[Haskell-cafe] Re: What do _you_ want to see in FGL?

2010-05-18 Thread Heinrich Apfelmus
Ivan Lazar Miljenovic wrote: > Heinrich Apfelmus writes: >> Ivan Lazar Miljenovic wrote: >>> >>> Well, we'll provide a Map-based one that lets you specify the vertex >>> type as a type parameter; this functionality (type parameter being ued >>> for the vertex type) won't be required since not all g

Re: [Haskell-cafe] Re: What do _you_ want to see in FGL?

2010-05-18 Thread Ivan Lazar Miljenovic
Heinrich Apfelmus writes: > Yes; what I mean is that you can retrofit a custom vertex type to any > graph implementation that uses a fixed vertex type. So, let's say that > >data Gr a b = .. -- graph with vertex type Vertex Gr = Int > > then > >type Gr' node a b = CustomVertex node Gr a b

Re: [Haskell-cafe] [reactive] A pong and integrate

2010-05-18 Thread Limestraël
> I heard complaints about this two-layered solution with > SignalMonad/SignalGen, so I'm glad you like it. :) Doesn't SignalGen replace SignalMonad in the experimental branch ? They aren't meant to be used together, are they? > By the way, I strongly recommend using the Experimental branch inste

Re: [Haskell-cafe] Wait forever in main thread

2010-05-18 Thread John Millikin
On Mon, May 17, 2010 at 19:41, David Leimbach wrote: > Is there not a way to multiplex the signal handlers into one thread, and > then dispatch new threads to do the work when events that require such > concurrency occur? > That would be the initial way I'd structure such a program. All signals,

Re: [Haskell-cafe] [reactive] A pong and integrate

2010-05-18 Thread Patai Gergely
> Doesn't SignalGen replace SignalMonad in the experimental branch ? They > aren't meant to be used together, are they? Absolutely, they are incompatible, and play the same role in the respective versions. > But there is no notion of time, here. So how do I make sure the network > is updated with

Re: [Haskell-cafe] Wait forever in main thread

2010-05-18 Thread David Leimbach
On Tue, May 18, 2010 at 7:08 AM, John Millikin wrote: > On Mon, May 17, 2010 at 19:41, David Leimbach wrote: > > Is there not a way to multiplex the signal handlers into one thread, and > > then dispatch new threads to do the work when events that require such > > concurrency occur? > > That wou

Re: [Haskell-cafe] Wait forever in main thread

2010-05-18 Thread David Leimbach
On Tue, May 18, 2010 at 8:06 AM, David Leimbach wrote: > > > On Tue, May 18, 2010 at 7:08 AM, John Millikin wrote: > >> On Mon, May 17, 2010 at 19:41, David Leimbach wrote: >> > Is there not a way to multiplex the signal handlers into one thread, and >> > then dispatch new threads to do the work

[Haskell-cafe] cabal-install

2010-05-18 Thread Serguey Zefirov
Why there is no switch to turn off any use of proxy in cabal-install? Or to supply username/password pair in command line. I have a strange situation: wget works like charm ignoring proxy (I downloaded Cabal and cabal-install to investigate the problem using wget), Firefox works like charm igoring

[Haskell-cafe] Performance Issue

2010-05-18 Thread Richard Warburton
A colleague of mine pointed out that ghc wasn't performing as he expected when optimising some code. I wonder if anyone could offer any insight as to why its not noting this common subexpression: main = print $ newton 4 24 newton a 0 = a newton a n = ((newton a (n-1))^2 + a)/(2*(newton a (n-1))

Re: [Haskell-cafe] Performance Issue

2010-05-18 Thread Bryan O'Sullivan
On Tue, May 18, 2010 at 9:30 AM, Richard Warburton < richard.warbur...@gmail.com> wrote: > A colleague of mine pointed out that ghc wasn't performing as he > expected when optimising some code. I wonder if anyone could offer > any insight as to why its not noting this common subexpression: GHC

Re: [Haskell-cafe] Performance Issue

2010-05-18 Thread Richard Warburton
>> A colleague of mine pointed out that ghc wasn't performing as he >> expected when optimising some code.  I wonder if anyone could offer >> any insight as to why its not noting this common subexpression: > > GHC performs almost no common subexpression elimination, the reasons being > that it can

