date:20121129

Re: [Haskell-cafe] How can I avoid buffered reads?

2012-11-29 Thread Leon Smith

Well,  I took Bardur's suggestion and avoided all the complexities of GHC's
IO stack and simply used System.Posix.IO and Foreign.This appears to
work,  but for better or worse,   it is using blocking calls to the read
system call and is not integrated with GHC's IO manager.   This shouldn't
be an issue for my purposes,  but I suppose it's worth pointing out.

{-# LANGUAGE BangPatterns, ViewPatterns #-}

import   Control.Applicative
import   Data.Bits
import   Data.Word(Word64)
import qualified Data.ByteString as S
import qualified Data.ByteString.Lazy as L
import   Data.ByteString.Internal (c2w)
import   Control.Exception
import   System.Posix.IO
import   Foreign
import qualified System.IO  as IO
import qualified Data.Binary.Getas Get

showHex :: Word64 - S.ByteString
showHex n = s
  where
(!s,_) = S.unfoldrN 16 f n

f n = Just (char (n `shiftR` 60), n `shiftL` 4)

char (fromIntegral - i)
  | i  10= (c2w '0' -  0) + i
  | otherwise = (c2w 'a' - 10) + i

twoRandomWord64s :: IO (Word64,Word64)
twoRandomWord64s = bracket openRd closeRd readRd
  where
openRd = openFd /dev/urandom ReadOnly Nothing defaultFileFlags {
noctty = True }
readRd = \fd - allocaBytes 16 $ \ptr - do
fdReadAll fd ptr 16
x - peek (castPtr ptr)
y - peek (castPtr ptr `plusPtr` 8)
return (x,y)
closeRd = closeFd
fdReadAll fd ptr n = do
  n' - fdReadBuf fd ptr n
  if n /= n'
  then fdReadAll fd (ptr `plusPtr` n') (n - n')
  else return ()

main = do
   (x,y) - twoRandomWord64s
   S.hPutStrLn IO.stdout (S.append (showHex x) (showHex y))


On Wed, Nov 28, 2012 at 6:05 PM, Leon Smith leon.p.sm...@gmail.com wrote:

 If you have rdrand,  there is no need to build your own PRNG on top of
 rdrand.   RdRand already incorporates one so that it can produce random
 numbers as fast as they can be requested,  and this number is continuously
 re-seeded with the on-chip entropy source.

 It would be nice to have a little more information about /dev/urandom and
 how it varies by OS and hardware,   but on Linux and FreeBSD at least it's
 supposed to be a cryptographically secure RNG that incorporates a PRNG to
 produce numbers in case you exhaust the entropy pool.

 On Wed, Nov 28, 2012 at 5:00 PM, Vincent Hanquez t...@snarc.org wrote:

 On 11/28/2012 09:31 PM, Leon Smith wrote:

 Quite possibly,  entropy does seem to be a pretty lightweight
 dependency...

 Though doesn't recent kernels use rdrand to seed /dev/urandom if it's
 available?   So /dev/urandom is the most portable source of random numbers
 on unix systems,  though rdrand does have the advantage of avoiding system
 calls,  so it certainly would be preferable, especially if you need large
 numbers of random numbers.

 There's no much information on this i think, but if you need large number
 of random numbers you should build a PRNG yourself on top of the best
 random seed you can get, and make sure you reseed your prng casually with
 more entropy bytes. Also if
 you don't have enough initial entropy, you should block.

 /dev/urandom is not the same thing on every unix system. leading to
 various assumptions broken when varying the unixes. It also varies with the
 hardware context: for example on an embedded or some virtualized platform,
 giving you really terrible entropy.

 --
 Vincent



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Re: [Haskell-cafe] Can not use ST monad with polymorphic function

2012-11-29 Thread Dmitry Kulagin

Thank you, MigMit!

