Re: [Haskell-cafe] Execution call graph pruning
Thanks Ivan. Regards, Kashyap On Wed, Jun 9, 2010 at 4:40 AM, Ivan Lazar Miljenovic ivan.miljeno...@gmail.com wrote: C K Kashyap ckkash...@gmail.com writes: Hi, I have a call grah which contains information of the edges in the following format caller callee count (time spent by the caller) === foo bar 10100 xxx yyy 2010 zzz yyy 1010 (I used pintool pintool.org to generate this call graph) Now, the problem is that the graph is huge and it take a long to render using 'dot' or use any visualizing tool. Even if they render, it's too cluttered to be useful. I wanted to prune the graph in such a way that I'd have only the edges corresponding to the top 10% of the time consumers. What would be a good way to do such a thing? Has anyone written some utility that I could use? Well, graphviz [1] lets you parse Dot code, so you could then do a filter on it (I'm currently working on ways of letting you interact with the Dot code better). [1]: http://hackage.haskell.org/package/graphviz Also, to let you skip a step prof2dot [2] will create the Dot code for you. [2]: http://hackage.haskell.org/package/prof2dot -- Ivan Lazar Miljenovic ivan.miljeno...@gmail.com IvanMiljenovic.wordpress.com -- Regards, Kashyap ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] A Finally Tagless Pi Calculus
Hello,
I studied (a bit) Pi-calculus and other mobile agents calculus during
my PhD, and I have always been fascinated by the beauty of this idea.
Your implementation is strikingly simple and beautiful.
I have a question though: Why is the fixpoint type
newtype Nu f = Nu { nu :: f (Nu f) }
needed? And BTW, why generally use fixpoint on types? I read some
papers using/presenting such constructions (most notable a paper by
R.Lammel, I think, on expression trees transformation) but never quite
get it.
Thanks
Arnaud
On Wed, Jun 9, 2010 at 6:20 PM, Edward Kmett ekm...@gmail.com wrote:
Keegan McAllister gave a very nice talk at Boston Haskell last night about
First Class Concurrency. His slides are available online at
http://t0rch.org/
His final few slides covered the Pi calculus:
http://en.wikipedia.org/wiki/Pi_calculus
I took a few minutes over lunch to dash out a finally tagless version of the
pi calculus interpreter presented by Keegan, since the topic of how much
nicer it would look in HOAS came up during the meeting.
For more information on finally tagless encodings, see:
http://www.cs.rutgers.edu/~ccshan/tagless/jfp.pdf
Of course, Keegan went farther and defined an encoding of the lambda
calculus into the pi calculus, but I leave that as an exercise for the
reader. ;)
-Edward Kmett
{-# LANGUAGE Rank2Types, TypeFamilies, FlexibleInstances #-}
module Pi where
import Control.Applicative
import Control.Concurrent
A finally tagless encoding of the Pi calculus. Symantics is a portmanteau of
Syntax and Semantics.
class Symantics p where
type Name p :: *
new :: (Name p - p) - p
out :: Name p - Name p - p - p
(|||) :: p - p - p
inn :: Name p - (Name p - p) - p
rep :: p - p
nil :: p
embed :: IO () - p
Type level fixed points
newtype Nu f = Nu { nu :: f (Nu f) }
fork :: IO () - IO ()
fork a = forkIO a return ()
forever :: IO a - IO a
forever p = p forever p
Executable semantics
instance Symantics (IO ()) where
type Name (IO ()) = Nu Chan
new f = Nu $ newChan = f
a ||| b = forkIO a fork b
inn (Nu x) f = readChan x = fork . f
out (Nu x) y b = writeChan x y b
rep = forever
nil = return ()
embed = id
A closed pi calculus term
newtype Pi = Pi { runPi :: forall a. Symantics a = a }
run :: Pi - IO ()
run (Pi a) = a
example = Pi (new $ \z - (new $ \x - out x z nil
||| (inn x $ \y - out y x $ inn x $ \
y - nil))
||| inn z (\v - out v v nil))
A pretty printer for the pi calculus
newtype Pretty = Pretty { runPretty :: [String] - Int - ShowS }
instance Symantics Pretty where
type Name Pretty = String
new f = Pretty $ \(v:vs) n -
showParen (n 10) $
showString nu . showString v . showString . .
runPretty (f v) vs 10
out x y b = Pretty $ \vs n -
showParen (n 10) $
showString x . showChar '' . showString y . showString .
