cf.hs ERROR cf.hs:2 - Undefined variable % Hugs Hugs 1 % 5 ERROR - Undefined variable % Hugs ___ 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
Re: [Haskell-cafe] Making videos of your project
Cool! Thanks, Don. I enjoyed the show :) Duane Johnson On Mar 24, 2009, at 2:20 AM, Don Stewart wrote: Hey guys, I've been making quick youtube videos of projects to convey what they do. Here, for example, using Tim Docker's Charts library in ghci: http://www.youtube.com/watch?v=2Lqzygxvus0 (Click on the HD button for higher res). Or one of Neil Brown's SG OpenGL graphics library, http://www.youtube.com/watch?v=tJ6AtfcorkY You can create your own really simply: 1. install 'recordmydesktop' I use: recordmydesktop --no-sound --v_bitrate 200 2. type 'recordmydesktop' 3. do something with haskell 4. hit control-C 5. upload out.ogv to youtube If you're a library author of one of the 2 or 3D packages, please consider video along with other why I want to use this material. -- Don ___ 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
Re: [Haskell-cafe] ghci + hopengl
Neat, thanks for that tip Peter. It looks like mkbundl does everything I do manually, and more. But just for the record, in case anyone (Scott?) wants to do it the hard way... :) 1. Download the macosx-app shell script from wxhaskell. Make it executable (i.e. chmod a+x macosx-app) 2. Run macosx-app [executable-filename], e.g. macosx-app Playground 3. Run open [generated app directory], e.g. open Playground.app I also blogged about it here. Duane Johnson http://blog.inquirylabs.com/ On Mar 24, 2009, at 4:48 PM, Peter Verswyvelen wrote: On Tue, Mar 24, 2009 at 11:35 PM, Scott A. Waterman tswater...@gmail.com wrote: Duane - yes, please. I've been wondering how to compile to a Mac .app structure. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/mkbndl Also, anyone have any hints about distributing Haskell apps for mac, when you know the target will certianly *not* have a GHC environment on it? GHC statically links everything, so you don't need the GHC environment to run the app. Thanks --ts On Mar 21, 2009, at 2:18 PM, Duane Johnson wrote: I've had issues with ghci and opengl... I usually have to compile my programs before they will run. I'm not sure why that's the case, but I too get strange window behavior (sometimes it freezes, other times it doesn't even show up). If you're on a Mac and would like help compiling to a .app folder, let me know and I can post how I did that. Regards, Duane Johnson http://blog.inquirylabs.com/ ___ 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
Re: [Haskell-cafe] Learning Haskell
I second that! Haskell is a very fun and engaging language (with its accompanying corpus of theorems, and its great community)... My timing is a little bit longer than Rick's... I've been eyeing Haskell for about 8 months, reading books, poking around etc. I've started to feel comfortable enough in the last month to begin a serious(ish) project. For my debut, I'm trying to build a game with HOpenGL. I wouldn't take my 8-month timeline as much of a benchmark, however, since I have not been very deeply involved in studying the language (I have no projects that require day-to-day coding in Haskell). Duane Johnson http://blog.inquirylabs.com/ On Mar 23, 2009, at 9:13 PM, Rick R wrote: I've been messing with Haskell since the Middle of January on evenings and weekends. Just now I'm getting to the point where I can construct nontrivial programs with little help from #haskell. It is by no means my most proficient language, I've been coding C++ and other languages for over 10 years. It is by far my favorite, however, and if I could do it full time I would. On Mon, Mar 23, 2009 at 11:08 PM, Tom.Amundsen tomamund...@gmail.com wrote: How long did it take you to become proficient in Haskell? By that, I mean - how long until you were just as comfortable with Haskell as you were with your strongest language at that time? -- View this message in context: http://www.nabble.com/Learning-Haskell-tp22673552p22673552.html Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- We can't solve problems by using the same kind of thinking we used when we created them. - A. Einstein ___ 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