Re: [Haskell-cafe] Performance Issue

2010-05-18 Thread Serguey Zefirov
2010/5/18 Richard Warburton : >> GHC performs almost no common subexpression elimination, the reasons being >> that it can introduce space leaks and undesired extra laziness. > Is there any way to encourage it to do so, for example compilation > flags?  Or is it generally best to hand apply these k

Re: [Haskell-cafe] Performance Issue

2010-05-18 Thread Bryan O'Sullivan
On Tue, May 18, 2010 at 9:43 AM, Richard Warburton < richard.warbur...@gmail.com> wrote: > Is there any way to encourage it to do so, for example compilation flags? No. It would be difficult for the compiler to see when CSE is or is not safe to apply, and so it doesn't have any code to perform f

Re: [Haskell-cafe] executeFile failing on macosx

2010-05-18 Thread Donn Cave
Quoth David Powell , > Indeed System.Process does work for me. I had avoided it because it is a > little more awkward to use it when you want the actual PIDs. I don't > understand why System.Process.runProcess works for me, but executeFile does > not. I did find this issue (for python) > http:/

Re: [Haskell-cafe] [reactive] A pong and integrate

2010-05-18 Thread Limestraël
Time has to be an external signal? I saw dow uses the Simple experimental branch, and I don't see how you synchronize elerea with GLFW (what is done by driveNetwork in the Chase and Breakout examples which use the main branch). 2010/5/18 Patai Gergely > > Doesn't SignalGen replace SignalMonad in

Re: [Haskell-cafe] GADTs and Scrap your Boilerplate

2010-05-18 Thread Oscar Finnsson
Hi, thanks for all the great feedback. > Your GADT encodes an existential datatype. The closest attempt to encode > existential types in (something like) SYB that I know of is in Section 5.3 of > Alexey's PhD thesis [1]. Having said that, he uses the spine view, which > makes the generic view

Re: [Haskell-cafe] Wait forever in main thread

2010-05-18 Thread John Millikin
On Tue, May 18, 2010 at 08:06, David Leimbach wrote: > I think you just said the same thing I just said.  So are we arguing?  I'm > kind of confused.  "If some computation needs to be performed, a thread is > spawned" is very similar to what I just said about multiplexing the signal > handling int

[Haskell-cafe] Help with Bird problem 1.4.1

2010-05-18 Thread R J
Newbie trying to get through Bird. Could someone provide a clean solution, with proof (so I can see how these proofs are laid out), to this: Given: f :: Integer -> Integerg :: Integer -> (Integer -> Integer) h :: ...h x y = f (g x y) Questions: a. Fill in the type assignment for "h". b. Which

Re: [Haskell-cafe] Help with Bird problem 1.4.1

2010-05-18 Thread Daniel Fischer
On Tuesday 18 May 2010 21:49:50, R J wrote: > Newbie trying to get through Bird. Could someone provide a clean > solution, with proof (so I can see how these proofs are laid out), to > this: Given: > f :: Integer -> Integer > g :: Integer -> (Integer -> Integer) > h :: ... > h x y = f (g x y) > Q

[Haskell-cafe] cabal: problem building ffi shared library and significance of __stginit

2010-05-18 Thread Anthony LODI
Hello, I'm trying to build some haskell code as a .so/.dll so that it can ultimately be used by msvc. I have it working when I compile by hand (listed below) but I can't get the exact same thing built/linked with cabal. On linux everything builds fine, but when I try to link the resulting .so fi

Re: [Haskell-cafe] [reactive] A pong and integrate

2010-05-18 Thread Patai Gergely
> Time has to be an external signal? With the Simple version, yes. With the Param (and Delayed) versions it's pretty much like the old one, where you have to pass something (delta time being one possibility) as an additional parameter, and all stateful and transfer nodes will see it. > I saw dow u

Re: [Haskell-cafe] cabal-install

2010-05-18 Thread Ivan Lazar Miljenovic
Serguey Zefirov writes: > Why there is no switch to turn off any use of proxy in cabal-install? > Or to supply username/password pair in command line. > > I have a strange situation: wget works like charm ignoring proxy (I > downloaded Cabal and cabal-install to investigate the problem using > wg