.
runPretty b vs 10
inn x f = Pretty $ \(v:vs) n -
showParen (n 10) $
showString x . showChar '(' . showString v . showString ).
.
runPretty (f v) vs 10
p ||| q = Pretty $ \vs n -
showParen (n 4) $
runPretty p vs 5 .
showString | .
runPretty q vs 4
rep p = Pretty $ \vs n -
showParen (n 10) $
showString ! .
runPretty p vs 10
nil = Pretty $ \_ _ - showChar '0'
embed io = Pretty $ \_ _ - showString {IO}
instance Show Pi where
showsPrec n (Pi p) = runPretty p vars n
where
vars = fmap return vs ++
[i : show j | j - [1..], i - vs] where
vs = ['a'..'z']
Pi example
nu a. (nu b. (ba. 0 | b(c). cb. b(d). 0) | a(b). bb. 0)
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Re: [Haskell-cafe] Problems with threading?
Yeah, Control.Parallel would be nice to have. Heck, ideally I could get the whole Haskell Platform, which would be a reasonable comparison to the huge Java and C++ libraries accessible to those languages. Out of curiosity, though, Haskell's thread-ring implementation just *tumbled * down the rankings http://shootout.alioth.debian.org/u64q/program.php?test=threadringlang=ghcid=3. Previously, it'd been doing most of its work on a single core, now it's spread out. Any ideas for fixin' it? (I'm going to to try using forkOnIO.) Louis Wasserman wasserman.lo...@gmail.com http://profiles.google.com/wasserman.louis On Wed, Jun 9, 2010 at 6:18 PM, Don Stewart d...@galois.com wrote: igouy2: Now how do we get those regex-dna and binary-trees programs to compile? http://shootout.alioth.debian.org/u32/measurements.php?lang=ghc binary-trees: Could not find module `Control.Parallel.Strategies': -- cabal install parallel regex-dna: cannot satisfy -package regex-posix -- cabal install regex-posix Both are in Debian. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Removing alternate items from a list
From: Markus L?ll markus.l...@gmail.com So out of curiosity i took the definitions given in this thread, and tried to run timing-tests. Here's what I ran: ghc -prof -auto-all -o Test Test.h Test +RTS -p and then looked in the Test.prof file. I think this is a poor approach for timing tests, for two reasons: 1) -O or -O2. Reporting performance results from non-optimized builds is often highly misleading. 2) -auto-all inhibits performance of code, sometimes significantly. You'd be better off using a non-profiling build and criterion. Plus criterion does the statistics for you and warns about possibly invalid samples. John ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Contacting Planet Haskell
Jason Dagit wrote: I recently tried to send an email to the planet Haskell admins. The webpage says to use pla...@community.haskell.org. The mail was undelivered after several days and the daemon gave up trying to deliver it. Which daemon gave up, ours or yours? My sending did overlap with the haskell.org downtown but I don't think that should have been a problem because: 1) It looks like it retried after haskell.org was back up Irrelevent, because 2) I'm pretty sure community is a different host than haskell.org Right. 3) Shouldn't a backup mx handle this? Hard to say, I can't tell from your sketchy description what exactly went wrong. Please send more details to supp...@community.haskell.org to open a ticket. Anyway, that address is just an alias that forwards mail to the two real email addresses of the admins. I'll send you those off-list. Regards, Yitz ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] A Finally Tagless Pi Calculus
On Thu, Jun 10, 2010 at 3:52 AM, Arnaud Bailly arnaud.oq...@gmail.comwrote:
Hello,
I studied (a bit) Pi-calculus and other mobile agents calculus during
my PhD, and I have always been fascinated by the beauty of this idea.
Your implementation is strikingly simple and beautiful.