If I replace your type FoldSTVoid with:
data FoldMVoid = FoldMVoid {runFold :: Monad m = (Int - m ()) - m ()}

then everything works magically with any monad!
That is exactly what I wanted, though I still do not quite understand why
wrapping the type solves the problem

Dmitry


On Thu, Nov 29, 2012 at 12:01 AM, MigMit miguelim...@yandex.ru wrote:

 Yes, monomorphism. do binding requires your fold'' to be of some
 monomorphic type, but runST requires some polymorphism.

 If you want, you can use special type like that:

 data FoldSTVoid = FoldSTVoid {runFold :: forall a. (Int - ST a ()) - ST
 a ()}

 fold :: Monad m = (Int - m ()) - m ()
 fold f = mapM_ f [0..20]

 selectFold :: String - IO FoldSTVoid -- ((Int - m ()) - m ())
 selectFold method = do
 -- in real program I'd like to choose between
 -- different fold methods, based on some IO context
 return $ FoldSTVoid fold

 useFold :: FoldSTVoid - ST a ()
 useFold fold' = runFold fold' f
 where f _ = return () -- some trivial iterator

 main = do
 fold'' - selectFold some-method-id
 print $ runST $ useFold fold''

 On Nov 28, 2012, at 9:52 PM, Dmitry Kulagin dmitry.kula...@gmail.com
 wrote:

  Hi Cafe,
 
  I try to implement some sort of monadic fold, where traversing is
 polymorphic over monad type.
  The problem is that the code below does not compile. It works with any
 monad except for ST.
  I suspect that monomorphism is at work here, but it is unclear for me
 how to change the code to make it work with ST.
 
  fold :: Monad m = (Int - m ()) - m ()
  fold f = mapM_ f [0..20]
 
  selectFold :: Monad m = String - IO ((Int - m ()) - m ())
  selectFold method = do
  -- in real program I'd like to choose between
  -- different fold methods, based on some IO context
  return fold
 
  useFold :: Monad m = ((Int - m ()) - m ()) - m ()
  useFold fold' = fold' f
  where f _ = return () -- some trivial iterator
 
  main = do
  fold'' - selectFold some-method-id
  print $ runST $ useFold fold''
 
 
  Thank you!
  Dmitry
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Re: [Haskell-cafe] SOX - play simple

2012-11-29 Thread Antoine Latter

The example is assuming you have an import statement like this:

import qualified Sound.Sox.Option.Format as Option

On Wed, Nov 28, 2012 at 8:48 AM, Gary Klindt gary.kli...@googlemail.com wrote:
 Dear Cafe,

 after installing the Sox library
 (cabal install sox)
 I wanted to let run a minimal example from
 http://hackage.haskell.org/packages/archive/sox/0.2.2.2/doc/html/Sound-Sox-Play.html


 module Main where

 import Sound.Sox.Play
 import Sound.Sox.Signal.List
 --import Sound.Sox.Option.Format

 import Data.Int

 main = do
 simple Sound.Sox.Signal.List.put
Option.none
11025
(iterate (1000+) (0::Data.Int.Int16))

 in this version, I get the error:
  Not in scope: `Option.none'

 So, I imported Sound.Sox.Option.Format, because there is a none with the
 right type. I also changed Option.none to none.

 Then the program compiles and I get the runtime error:
 fd:4: hClose: resource vanished (Broken pipe)


 What is wrong here?

 I appreciate your help!

 Best regards, Gary

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[Haskell-cafe] Simple GUI Form

2012-11-29 Thread Rune Harder Bak

Hi

I have some input parameters
data Input = ...
that I need the user to enter in a gui pop-up. (windows people...)
The rest of the app is not gui (or perhaps progress could be displayed
in a log-window)

What is the easiest way to make such a GUI form?

It need to compile for both Linux and Windows, so I though WxWidgets was ideal,
and I got wx[1]  0.90 to install (using wxWidgets2.8) on both windows
and linux.