Re: [Haskell-cafe] ghci + hopengl
I've had issues with ghci and opengl... I usually have to compile my programs before they will run. I'm not sure why that's the case, but I too get strange window behavior (sometimes it freezes, other times it doesn't even show up). If you're on a Mac and would like help compiling to a .app folder, let me know and I can post how I did that. Regards, Duane Johnson http://blog.inquirylabs.com/ On Mar 21, 2009, at 1:27 PM, Rafael Cunha de Almeida wrote: Hello, I'm writing a program for plotting vectorial functions and maybe something else in the future. My goal is to be able to have the following usage: Prelude :l Galo.hs Prelude Galo show3Dvec (\t - (t, t, 0)) [0.0,0.01 .. 1.0] * shows graph * Prelude Galo show3Dvec (\t - (t, t**2, 0)) [0.0,0.01 .. 1.0] * shows new graph * I already done something, the main module can be found here: http://github.com/aflag/galo/blob/0a54a53db0f66384cfc0775f12582931d0fb4205/Galo.hs The whole project is found here: http://github.com/aflag/galo/tree/master I think mainLoop is somehow responsible to exit the whole thing. I tried to even call that function through forkIO. But didn't work quite well: my terminal started behaving really weird after I closed the window. Could you explain me what is going on and what should I look into for understanding how to solve the issue? []'s Rafael ___ 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
Re: [Haskell-cafe] New Cabal FAQ
As a new Haskell user, I have to heartily agree about the sign-posts. Cabal is a superb, easy-to-use command-line tool for Haskell package management, but browsing various getting started with Haskell pages didn't lead me to clear instructions that cabal exists and that it is really important to install. In addition, may I suggest that the very first thing under Quick Links at http://haskell.org/cabal/ should be the following: Get Cabal Currently, the first link is How to install a Cabal package which was quite confusing for me as a new user, since I knew I wanted the cabal command on my system and that getting it is a prerequisite to installing cabal packages. Next, in a round-about manner, the link sends the user to http://haskell.org/haskellwiki/Cabal/How_to_install_a_Cabal_package which is fairly dense reading considering that the user is just trying to get cabal. At the bottom of the third paragraph of that page, it links to http://haskell.org/haskellwiki/Cabal-Install. The Cabal-Install page itself provides an introduction paragraph stating that there exists a caball-install package which sounds enticing--- but wait, is it a package? Doesn't that mean I need cabal to install cabal-install? What's going on here Strangely, the Usage section is listed before the Installation section which further confounded me until I read everything carefully. So in retrospect, I would have very much appreciated something like this (my blog entry to future Haskellers). Perhaps we could create the Get Cabal page and split it down the middle, one side for Windows and one side for Mac OS X / Linux / Unix. It should be very minimal and have all of the necessary steps first with commentary later in case things go wrong or the visitor decides to return for details. It also might be a good idea to use the cabal-specific pages on the wiki to redirect the user to the official cabal page where the official instructions reside since they show up in Google searches Duane Johnson http://blog.inquirylabs.com/ On Mar 21, 2009, at 3:44 PM, Duncan Coutts wrote: Hi all, I should have done this ages ago but there's now a Cabal FAQ on the Cabal website: http://haskell.org/cabal/FAQ.html It's not linked in yet, I'm looking for feedback and patches. The Cabal website is now maintained in darcs so it's easy to send in contributions: darcs get http://haskell.org/cabal/ For new pages like the FAQ I've been using markdown via pandoc. If appropriate we can migrate old pages to use that too. The main Cabal home page needs some love. We should have the cabal-install download directly on the front page. We should have quick intro tutorials for using the cabal command line program to install packages. There's lots of good material in the user guide but it is not well sign-posted. Duncan ___ 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