I have a question though: Why is the fixpoint type
newtype Nu f = Nu { nu :: f (Nu f) }
needed? And BTW, why generally use fixpoint on types? I read some
papers using/presenting such constructions (most notable a paper by
R.Lammel, I think, on expression trees transformation) but never quite
get it.
You need the Nu type because you need channels that can only send channels
of channels of channels of channels of ...
You could equivalently use the formulation
newtype NuChan = NuChan (Chan NuChan)
but then I couldn't recycle the wrapper for other types if I wanted.
Without it the code below it would be untype because of the occurs check.
If you look in category-extras under Control.Morphism.* you'll find a lot of
other uses of the types Mu/Nu though there the type is called FixF.
-Edward Kmett
On Wed, Jun 9, 2010 at 6:20 PM, Edward Kmett ekm...@gmail.com wrote:
Keegan McAllister gave a very nice talk at Boston Haskell last night
about
First Class Concurrency. His slides are available online at
http://t0rch.org/
His final few slides covered the Pi calculus:
http://en.wikipedia.org/wiki/Pi_calculus
I took a few minutes over lunch to dash out a finally tagless version of
the
pi calculus interpreter presented by Keegan, since the topic of how much
nicer it would look in HOAS came up during the meeting.
For more information on finally tagless encodings, see:
http://www.cs.rutgers.edu/~ccshan/tagless/jfp.pdf
Of course, Keegan went farther and defined an encoding of the lambda
calculus into the pi calculus, but I leave that as an exercise for the
reader. ;)
-Edward Kmett
{-# LANGUAGE Rank2Types, TypeFamilies, FlexibleInstances #-}
module Pi where
import Control.Applicative
import Control.Concurrent
A finally tagless encoding of the Pi calculus. Symantics is a portmanteau
of
Syntax and Semantics.
class Symantics p where
type Name p :: *
new :: (Name p - p) - p
out :: Name p - Name p - p - p
(|||) :: p - p - p
inn :: Name p - (Name p - p) - p
rep :: p - p
nil :: p
embed :: IO () - p
Type level fixed points
newtype Nu f = Nu { nu :: f (Nu f) }
fork :: IO () - IO ()
fork a = forkIO a return ()
forever :: IO a - IO a
forever p = p forever p
Executable semantics
instance Symantics (IO ()) where
type Name (IO ()) = Nu Chan
new f = Nu $ newChan = f
a ||| b = forkIO a fork b
inn (Nu x) f = readChan x = fork . f
out (Nu x) y b = writeChan x y b
rep = forever
nil = return ()
embed = id
A closed pi calculus term
newtype Pi = Pi { runPi :: forall a. Symantics a = a }
run :: Pi - IO ()
run (Pi a) = a
example = Pi (new $ \z - (new $ \x - out x z nil
||| (inn x $ \y - out y x $ inn x $
\
y - nil))
||| inn z (\v - out v v nil))
A pretty printer for the pi calculus
newtype Pretty = Pretty { runPretty :: [String] - Int - ShowS }
instance Symantics Pretty where
type Name Pretty = String
new f = Pretty $ \(v:vs) n -
showParen (n 10) $
showString nu . showString v . showString . .
runPretty (f v) vs 10
out x y b = Pretty $ \vs n -
showParen (n 10) $
showString x . showChar '' . showString y . showString .
.
runPretty b vs 10
inn x f = Pretty $ \(v:vs) n -
showParen (n 10) $
showString x . showChar '(' . showString v . showString ).
.
runPretty (f v) vs 10
p ||| q = Pretty $ \vs n -
showParen (n 4) $
runPretty p vs 5 .
showString | .
runPretty q vs 4
rep p = Pretty $ \vs n -
showParen (n 10) $
showString ! .
runPretty p vs 10
nil = Pretty $ \_ _ - showChar '0'
embed io = Pretty $ \_ _ - showString {IO}
instance Show Pi where
showsPrec n (Pi p) = runPretty p vars n
where
vars = fmap return vs ++
[i : show j | j - [1..], i - vs] where
vs = ['a'..'z']
Pi example
nu a. (nu b. (ba. 0 | b(c). cb. b(d). 0) | a(b). bb. 0)
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[Haskell-cafe] Using the ContT monads for early exits of IO ?
