May 2016 - Beginners - Haskell.org

Apology
by Peter McIlroy 05 May '16

05 May '16

Apologies for the two bad messages. I won't attempt responding by phone to this list anymore.

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Sieve of Aritosthenes
by Peter McIlroy 05 May '16

05 May '16

Apologies for the empty post. You might turn your attention to the following web page, which approaches the problem using recursive co-routines. Amidst a discussion of UNIX pipes, both in history and as a primitive co-routine implementation, there is a two-line Haskell program. http://www.cs.dartmouth.edu/~doug/sieve/ -----Original Message----- From: "beginners-request(a)haskell.org" <beginners-request(a)haskell.org> Sent: ‎5/‎5/‎2016 11:10 AM To: "beginners(a)haskell.org" <beginners(a)haskell.org> Subject: Beginners Digest, Vol 95, Issue 8 Send Beginners mailing list submissions to beginners(a)haskell.org To subscribe or unsubscribe via the World Wide Web, visit http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners or, via email, send a message with subject or body 'help' to beginners-request(a)haskell.org You can reach the person managing the list at beginners-owner(a)haskell.org When replying, please edit your Subject line so it is more specific than "Re: Contents of Beginners digest..." Today's Topics: 1. Re: Timed Profiling (Vale Cofer-Shabica) 2. Re: Infinite recursion in list comprehension (Silent Leaf) 3. Re: Infinite recursion in list comprehension (Silent Leaf) ---------------------------------------------------------------------- Message: 1 Date: Thu, 5 May 2016 10:38:50 -0400 From: Vale Cofer-Shabica <vale.cofershabica(a)gmail.com> To: The Haskell-Beginners Mailing List - Discussion of primarily beginner-level topics related to Haskell <beginners(a)haskell.org> Subject: Re: [Haskell-beginners] Timed Profiling Message-ID: <CAAzfV4Rse76Yw8Vq_Mqny_cFRw_9_FFcXBAAm4W+54zXWTuveQ(a)mail.gmail.com> Content-Type: text/plain; charset="utf-8" timeout(1) allows you to specify the signal(7) sent with the --signal option. It may be worth experimenting with different values. One of them might terminate the program while allowing it to clean up and generate profiling information. I don't know enough about the haskell runtime to know. -vale -- vale cofer-shabica 401.267.8253 On Wed, May 4, 2016 at 7:06 PM, Tim Perry <tim.v2.0(a)gmail.com> wrote: > I believe that timeout sends a kill signal to the process in question. I > imagine that the process is killed before the profiling information is > written and so you get an empty file. When you close the program with > alt-F4, the program gets a chance to shut down cleanly and writes on the > profiling information (.prof) > > > On Wed, May 4, 2016 at 9:11 AM, Ben Rogalski <bwrogalski(a)gmail.com> wrote: > >> I would like to generate a time and allocation profiling report after >> running my program for exactly 60 seconds (on Ubuntu Linux). >> >> I compiled with the following flags: >> >> -rtsopts -auto-all -caf-all -fforce-recomp >> >> I then ran the program: >> >> The program stops after 60 seconds, but the .prof file is empty. >> >> When I run the program without using timeout, and close it manually (Alt >> F4, it is a graphical program), the .prof file contains the information I >> would expect. >> >> _______________________________________________ >> Beginners mailing list >> Beginners(a)haskell.org >> http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners >> >> > > _______________________________________________ > Beginners mailing list > Beginners(a)haskell.org > http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners > >

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Re: [Haskell-beginners] Beginners Digest, Vol 95, Issue 8
by Peter McIlroy 05 May '16