Now I just need to create the form, but how do you do that?
Any clues or links to examples? I have never used wxwidgets on any
platform or done any other form of GUI before for that matters.
(apart from some Visual Basic ten years ago, and html).

I tried looking at wx examples, but I couldn't find this simple use
case explained anywhere.

I installed wx in the first place because WxGeneric[2] seemed exactly
what I needed,
but I can't get it to compile using ghc7.4.2 from haskell-platform.
Anybody got that working or have some other simple method?

Help much appreciated!

-Rune

[1] http://hackage.haskell.org/package/wx-0.13.2.3
[2] http://hackage.haskell.org/package/WxGeneric

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Re: [Haskell-cafe] Simple GUI Form

2012-11-29 Thread Ertugrul Söylemez

Hi there Rune,

if you want to get started with declarative GUI programming in Haskell,
I really recommend taking the FRP route.  Check out the
reactive-banana-wx [1] library instead of using wxHaskell directly.  If
you manage to get wxHaskell working on Windows, then reactive-banana
will work as well.

[1]: http://www.haskell.org/haskellwiki/Reactive-banana


Greets,
Ertugrul


Rune Harder Bak r...@bak.dk wrote:

 I have some input parameters
 data Input = ...
 that I need the user to enter in a gui pop-up. (windows people...)
 The rest of the app is not gui (or perhaps progress could be displayed
 in a log-window)
 
 What is the easiest way to make such a GUI form?
 
 It need to compile for both Linux and Windows, so I though WxWidgets
 was ideal, and I got wx[1]  0.90 to install (using wxWidgets2.8) on
 both windows and linux.
 
 Now I just need to create the form, but how do you do that?
 Any clues or links to examples? I have never used wxwidgets on any
 platform or done any other form of GUI before for that matters.
 (apart from some Visual Basic ten years ago, and html).
 
 I tried looking at wx examples, but I couldn't find this simple use
 case explained anywhere.
 
 I installed wx in the first place because WxGeneric[2] seemed exactly
 what I needed,
 but I can't get it to compile using ghc7.4.2 from haskell-platform.
 Anybody got that working or have some other simple method?
 
 Help much appreciated!
 
 -Rune
 
 [1] http://hackage.haskell.org/package/wx-0.13.2.3
 [2] http://hackage.haskell.org/package/WxGeneric

-- 
Not to be or to be and (not to be or to be and (not to be or to be and
(not to be or to be and ... that is the list monad.


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Re: [Haskell-cafe] delete http://www.haskell.org/haskellwiki/Haskell_IDE

2012-11-29 Thread Roman Beslik


Good point. Done.

On 29.11.12 06:16, Conrad Parker wrote:

#REDIRECT [[IDEs]]


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Re: [Haskell-cafe] Simple GUI Form

2012-11-29 Thread Rune Harder Bak

I'm very interested in FRP,  but all the examples I could see was
forms with live feedback
gui like a real-time calculator.
This is a one-time form where the user fills everything in, clicks on a button,
where after the computations might take a long time, perhaps display
some console-info.
But maybe this is a good use-case for reactive-banana as well?
Do you have any good examples in this regard?

On Thu, Nov 29, 2012 at 2:37 PM, Ertugrul Söylemez e...@ertes.de wrote:
 Hi there Rune,

 if you want to get started with declarative GUI programming in Haskell,
 I really recommend taking the FRP route.  Check out the
 reactive-banana-wx [1] library instead of using wxHaskell directly.  If
 you manage to get wxHaskell working on Windows, then reactive-banana
 will work as well.

 [1]: http://www.haskell.org/haskellwiki/Reactive-banana


 Greets,
 Ertugrul


 Rune Harder Bak r...@bak.dk wrote:

 I have some input parameters
 data Input = ...
 that I need the user to enter in a gui pop-up. (windows people...)
 The rest of the app is not gui (or perhaps progress could be displayed
 in a log-window)

 What is the easiest way to make such a GUI form?