Hi everyone, I'm about to write a rather lengthy piece of IO code. Depending on the results of some of the IO actions I'd like the computation to stop right there and then. Now I know in general how to write this but I'm wondering if this is one of those occasions where I should make use of the Cont monad to make an early exit. Günther ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Removing alternate items from a list
Or, when lists had a decent eliminator defined in the Prelude (just like maybe for Maybe and either for Either): list :: b - (a - [a] - b) - [a] - b list d _ [] = d list _ f (x:xs) = f x xs fromList = list [] we could write the alternate function like this: alt :: [a] - [a] alt = list [] $ \a - (a:) . list [] (const alt) -- Sebastiaan On Jun 6, 2010, at 4:46 PM, R J wrote: What's the cleanest definition for a function f :: [a] - [a] that takes a list and returns the same list, with alternate items removed? e.g., f [0, 1, 2, 3, 4, 5] = [1,3,5]? The New Busy is not the old busy. Search, chat and e-mail from your inbox. Get started.___ 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] Removing alternate items from a list
Yep, the test is done by a rookie. If I get more time, I'll try to look into testing a little more, and redo the timing (if anyone doesn't do it firs) -- using optimizations, more runs per function and the criterion package. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Problems with threading?
--- On Thu, 6/10/10, Louis Wasserman wasserman.lo...@gmail.com wrote: Date: Thursday, June 10, 2010, 1:32 AM Yeah, Control.Parallel would be nice to have. Heck, ideally I could get the whole Haskell Platform, which would be a reasonable comparison to the huge Java and C++ libraries accessible to those languages. Out of curiosity, though, Haskell's thread-ring implementation just tumbled down the rankings http://shootout.alioth.debian.org /u64q/program.php?test=threadringlang=ghcid=3. Previously, it'd been doing most of its work on a single core, now it's spread out. Any ideas for fixin' it? (I'm going to to try using forkOnIO.) There are 4 sets of rankings so - http://shootout.alioth.debian.org/u64/program.php?test=threadringlang=ghcid=3 I have been wondering what approach is recommended when one part of a program would be a lot faster with -threaded but other parts of the program would be a lot faster without -threaded. I can see that the C++ and Fortran and ... programmers would just wrap part of their program source code with a pragma. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Using the ContT monads for early exits of IO ?
Yeah I don't see why not. The ContT monad should work great. Also, depending on what you're doing, the ErrorT monad might do what you want as well. - Job 2010/6/10 Günther Schmidt gue.schm...@web.de Hi everyone, I'm about to write a rather lengthy piece of IO code. Depending on the results of some of the IO actions I'd like the computation to stop right there and then. Now I know in general how to write this but I'm wondering if this is one of those occasions where I should make use of the Cont monad to make an early exit. 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] Using the ContT monads for early exits of IO ?
I have a general question about this kind of approach. Tutorials on continuations in Haskell always come with a warning about not using it unless you have to because it makes code unreadable and unmaintainable. Is this true in your opinion? -deech On 6/10/10, Job Vranish job.vran...@gmail.com wrote: Yeah I don't see why not. The ContT monad should work great. Also, depending on what you're doing, the ErrorT monad might do what you want as well. - Job 2010/6/10 Günther Schmidt gue.schm...@web.de Hi everyone, I'm about to write a rather lengthy piece of IO code. Depending on the results of some of the IO actions I'd like the computation to stop right there and then. Now I know in general how to write this but I'm wondering if this is one of those occasions where I should make use of the Cont monad to make an early exit. 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] Using the ContT monads for early exits of IO ?