05 May '16

-----Original Message----- From: "beginners-request(a)haskell.org" <beginners-request(a)haskell.org> Sent: ‎5/‎5/‎2016 11:10 AM To: "beginners(a)haskell.org" <beginners(a)haskell.org> Subject: Beginners Digest, Vol 95, Issue 8 Send Beginners mailing list submissions to beginners(a)haskell.org To subscribe or unsubscribe via the World Wide Web, visit http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners or, via email, send a message with subject or body 'help' to beginners-request(a)haskell.org You can reach the person managing the list at beginners-owner(a)haskell.org When replying, please edit your Subject line so it is more specific than "Re: Contents of Beginners digest..." Today's Topics: 1. Re: Timed Profiling (Vale Cofer-Shabica) 2. Re: Infinite recursion in list comprehension (Silent Leaf) 3. Re: Infinite recursion in list comprehension (Silent Leaf) ---------------------------------------------------------------------- Message: 1 Date: Thu, 5 May 2016 10:38:50 -0400 From: Vale Cofer-Shabica <vale.cofershabica(a)gmail.com> To: The Haskell-Beginners Mailing List - Discussion of primarily beginner-level topics related to Haskell <beginners(a)haskell.org> Subject: Re: [Haskell-beginners] Timed Profiling Message-ID: <CAAzfV4Rse76Yw8Vq_Mqny_cFRw_9_FFcXBAAm4W+54zXWTuveQ(a)mail.gmail.com> Content-Type: text/plain; charset="utf-8" timeout(1) allows you to specify the signal(7) sent with the --signal option. It may be worth experimenting with different values. One of them might terminate the program while allowing it to clean up and generate profiling information. I don't know enough about the haskell runtime to know. -vale -- vale cofer-shabica 401.267.8253 On Wed, May 4, 2016 at 7:06 PM, Tim Perry <tim.v2.0(a)gmail.com> wrote: > I believe that timeout sends a kill signal to the process in question. I > imagine that the process is killed before the profiling information is > written and so you get an empty file. When you close the program with > alt-F4, the program gets a chance to shut down cleanly and writes on the > profiling information (.prof) > > > On Wed, May 4, 2016 at 9:11 AM, Ben Rogalski <bwrogalski(a)gmail.com> wrote: > >> I would like to generate a time and allocation profiling report after >> running my program for exactly 60 seconds (on Ubuntu Linux). >> >> I compiled with the following flags: >> >> -rtsopts -auto-all -caf-all -fforce-recomp >> >> I then ran the program: >> >> The program stops after 60 seconds, but the .prof file is empty. >> >> When I run the program without using timeout, and close it manually (Alt >> F4, it is a graphical program), the .prof file contains the information I >> would expect. >> >> _______________________________________________ >> Beginners mailing list >> Beginners(a)haskell.org >> http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners >> >> > > _______________________________________________ > Beginners mailing list > Beginners(a)haskell.org > http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners > >

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Timed Profiling
by Ben Rogalski 05 May '16

05 May '16

I would like to generate a time and allocation profiling report after running my program for exactly 60 seconds (on Ubuntu Linux). I compiled with the following flags: -rtsopts -auto-all -caf-all -fforce-recomp I then ran the program: The program stops after 60 seconds, but the .prof file is empty. When I run the program without using timeout, and close it manually (Alt F4, it is a graphical program), the .prof file contains the information I would expect.

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Re: [Haskell-beginners] Double vs. Num
by Ben Rogalski 05 May '16

05 May '16

Tim and Christopher, here is my code. There is a lot of it, but I've tried to cut out the irrelevent parts. If I change the type of Transform3D.append from append :: (Floating a) => Transformer a -> Transform a -> Transformer a to append :: Transformer Double -> Transform Double -> Transformer Double The framerate goes from ~1400 fps to ~2200 fps. module Render where ... renderTree :: GLInfo -> Tree (Attribute Double) -> IO () renderTree (GLInfo names attribs uniforms) t = fst $ cFold2 f (return (),identity) t where f acc Hidden = Skip acc f (a,tr) (Transformation t) = Continue (a, append tr t) f (a,tr) (Clip b) = let (x1:.y1:._, x2:.y2:._) = extremes $ applyAABB tr b a' = do glUniform2f (uniforms M.! "maskMin") (realToFrac x1) (realToFrac y1) glUniform2f (uniforms M.! "maskMax") (realToFrac x2) (realToFrac y2) in Continue (a >> a', tr) f (a,tr) (Texture _ (x1:.y1:.x2:.y2:._)) = let a' = do glUniform1i (uniforms M.! "texSampler") 0 glUniform4f (uniforms M.! "uvCoords") (realToFrac x1) (realToFrac y1) (realToFrac x2) (realToFrac y2) glUniformMatrix4fv' (uniforms M.! "mvp") 1 (fromBool False) (map realToFrac $ transformerToList tr) glDrawElements gl_TRIANGLES (fromIntegral $ attribs M.! "iboLenSquare") gl_UNSIGNED_INT nullPtr in Continue (a >> a', tr) f acc _ = Continue acc ... module Transform3D where ... data Transform a = RotationZ a | Scale (Vec3 a) | Translation (Vec3 a) deriving (Eq, Read, Show) newtype Transformer a = Transformer (Vec4 (Vec4 a)) append :: (Floating a) => Transformer a -> Transform a -> Transformer a append (Transformer m) t = Transformer $ m #*# toMatrix t identity :: (Num a) => Transformer a identity = Transformer identityMatrix toMatrix :: (Floating a) => Transform a -> Vec4 (Vec4 a) toMatrix (RotationZ z) = rotationZMatrix z toMatrix (Scale (x:.y:.z:._)) = scaleMatrix x y z toMatrix (Translation (x:.y:.z:._)) = translationMatrix x y z identityMatrix :: (Num a) => Vec4 (Vec4 a) identityMatrix = (1:.0:.0:.0:.Nil):. (0:.1:.0:.0:.Nil):. (0:.0:.1:.0:.Nil):. (0:.0:.0:.1:.Nil):.Nil rotationZMatrix :: (Floating a) => a -> Vec4 (Vec4 a) rotationZMatrix a = let c = cos a s = sin a in (c:.(-s):.0:.0:.Nil):. (s:.c:.0:.0:.Nil):. (0:.0:.1:.0:.Nil):. (0:.0:.0:.1:.Nil):.Nil scaleMatrix :: (Num a) => a -> a -> a -> Vec4 (Vec4 a) scaleMatrix x y z = (x:.0:.0:.0:.Nil):. (0:.y:.0:.0:.Nil):. (0:.0:.z:.0:.Nil):. (0:.0:.0:.1:.Nil):.Nil translationMatrix :: (Num a) => a -> a -> a -> Vec4 (Vec4 a) translationMatrix x y z = (1:.0:.0:.x:.Nil):. (0:.1:.0:.y:.Nil):. (0:.0:.1:.z:.Nil):. (0:.0:.0:.1:.Nil):.Nil ... module Vector where ... infixr 5 :. --data Cons u t = (:.) t (u t) deriving (Eq, Read, Show) data Cons u t = (:.) ! t ! (u t) deriving (Eq, Read, Show) data Nil t = Nil deriving (Eq, Read, Show) ... (|*#) :: (Num t, Vector w, Vector u) => w t -> w (u t) -> u t (|*#) v m = (transpose m) #*| v (#*#) :: (Num t, Vector u, Vector v, Vector w) => u (v t) -> v (w t) -> u (w t) (#*#) x y = transpose $ fmap (x #*|) (transpose y) dot :: (Num t, Vector v) => v t -> v t -> t dot xs ys = sum ((*) <$> xs <*> ys) ...