 It need to compile for both Linux and Windows, so I though WxWidgets
 was ideal, and I got wx[1]  0.90 to install (using wxWidgets2.8) on
 both windows and linux.

 Now I just need to create the form, but how do you do that?
 Any clues or links to examples? I have never used wxwidgets on any
 platform or done any other form of GUI before for that matters.
 (apart from some Visual Basic ten years ago, and html).

 I tried looking at wx examples, but I couldn't find this simple use
 case explained anywhere.

 I installed wx in the first place because WxGeneric[2] seemed exactly
 what I needed,
 but I can't get it to compile using ghc7.4.2 from haskell-platform.
 Anybody got that working or have some other simple method?

 Help much appreciated!

 -Rune

 [1] http://hackage.haskell.org/package/wx-0.13.2.3
 [2] http://hackage.haskell.org/package/WxGeneric

 --
 Not to be or to be and (not to be or to be and (not to be or to be and
 (not to be or to be and ... that is the list monad.

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Re: [Haskell-cafe] Simple GUI Form

2012-11-29 Thread Ertugrul Söylemez

Rune Harder Bak r...@bak.dk wrote:

 I'm very interested in FRP, but all the examples I could see was forms
 with live feedback gui like a real-time calculator.
 This is a one-time form where the user fills everything in, clicks on
 a button, where after the computations might take a long time, perhaps
 display some console-info.
 But maybe this is a good use-case for reactive-banana as well?

Of course.  There is no reason to think that FRP is limited to real-time
applications with complicated interactions.


 Do you have any good examples in this regard?

Not myself, but there is a somewhat comprehensive tutorial [1] as well
as lots of examples [2] linked from the wiki.

I just want to stress the importance of the last tutorial section:  FRP
is not a concrete design pattern, but rather a family of them.  The
tutorial explains FRP as understood and implemented specifically by
reactive-banana.  There are a number of other practical libraries that
use different notions, in particular of events.

[1]: http://www.haskell.org/haskellwiki/
  FRP_explanation_using_reactive-banana
[2]: http://www.haskell.org/haskellwiki/Reactive-banana/Examples


Greets,
Ertugrul

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Re: [Haskell-cafe] Observer pattern in haskell FRP

2012-11-29 Thread Heinrich Apfelmus


Nathan Hüsken wrote:

Heinrich Apfelmus wrote:


Personally, I would recommend is a complete change in perspective.

The main idea of FRP is that it is a method to describe the evolution of
values in time. What is a game? It's just a picture that evolves in
time. The user can exert influence on the evolution by clicking certain
buttons on a mechanical device, but in the end, all he sees is a picture
that moves. [..]


That perspective certainly make sense. But couldn't one also describe a
game as a set of entities (spaceships) that react to the clicking of
buttons?


Of course, generally speaking, you can describe it any way you like, FRP 
is just a perspective, not a dictatorial doctrine.


But you probably mean that you want to describe spaceships within the 
FRP perspective, though independent of how they are displayed. That's a 
good point, which I missed. (The guideline of working backwards from the 
very final result has served me very well when developing in FRP style, 
though, hence my insistence on it.)


In the FRP perspective, I would use a slightly different language, 
though. Namely, I would not say that spaceships are entities that react 
to button clicks, but rather that they are represented by time-varying 
positions that depend on past button clicks. The change is subtle but 
important: you invert the direction of control. Instead of having a 
button click do something to the spaceship (push), you have a 
spaceship whose present position depends on past button clicks (pull).


The FRP perspective is also more holistic: you can think of a 
spaceship and other time-varying values as if you knew their values for 
all points in time, as if you were given graphical plots. (I have drawn 
a few pretty pictures in the slides linked to here 
http://apfelmus.nfshost.com/blog/2012/07/15-frp-tutorial-slides.html)



If I take for example the breakout game from here [1]. It outputs an
object scene of type Picture. But this picture is calculated from the
objects ballPos and paddlePos. So first a game state (ballPos,
paddlePos) is created and than transformed to something renderable.