Günther, This is definitely one way to do it. If you want to be able to quit the IO action in the middle of a lengthy computation, that is one way that I, personally, find very straightfoward. You can find an example of this in my Advgame package on Hackage, which uses this method to quit running the main action (although I could have used a conditional to determine whether to continue running the main loop, but continuations are more fun :P). Small example: foo = (`runContT` id) $ do dummy - callCC $ \exit - forever $ do line - liftIO getLine if line == quit then exit $ return () else ... -- do whatever else here... Cheers, - Tim 2010/6/10 Günther Schmidt gue.schm...@web.de Hi everyone, I'm about to write a rather lengthy piece of IO code. Depending on the results of some of the IO actions I'd like the computation to stop right there and then. Now I know in general how to write this but I'm wondering if this is one of those occasions where I should make use of the Cont monad to make an early exit. 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] Contacting Planet Haskell
On Thu, Jun 10, 2010 at 3:59 AM, Yitzchak Gale g...@sefer.org wrote: Jason Dagit wrote: I recently tried to send an email to the planet Haskell admins. The webpage says to use pla...@community.haskell.org. The mail was undelivered after several days and the daemon gave up trying to deliver it. Which daemon gave up, ours or yours? My sending did overlap with the haskell.org downtown but I don't think that should have been a problem because: 1) It looks like it retried after haskell.org was back up Irrelevent, because 2) I'm pretty sure community is a different host than haskell.org Right. 3) Shouldn't a backup mx handle this? Hard to say, I can't tell from your sketchy description what exactly went wrong. Please send more details to supp...@community.haskell.org to open a ticket. Anyway, that address is just an alias that forwards mail to the two real email addresses of the admins. I'll send you those off-list. Thanks. I emailed one of the admins directly and the problem seems to be resolved. Jason ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] How to Show an Operation?
On Thursday, 10. June 2010 00:08:34 Luke Palmer wrote: Or just: apply = val_of So, to summarize: if you have something that isn't a function and you want to use it like a function, convert it to a function (using another function :-P). That's all. No syntax magic, just say what you're doing. Thanks Luke The reason I was asking is the following: suppose I have some code which uses some functions, and what it primarily does with those functions is CALL them in different orders. Now at a later point in time I decide I need to give names to those functions because at the end I need to print information about the functions which together solved a certain problem. Think of my problem as In which order do I have to call f,g,h such that (f.g.h) 42 = 42?. I don't want to change all places where those functions are called into apply style. Therefore I was looking for some idiom like the python __call__() method, which, when present, can turn just about anything into a callable. I could change the *definition* of my original functions into apply style and the rest of the code would not notice any difference. But that does not really help, because in the end I want to Show something like [g,h,f], but my functions would no longer carry names. Alternatively I could associate functions with names in some association function, but that function simply has to know to much for my taste. The thing is, I only need the names at the very end. Throughout the majority of the computation they should stay out of the way. -- Martin ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Haskell logo
I just visited haskell.org and noticed that the old logo is back. Anybody know when/why this happened? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Thread scheduling
Control.Concurrent provides the threadDelay function, which allows you to make the current thread sleep until T=now+X. However, I can't find any way of making the current thread sleep until T=X. In other words, I want to specify an absolute wakeup time, not a relative one. What's even more frustrating is that, reading the source code, it appears that the internal RTS primitive *is* actually using an absolute time, but this isn't exposed anywhere that I can get at. Is there any danger that this could be fixed at some point? (I might also interject something about Data.Time, which seems to hardly let me do anything, but strictly that's a seperate topic...) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Haskell logo
* Andrew Coppin andrewcop...@btinternet.com [2010-06-10 18:47:23+0100] I just visited haskell.org and noticed that the old logo is back. Anybody know when/why this happened? Result of restoring from backups? -- Roman I. Cheplyaka :: http://ro-che.info/ Don't let school get in the way of your education. - Mark Twain ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] How to Show an Operation?
Hi Martin, Can you not just use trace? http://cvs.haskell.org/Hugs/pages/libraries/base/Debug-Trace.html f x = trace in f x g x = trace in g x That should show the order of evaluation. Chris. On 10 Jun 2010, at 18:44, Martin Drautzburg wrote: On Thursday, 10. June 2010 00:08:34 Luke Palmer wrote: Or just: apply = val_of So, to summarize: if you have something that isn't a function and you want to use it like a function, convert it to a function (using another function :-P). That's all. No syntax magic, just say what you're doing. Thanks Luke The reason I was asking is the following: suppose I have some code which uses some functions, and what it primarily does with those functions is CALL them in different orders. Now at a later point in time I decide I need to give names to those functions because at the end I need to print information about the functions which together solved a certain problem. Think of my problem as In which order do I have to call f,g,h such that (f.g.h) 42 = 42?. I don't want to change all places where those functions are called into apply style. Therefore I was looking for some idiom like the python __call__() method, which, when present, can turn just about anything into a callable. I could change the *definition* of my original functions into apply style and the rest of the code would not notice any difference. But that does not really help, because in the end I want to Show something like [g,h,f], but my functions would no longer carry names. Alternatively I could associate functions with names in some association function, but that function simply has to know to much for my taste. The thing is, I only need the names at the very end. Throughout the majority of the computation they should stay out of the way. -- Martin ___ 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] Using the ContT monads for early exits of IO ?