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Double vs. Num
by Ben Rogalski 04 May '16

04 May '16

I have found that using the type Double in a type signature causes my program to run much faster than if I use a type variable with a Num constraint. Is this common, and if so, why is explicitly using Double faster?

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CAF taking all the memory
by Mahdi 03 May '16

03 May '16

Hello there, I’m pretty new to Haskell and I’m trying to write a Neural Network in Haskell for educational purposes. So, I have my neural network working, it can learn XOR in 500 iterations, but the thing is, if I increase the iterations to something like 5 milion times, the process just drains my RAM until either it’s killed or the OS drowns. Here is the code: [0] I searched online and tried to get information on why this is happening, I profiled the memory usage and found that the memory is taken by CAF, searching online, it seems like an optimization done by compiler to reduce runtime computations. Here is the profile: [1] I searched online on how to prevent this from happening, couldn’t find anything helpful. I found this [2] and tried the workaround, but it didn’t work. Is there any way to solve this problem? Because when I’m moving to more complex problems, I have to train with much more iterations, and it just doesn’t work. [0] https://github.com/mdibaiee/biscuit/blob/master/src/examples/xor.hs [1] https://gist.github.com/mdibaiee/95878469a80f1c448b8cf0762178720e [2] http://stackoverflow.com/questions/6090932/how-to-make-a-caf-not-a-caf-in-h… Thank you, – Mahdi

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ByteString unfold that can fail
by John Ky 03 May '16

03 May '16

Hello, Does anyone know of anything like Data.ByteString.unfoldr, except that it can fail with a return value? Cheers, -John

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audio generation
by Dennis Raddle 02 May '16

02 May '16

I'm writing a program that will use functions to generate audio. The Haskell code will write the audio samples to disk---no need for real time playback. I see some useful libraries for writing audio files. My question concerns efficiency when generating several million to 20 million samples (or even many times more than that if I use high-resolution sampling rates). They can be generated one at a time in sequence, so there's no need to occupy a lot of memory or postpone thunk evaluation. I'm going to need efficient disk writing. Note that I may need some pseudorandom numbers in my calculations, so I might want to calculate samples by state monadic computations to carry the generator state. What is my general strategy going to be for memory and time efficiency? I am pretty confused by Haskell "strictness" and normal head form and all that, which often doesn't seem to be very strict. Or bang patterns, etc. Is it going to be simple to understand what I need? Dennis

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Trying to prove Applicative is superclass of Functor, etc
by Silent Leaf 01 May '16

01 May '16

Hi, well aware it's trivial so I'll be terse: do we have?: > fmap = <*> . pure So we could write for example > liftA2 f fa fb = f <$> fa <*> fb this way?: > liftA2 f fa fb = pure f <*> fa <*> fb <*> Incidentally, do we have?: > liftA == liftM == fmap Thanks!

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