[Haskell-cafe] Re: GADTs and Scrap your Boilerplate

2010-05-18 Thread John Creighton
On May 18, 11:57 am, Oscar Finnsson wrote: > > forall d.   gunfold k z c = k (z (DataBox::d->DataBox d)) > > Didn't work either. :( I looked again at the paper (page 27): Haskell's Overlooked object system. http://homepages.cwi.nl/~ralf/OOHaskell/paper.pdf I think the forall is suppose to be i

Re: [Haskell-cafe] Re: GADTs and Scrap your Boilerplate

2010-05-18 Thread Alexander Solla
On May 18, 2010, at 3:27 PM, John Creighton wrote: I looked again at the paper (page 27): Haskell's Overlooked object system. http://homepages.cwi.nl/~ralf/OOHaskell/paper.pdf Is there any particular reason why you like that paper so much? Object orientation is nice, when you're dealing wi

[Haskell-cafe] Type families vs. functional dependencies -- how to express something

2010-05-18 Thread Tomáš Janoušek
Hello all, for the past few hours I've been struggling to express a certain idea using type families and I really can't get it to typecheck. It all works fine using functional dependencies, but it could be more readable with TFs. From those papers about TFs I got this feeling that they should be a

Re: [Haskell-cafe] Type families vs. functional dependencies -- how to express something

2010-05-18 Thread Dan Weston
> Unifying those two types by hand, I get: > > P (A t -> B a) > ~> P (B a) Maybe the problem is that type families (and associated types, their class cousins) are not injective: P x ~ P y does not imply that x ~ y. Maybe you need a data type (with appropriate wrapping and unwrapping) to e

Re: [Haskell-cafe] [reactive] A pong and integrate

2010-05-18 Thread Limestraël
> The game speed is determined by the amount of sleep > per frame. I that the saw sleep time at each loop is fixed (0.02). So game speed will depend on processor speed, since with a more powerful CPU frames will be computed quicklier? So we don't have (with the Simple branch) some way to say "I wa

[Haskell-cafe] Intuitive function given type signature

2010-05-18 Thread R J
What are some simple functions that would naturally have the following type signatures: f :: (Integer -> Integer) -> Integer g :: (Integer -> Integer) -> (Integer -> Integer) (Bird problem 1.4.5) __

Re: [Haskell-cafe] Intuitive function given type signature

2010-05-18 Thread Ivan Miljenovic
This looks suspiciously like homework... 2010/5/19 R J : > What are some simple functions that would naturally have the following type > signatures: > f :: (Integer -> Integer) -> Integer I can only think of one solution to this but it doesn't guarantee that it returns a value... > g :: (Integer

Re: [Haskell-cafe] Intuitive function given type signature

2010-05-18 Thread Miguel Mitrofanov
On 19 May 2010, at 08:35, Ivan Miljenovic wrote: This looks suspiciously like homework... 2010/5/19 R J : What are some simple functions that would naturally have the following type signatures: f :: (Integer -> Integer) -> Integer I can only think of one solution to this but it doesn't gu

Re: [Haskell-cafe] Intuitive function given type signature

2010-05-18 Thread Ivan Miljenovic
2010/5/19 Miguel Mitrofanov : > > On 19 May 2010, at 08:35, Ivan Miljenovic wrote: >> >> 2010/5/19 R J : >>> >>> What are some simple functions that would naturally have the following >>> type >>> signatures: >>> f :: (Integer -> Integer) -> Integer >> >> I can only think of one solution to this bu

Re: [Haskell-cafe] [reactive] A pong and integrate

2010-05-18 Thread Patai Gergely
> I that the saw sleep time at each loop is fixed (0.02). So game speed > will > depend on processor speed, since with a more powerful CPU frames will be > computed quicklier? Yes, that's how it works. > So we don't have (with the Simple branch) some way to say "I want my > sprite > to move 100 pi

Re: [Haskell-cafe] cabal-install

2010-05-18 Thread Serguey Zefirov
2010/5/19 Ivan Lazar Miljenovic : > Serguey Zefirov writes: >> Why there is no switch to turn off any use of proxy in cabal-install? >> Or to supply username/password pair in command line. >> I have a strange situation: wget works like charm ignoring proxy (I >> downloaded Cabal and cabal-install