I would not use the continuation monad just for early exit. Sounds like the error monad to me. 2010/6/10 Günther Schmidt gue.schm...@web.de: Hi everyone, I'm about to write a rather lengthy piece of IO code. Depending on the results of some of the IO actions I'd like the computation to stop right there and then. Now I know in general how to write this but I'm wondering if this is one of those occasions where I should make use of the Cont monad to make an early exit. 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] Problems with threading?
There are 4 sets of rankings so - http://shootout.alioth.debian.org/u64/program.php?test=threadringlang=ghcid=3 Yes, but Haskell used to be doing much better specifically on the u64q, which was why I was surprised. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Problems with threading?
--- On Thu, 6/10/10, Louis Wasserman wasserman.lo...@gmail.com wrote: Date: Thursday, June 10, 2010, 11:25 AM There are 4 sets of rankings so - http://shootout.alioth.debian.org/u64/program.php?test=threadringlang=ghcid=3 Yes, but Haskell used to be doing much better specifically on the u64q, which was why I was surprised. I tend not to believe used to be doing much better comments until I'm shown the numbers ;-) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Problems with threading?
wasserman.louis: There are 4 sets of rankings so - http://shootout.alioth.debian.org/u64/program.php?test=threadringlang=ghc; id=3 Yes, but Haskell used to be doing much better specifically on the u64q, which was why I was surprised. Oh, indeed, http://shootout.alioth.debian.org/u64q/performance.php?test=threadring Something broke. Simon Marlow described how best to parallelize this problem extensively in: http://www.haskell.org/~simonmar/bib/multicore-ghc-09_abstract.html So I'd suggest doing what he says. In particular, use thread pinning to improve locality. -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Problems with threading?
--- On Thu, 6/10/10, Don Stewart d...@galois.com wrote: From: Don Stewart d...@galois.com Subject: Re: [Haskell-cafe] Problems with threading? To: Louis Wasserman wasserman.lo...@gmail.com Cc: igo...@yahoo.com, Haskell Café List haskell-cafe@haskell.org Date: Thursday, June 10, 2010, 11:36 AM wasserman.louis: There are 4 sets of rankings so - http://shootout.alioth.debian.org/u64/program.php?test=threadring〈=ghc; id=3 Yes, but Haskell used to be doing much better specifically on the u64q, which was why I was surprised. Oh, indeed, http://shootout.alioth.debian.org/u64q/performance.php?test=threadring Something broke. Simon Marlow described how best to parallelize this problem extensively in: http://www.haskell.org/~simonmar/bib/multicore-ghc-09_abstract.html So I'd suggest doing what he says. In particular, use thread pinning to improve locality. -qw -qm ? How's that going to work out when applied to the other Haskell programs? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: GATD and pattern matching
On Thu, Jun 10, 2010 at 11:14 PM, Daniel Fischer daniel.is.fisc...@web.dewrote: On Thursday 10 June 2010 22:01:38, Dupont Corentin wrote: Hello Maciej, i tried this out, but it didn't worked. Daniel, I added a (Show a) constraint to Equal: data Obs a where Player :: Obs Integer Turn :: Obs Integer Official :: Obs Bool Equ :: (Show a, Eq a) = Obs a - Obs a - Obs Bool --woops!! Plus :: (Num a) = Obs a - Obs a - Obs a Time :: (Num a) = Obs a - Obs a - Obs a Minus :: (Num a) = Obs a - Obs a - Obs a Konst :: a - Obs a And :: Obs Bool - Obs Bool - Obs Bool Or :: Obs Bool - Obs Bool - Obs Bool It works for the Show instance, but not Eq. By the way, shouldn't the Show constraint be on the instance and not on the datatype declaration? Can't be here, because of Equ :: Obs a - Obs a - Obs Bool You forget the parameter a, and you can't recover it in the instance declaration. So you have to provide the Show instance for a on construction, i.e. put the constraint on the data constructor. Anyway, is my Obs construction revelant at all? What i want to do is to provide an EDSL to the user to test things about the state of the game (for the Nomic game i'm making). Obs will be then embedded in another EDSL to construct Nomic's