I believe all examples I have seen for games with FRP follow this
pattern, and I would I want to do is seperate the steps of calculating
the game state and calculating the renderable from it.


In that light, the separation seems straightforward to me. Given the 
time-varying values that represent game objects,


   bSpaceShipPosition :: Behavior Position
   bAsteroidPositions :: Behavior [Position]
   bTime  :: Behavior Time

you can transform and combine them into a graphic, for instance like this

   bSpaceShipPicture :: Behavior Graphic
   bSpaceShipPicture =
   blinkenLights $ bTime * bSpaceShipPosition

   bAsteroidPictures = map drawAsteroid $ bAsteroidPositions

   bPicture = overlay $
   ((:) $ bSpaceShipPicture * bAsteroidPictures)

In other words, you just combine old time-varying values into new ones, 
much like you would combine combine graphical plots. Also note that you 
can add animation a posteriori; it doesn't have to be part of the values 
representing a space ship.



Of course, one important question is whether to represent asteroid 
positions as a time-varying collection  Behavior [Position]  or as a 
collection of time-varying values  [Behavior Position] . The latter form 
tends to require dynamic event switching, while the former form tends 
towards a monolithic  GameState  value, which would forgo many of the 
advantages of FRP.


I don't have enough practical experience to give a useful recommendation 
here, but at the moment, I tend towards breaking it up as much as 
possible, but trying to avoid dynamic event switching. My rule of thumb 
is to model similar objects (asteroids) as a time-varying collection, 
while modeling distinct objects (player space ship) as individual behaviors.



Best regards,
Heinrich Apfelmus

--
http://apfelmus.nfshost.com


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[Haskell-cafe] lambda case (was Re: A big hurray for lambda-case (and all the other good stuff))

2012-11-29 Thread Jon Fairbairn

Ben Franksen ben.frank...@online.de writes:

 just wanted to drop by to say how much I like the new lambda case extension. 
 I use it all the time and I just *love* how it relieves me from conjuring up 
 dummy variables, which makes teh code not only esier to write but also to 
 read.

 […] should *definitely* go into Haskell'13.

As I was opposed to the suggestion for lambda case I didn’t
really follow the discussion of the syntax, but I’m puzzled by
the choice. To me it seems obvious that if we are going to do
this (as opposed to something more decomposable like
lambda-match), we should do it simply by making the “case exp”
part of a case expression optional. So the syntax for lambda-
case would be

   of {alts…}

and we would then describe

   case e of {…}

as syntactic sugar for

   (of {…}) (e)

Doing it this way doesn’t introduce any new syntactic elements
and has fewer tokens at the point of use.

I don’t see any need for a \ in the syntax: this is a functional
language we are talking about after all. Once we know that “of”
introduces a function, that should be enough.

-- 
Jón Fairbairn jon.fairba...@cl.cam.ac.uk


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[Haskell-cafe] To my boss: The code is cool, but it is about 100 times slower than the old one...

2012-11-29 Thread Fixie Fixie

Hi all haskellers

I every now and then get the feeling that doing my job code in Haskell would be
a good idea.

I have tried a couple of times, but each time I seem to run into performance
problems - I do lots of heavy computing.

The problem seems to be connected to lazy loading, which makes my programs so
slow that I really can not show them to anyone. I have tried all tricks in the
books, like !, seq, non-lazy datatypes...

I was poking around to see if this had changed, then I ran into this forum
post: http://stackoverflow.com/questions/9409634/is-indexing-of-data-vector-unboxed-mutable-mvector-really-this-slow

The last solution was a haskell program which was in the 3x range to C, which I
think is ok. This was in the days of ghc 7.0

I then tried compile the programs myself (ghc 7.4.1), but found that now the C
program now was more that 100x faster. The ghc code was compiled with both O2
and O3, giving only small differences on my 64-bit Linux box.