Re: [Haskell-cafe] Re: A guess on stack-overflows - thunksbuild-upand tail recursion
I just found out about GHood through this thread, and since it impressed me very much to see something so cool, I feel bad making this comment... but I am always disturbed by the flickering effect produced by java applets in my browser (FF 3.0) while scrolling. From an implementation standpoint this is obviously a nitpick, but from a designer standpoint it nearly single-handedly kills any prospect of my putting it up on a page. With that said, I think the canvas+js idea is a wonderful alternative to proprietary Flash. Regards, Duane Johnson On Mar 20, 2009, at 5:36 PM, Claus Reinke wrote: It would be great to have a video of this in action up on youtube. You can simply 'recordmydesktop' on linux (and likely elsewhere), then upload the result. I'm curious: how would a non-interactive animation running in Flash in a browser be better than an interactive animation running in Java in a browser?-) When I wrote GHood (many years ago), I explicitly looked into the applet option, in the hope that people would use it to document and discuss observation logs of their favourite Haskell strictness issues, with animations available on their web pages, right next to the discussions. That hasn't happened yet (the only users I was aware of were the DrHylo/Pointless Haskell project), but I just checked, the old .jar file, the source of which hasn't been perused for a long time, still worked in applet mode (in Opera, a browser I didn't know about in 2001, using a Java Runtime several versions removed from that time - try that in Haskell.. ;-), straight from that old project page (which also explains how to set such things up), so anyone could add animations of their favourite examples on their web-pages. But don't let that keep you or anyone else from addressing the youtube audience (one could add audio explanations, I guess). Claus PS. Perhaps these days, someone should rewrite the log viewer in Canvas+JavaScript as a more lightweight and modern platform. It also helps the general adoption cause, having Haskell more visible and accessible. claus.reinke: The problem occurs when the result value is needed and thus the thunks need to be reduced, starting with the outermost, which can't be reduced without reducing the next one etc and it's these reduction steps that are pushed on the stack until its size cause a stack-overflow. Yes, that's exactly right, and something that's not often pointed out. Btw, this is kind of relative strictness (when is one part of my program needed to answer demands on another part) is the kind of example for which old GHood can be helpful (once you get used to the display). If you have Java on your machines, try installing GHood [1] (on hackage thanks to Hugo Pacheco), then things like ghc -e ':m +Debug.Observe' -e 'printO $ observe foldr foldr (+) 0 [1..4] ' ghc -e ':m +Debug.Observe' -e printO $ observe \foldl'\ foldl' (+) 0 [1..4] ghc -e ':m +Debug.Observe' -e 'printO $ observe foldl foldl (+) 0 [1..4] ' This was also among the examples on the GHood home page [2], so you could try the applet version instead, and in section 4.2 of the paper [3] (as a well known strictness problem;-). Page and paper mention a few other similar examples and discuss some differences between static (which parts are needed at all) and dynamic strictness (which parts are needed when, relative to other demands). Claus [1] http://hackage.haskell.org/cgi-bin/hackage-scripts/package/GHood [2] http://www.cs.kent.ac.uk/~cr3/toolbox/haskell/GHood [3] http://www.cs.kent.ac.uk/~cr3/publications/GHood.html ___ 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 ___ 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
[Haskell-cafe] Why do functions not inherit class when renamed?