rules. I'd prefer to keep the datatype as generic as possible... There is really no way to make my Obs datatype an instance of Eq and Show?? Show can work (should with the constraint on Equ), Eq is hairy. instance Show t = Show (Obs t) where show (Equ a b) = show a ++ `Equal` ++ show b show (Plus a b) = ... show (Konst x) = Konst ++ show x ... For an Eq instance, you have the problem that Equ (Konst True) (Konst False) and Equ Player Turn both have the type Obs Bool, but have been constructed from different types, so you can't compare (Konst True) and Player. I don't see a nice way to work around that. These is a dirty way: compare the string representation of the rules. They should be unique. Corentin ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Using the ContT monads for early exits of IO ?
2010/6/10 Günther Schmidt gue.schm...@web.de: Hi everyone, I'm about to write a rather lengthy piece of IO code. Depending on the results of some of the IO actions I'd like the computation to stop right there and then. What's wrong with a mere if/else condition? foo = do bar x - mu case x of Bar - return () Mu - do y - zot case y of Zot - return () Foo - gud foo = do bar x - mu y - bar when (pred x y) $ do zot x Continuations are risky for causing confusion of readers (and the author herself), do you definitely need this? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] QuickCheck 2
Since GHC 6.12 ships with QC2 it looks like it's finally time to get around to converting some old testing scripts. Unfortunately, one of the things I couldn't figure out last time I looked (and hence why I haven't switched) is how to reconfigure the configuration parameters to the driver function. Is there a porting guide anywhere, or how else can I adjust the configuration parameters (in particular, the configMaxTest and configMaxFail parameters)? -- Live well, ~wren ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: How to Show an Operation?
On Thursday 10 June 2010 23:38:15, Martin Drautzburg wrote: On Thursday, 10. June 2010 22:10:08 Maciej Piechotka wrote: Wow! this is somewhat above my level. I guess I need to go back to the books. I'll document my ignorance nontheless. data Named a = Named String a instance Functor Named where f `fmap` (Named s v) = Named s (f v) okay so far instance Applicative Named where pure x = Named x (Named s f) * (Named t v) = Named (s ++ ( ++ t ++ )) (f v) Applicative. Need to study that Control.Applicative (*) :: Applicative f = f (a - b) - f a - f b So in our case the Applicative is a Named. Here, we define (*) for the type (*) :: (Named (a - b)) - (Named a) - (Named b) (redundant parentheses against ambiguity errors). A 'Named' thing is a thing together with a name. So how do we apply a function with a name to an argument with a name? What we get is a value with a name. The value is of course the function applied to the argument ignoring names. The name of the result is the textual representation of the function application, e.g. Named sin sin * Named pi pi ~ Named sin(pi) 1.2246063538223773e-16 (*) is application of named functions to named values, or 'lifting function application to named things'. When I apply a Named to a function, then I get a function between the corresponding Named types. When I pass it an Int-Char function, I get a Named Int - Named Char function. But here it is applied to another Named ... is that the (a-b)? Puzzeled. instance Eq a = Eq (Named a) where (Named _ x) == (Named _ y) = x == y instance Show (Named a) where show (Named s _) = s Understood. namedPure :: Show a = a - Named a namedPure x = Named (show x) x When I can show something I can always name it so its name is what 'show' would return. Okay I guess I got it. This turns a showable into a Named. test :: Num a = (a - a) - (a - a) - (a - a) - [String] test f g h = do [f', g', h'] - permutations [Named f f, Named g g, Named h h] According to Hoogle permutations should be in Data.List. Mine (GHCI 6.8.2) does not seem to have it. Seems to have something to do with Upgrade. We're at 6.12 now! Lots of improvements. permutations was added in 6.10, IIRC. base, whatever that is. guard $ namedPure 42 == f' * g' * h' * namedPure 42 Ah, the 42 needs