So it seems something has changed - and even small examples are still not safe
when it comes to the lazy-monster. It reminds me of some code I read a couple
of years ago where one of the Simons actually fired off a new thread, to make
sure a variable was realized.

A sad thing, since I am More that willing to go for Haskell if proves to be
usable. If anyone can see what is wrong with the code (there are two haskell
versions on the page, I have tried the last and fastest one) it would also be
interesting.

What is your experience, dear haskellers? To me it seems this beautiful
language is useless without a better lazy/eager-analyzer.

Cheers,

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Re: [Haskell-cafe] To my boss: The code is cool, but it is about 100 times slower than the old one...

2012-11-29 Thread Alfredo Di Napoli

Hi there,
I'm only an amateur so just my 2 cent: Haskell can be really fast, but
reaching that speed can be all but trivial: you need to use different data
types (e.g. ByteString vs. the normal String type) relies on
unconventional IO (e.g. Conduit, Iterateee) and still be ready to go out
of the base, using packages and functions wich are not in base/haskell
platform (e.g. mwc-random).

My 2 cents :)
A.

On 29 November 2012 18:09, Fixie Fixie fixie.fi...@rocketmail.com wrote:

Hi all haskellers

I every now and then get the feeling that doing my job code in Haskell
would be a good idea.

I have tried a couple of times, but each time I seem to run into
performance problems - I do lots of heavy computing.

The problem seems to be connected to lazy loading, which makes my programs
so slow that I really can not show them to anyone. I have tried all tricks
in the books, like !, seq, non-lazy datatypes...

I was poking around to see if this had changed, then I ran into this forum
post:
http://stackoverflow.com/questions/9409634/is-indexing-of-data-vector-unboxed-mutable-mvector-really-this-slow

The last solution was a haskell program which was in the 3x range to C,
which I think is ok. This was in the days of ghc 7.0

I then tried compile the programs myself (ghc 7.4.1), but found that now
the C program now was more that 100x faster. The ghc code was compiled with
both O2 and O3, giving only small differences on my 64-bit Linux box.

So it seems something has changed - and even small examples are still not
safe when it comes to the lazy-monster. It reminds me of some code I read a
couple of years ago where one of the Simons actually fired off a new
thread, to make sure a variable was realized.

A sad thing, since I am More that willing to go for Haskell if proves to
be usable. If anyone can see what is wrong with the code (there are two
haskell versions on the page, I have tried the last and fastest one) it
would also be interesting.

What is your experience, dear haskellers? To me it seems this beautiful
language is useless without a better lazy/eager-analyzer.

Cheers,

Felix

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Re: [Haskell-cafe] Simple GUI Form

2012-11-29 Thread timothyhobbs

I know it's not wx, but if you were willing to use GTK, you could simply 
install:

http://hackage.haskell.org/package/gtk-jsinput

and generate the form automatically as described in:

https://github.com/timthelion/gtk-jsinput/blob/master/Graphics/UI/Gtk/
Custom/JSInput.hs



Timothy




-- Původní zpráva --
Od: Rune Harder Bak r...@bak.dk
Datum: 29. 11. 2012
Předmět: [Haskell-cafe] Simple GUI Form

Hi

I have some input parameters
data Input = ...
that I need the user to enter in a gui pop-up. (windows people...)
The rest of the app is not gui (or perhaps progress could be displayed
in a log-window)

What is the easiest way to make such a GUI form?

It need to compile for both Linux and Windows, so I though WxWidgets was 
ideal,
and I got wx[1]  0.90 to install (using wxWidgets2.8) on both windows
and linux.

Now I just need to create the form, but how do you do that?
Any clues or links to examples? I have never used wxwidgets on any
platform or done any other form of GUI before for that matters.
(apart from some Visual Basic ten years ago, and html).

I tried looking at wx examples, but I couldn't find this simple use
case explained anywhere.

I installed wx in the first place because WxGeneric[2] seemed exactly
what I needed,
but I can't get it to compile using ghc7.4.2 from haskell-platform.
Anybody got that working or have some other simple method?