I'm not sure I understand what is going on here, but it seems to me that the following assignment of mult = (*) causes mult to lose out on some of the polymorphic behavior of (*). Is that right? If so, why? Prelude Data.Function Data.List Data.Char let sizeMult = (*) `on` length Prelude Data.Function Data.List Data.Char sizeMult Duane Johnson 35 Prelude Data.Function Data.List Data.Char let mult = (*) Prelude Data.Function Data.List Data.Char let sizeMult2 = mult `on` length interactive:1:26: Couldn't match expected type `Integer' against inferred type `Int' In the second argument of `on', namely `length' In the expression: mult `on` length In the definition of `sizeMult2': sizeMult2 = mult `on` length Prelude Data.Function Data.List Data.Char Thanks, Duane Johnson http://blog.inquirylabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Who generates Haskell code and uses type information at runtime? (fwd)
Out of curiosity, do you know if HaRe works for 6.10? The page only mentions GHC 6.6 and 6.8. Duane Johnson http://blog.inquirylabs.com/ On Mar 18, 2009, at 6:14 AM, Chris Brown wrote: I'm not sure if you got my previous message, as I was having some problems posting to the list... Putting in a nutshell, I generalize an extensional defined function definition into a recursive one. This is done in a number of steps by modifying expressions and exploiting type information of sub-expressions. For example: rev [] = [] rev [a] = [a] rev [a,b] = [b,a] rev [a,b,c] = [c,b,a] ~~ rev x = y ~~ rev [] = [] rev (x:xs) = (y:ys) ~~ rev [] = [] rev (x:xs) = (last (x:xs)) : (reverse (x:xs)) The initial set of rules is given by the user (in a file, via IO, ...). The problem later is to infer the type of an intermediate variable, e.g. 'y'. I'm still not entirely sure what you want to do here. But it sounds like HaRe could already do most of this for you via a sequence of folds, unfolds, introduce pattern matching and generative folding. HaRe already has built-in support for some symbolic evaluation, which is already used in the generative fold refactoring, and has type checking support too. http://www.cs.kent.ac.uk/projects/refactor-fp/hare.html If it doesn't do exactly what you want out of the tin, it does have a large API for designing transformations over Haskell code. http://www.cs.kent.ac.uk/projects/refactor-fp/hare/haddock/RefacUtils.html Chris. Thanks, Martin ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- Chris Brown Visualization Software Engineer, Peiriannydd Meddalwedd Delweddu. Cast Ltd., Technium CAST, Ffordd Penlan, Parc Menai, Bangor, Gwynedd UK. LL57 4HJ. Tel: +44 (0)1248 675038 Fax: +44 (0)1248 675012 Mobile: +44 (0)7917 763712 -- Centre for Advanced Software Technology Limited is a limited company registered in England and Wales. Registered Number: 04473521, Registered Office: Finance Office, Bangor University, College Road, Bangor, Gwynedd. LL57 2DG. ___ 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
Re: [Haskell-cafe] darcs fundraising drive - THANK-YOU!
I'm just getting to know this community, and I have to say, I am very impressed by this. Congrats to everyone for making the world a better place :) -- Duane Johnson On Mar 16, 2009, at 6:09 AM, Eric Kow wrote: Dear darcs users and Haskellers, I wanted to thank you all for your contributions to our first darcs fundraising drive. We've done it! We managed to raise $1000, over two weeks with contributions from 22 donors. This means that we will able to help our programmers travel to the darcs hacking sprint. This fundraising drive is over, but donations will still be gratefully accepted. In the long term, we hope to raise another $5000 to pay for a summer project ($4000) and also to pay for travel (another $1000) to the third hacking sprint this October or November. Again, thank-you! -- Eric Kow http://www.nltg.brighton.ac.uk/home/Eric.Kow PGP Key ID: 08AC04F9 ___ 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
[Haskell-cafe] Loading 3D points normals into OpenGL?
Hi, I am considering writing a VRML (.wrl) parser so that I can load points and normals for a game I'm making in Haskell. Is there something around that will already do the trick? Or perhaps another format is preferred and already supported? Thanks, Duane Johnson (canadaduane) http://blog.inquirylabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Loading 3D points normals into OpenGL?
The MTL portion of that library depends on an external DevIL library ... is there a way to specify just the Obj portion which has no such dependency? Thanks, Duane On Mar 11, 2009, at 5:28 PM, Luke Palmer wrote: You might be interested in the obj library: http://hackage.haskell.org/cgi-bin/hackage-scripts/package/obj Luke On Wed, Mar 11, 2009 at 5:23 PM, Duane Johnson duane.john...@gmail.com wrote: Hi, I am considering writing a VRML (.wrl) parser so that I can load points and normals for a game I'm making in Haskell. Is there something around that will already do the trick? Or perhaps another format is preferred and already supported? Thanks, Duane Johnson (canadaduane) http://blog.inquirylabs.com/ ___ 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