Help much appreciated!

-Rune

[1] http://hackage.haskell.org/package/wx-0.13.2.3
(http://hackage.haskell.org/package/wx-0.13.2.3)
[2] http://hackage.haskell.org/package/WxGeneric
(http://hackage.haskell.org/package/WxGeneric)

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Re: [Haskell-cafe] To my boss: The code is cool, but it is about 100 times slower than the old one...

2012-11-29 Thread Johan Tibell

Hi Felix,

On Thu, Nov 29, 2012 at 10:09 AM, Fixie Fixie
fixie.fi...@rocketmail.com wrote:
The problem seems to be connected to lazy loading, which makes my programs
so slow that I really can not show them to anyone. I have tried all tricks
in the books, like !, seq, non-lazy datatypes...

My advice usually goes like this:

1. Use standard, high-performance libraries (I've made a list of high
quality libraries at
https://github.com/tibbe/haskell-docs/blob/master/libraries-directory.md).
2. Make your data type fields strict.
3. Unpack primitive types (e.g. Int, Word, Float, Double).
4. Reduce allocation in tight loops (e.g. avoid creating lots of
intermediate lists).

I always do 1-3, but only do 4 when it's really necessary (e.g. in the
inner loop of some machine learning algorithm).

Rarely is performance issues due to lacking bang patterns on functions
(although there are cases, e.g. when writing recursive functions with
accumulators, where you need one).

I was poking around to see if this had changed, then I ran into this forum
post:
http://stackoverflow.com/questions/9409634/is-indexing-of-data-vector-unboxed-mutable-mvector-really-this-slow

The last solution was a haskell program which was in the 3x range to C,
which I think is ok. This was in the days of ghc 7.0

I then tried compile the programs myself (ghc 7.4.1), but found that now the
C program now was more that 100x faster. The ghc code was compiled with both
O2 and O3, giving only small differences on my 64-bit Linux box.

So it seems something has changed - and even small examples are still not
safe when it comes to the lazy-monster. It reminds me of some code I read a
couple of years ago where one of the Simons actually fired off a new thread,
to make sure a variable was realized.

Note that the issues in the blog post are not due to laziness (i.e.
there are no space leaks), but due to the code being more polymorphic
than the C code, causing extra allocation and indirection.

What is your experience, dear haskellers? To me it seems this beautiful
language is useless without a better lazy/eager-analyzer.

It's definitely possible to write fast Haskell code (as some Haskell
programmers manage to do so consistently), but I appreciate that it's
harder than it should be. In my opinion the major thing missing is a
good text on how to write fast Haskell code and some tweaks to the
compiler (e.g. unbox strict primitive fields like Int by default).

Hope this helps.

Cheers,
Johan

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Re: [Haskell-cafe] To my boss: The code is cool, but it is about 100 times slower than the old one...

2012-11-29 Thread Ivan Salazar

I hear you, my friend.

What I love of Haskell is that a lot of algorithms are very clean to
express and understand compared to, say, Lisp or C. Compared to Lisp,
function manipulation is also very clean (even compared to Racket). A great
plus is also type inference.

The bad side is that direct translation of algorithms are almost always
very slow and the work needed to make them perform is very mind bending. I
sometimes feel as if I am doing the work of a compiler/optimizer and wonder
if a computer program can do this translations.

In the correct hands (the Simons, Don Stewart, etc) I am sure Haskell is a
killer, but in hands of lowly, imperative mortals it is a time bomb. A good
example of this is narrated in Clarke's
Superiorityhttp://www.mayofamily.com/RLM/txt_Clarke_Superiority.html
.

I am a total Haskell newbie, so please ignore me if my opinion sounds
stupid, but I think I read once that Peyton-Jones said that the Haskell of
the future will be strict.

Thanks!

2012/11/29 Fixie Fixie fixie.fi...@rocketmail.com