namedPure. Simplest way, it could be Named answer to Life, the Universe and Everything 42 Again this * operator... I believe the whole thing is using a List Monad. return $ show f' ++ . ++ show g' ++ . ++ show h' I wonder if the thing returns just one string or a list of strings. I A list, one string for every permutation satisfying the condition. guess return cannot return anything more unwrapped than a List, so it must be a List. But does it contain just the first match or all of them? All of them! And how many brackets are around them? do x - list guard (condition x) return (f x) is syntactic sugar for concat (map (\x - if condition x then [f x] else []) list) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] QuickCheck 2
wren ng thornton wrote: Since GHC 6.12 ships with QC2 it looks like it's finally time to get around to converting some old testing scripts. Unfortunately, one of the things I couldn't figure out last time I looked (and hence why I haven't switched) is how to reconfigure the configuration parameters to the driver function. Is there a porting guide anywhere, or how else can I adjust the configuration parameters (in particular, the configMaxTest and configMaxFail parameters)? Ah, nevermind. I found what they renamed things to -- Live well, ~wren ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Using the ContT monads for early exits of IO ?
Actually, on second thought, Lennart is probably right. Continuations are probably overkill for this situation. Since not wanting to continue is probably an 'erroneous condition,' you may as well use Error. Cheers, - Tim 2010/6/10 Lennart Augustsson lenn...@augustsson.net I would not use the continuation monad just for early exit. Sounds like the error monad to me. 2010/6/10 Günther Schmidt gue.schm...@web.de: Hi everyone, I'm about to write a rather lengthy piece of IO code. Depending on the results of some of the IO actions I'd like the computation to stop right there and then. Now I know in general how to write this but I'm wondering if this is one of those occasions where I should make use of the Cont monad to make an early exit. 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 ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] QuickCheck 2
wren ng thornton w...@freegeek.org writes: Since GHC 6.12 ships with QC2 it looks like it's finally time to get around to converting some old testing scripts. Well, the Haskell Platform does, not GHC... Unfortunately, one of the things I couldn't figure out last time I looked (and hence why I haven't switched) is how to reconfigure the configuration parameters to the driver function. Is there a porting guide anywhere, or how else can I adjust the configuration parameters (in particular, the configMaxTest and configMaxFail parameters)? I'm not sure what you mean by driver function, but there is quickCheckWith: http://hackage.haskell.org/packages/archive/QuickCheck/2.1.0.3/doc/html/Test-QuickCheck.html#v%3AquickCheckWith (and also quickCheckWithResult) which let you customise the number of tests you want, etc. Is that what you were after? -- 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] Re: GATD and pattern matching
Hello Maciej, i tried this out, but it didn't worked. Daniel, I added a (Show a) constraint to Equal: data Obs a where Player :: Obs Integer Turn :: Obs Integer Official :: Obs Bool Equ :: (Show a, Eq a) = Obs a - Obs a - Obs Bool --woops!! Plus :: (Num a) = Obs a - Obs a - Obs a Time :: (Num a) = Obs a - Obs a - Obs a Minus :: (Num a) = Obs a - Obs a - Obs a Konst :: a - Obs a And :: Obs Bool - Obs Bool - Obs Bool Or :: Obs Bool - Obs Bool - Obs Bool It works for the Show instance, but not Eq. By the way, shouldn't the Show constraint be on the instance and not on the datatype declaration? I'd prefer to keep the datatype as generic as possible... There is really no way to make my Obs datatype an instance of Eq and Show?? I searched around a way to add type information on the pattern match like: instance Show t = Show (Obs t) where show (Equal (a::Obs t) (b::Obs t)) = (show a) ++ Equal ++ (show b) show (Plus a b) = (show a) ++ Plus ++ (show b) But it doesn't work. thanks for your help, Corentin On Thu, Jun 10, 2010 at 2:47 AM, Maciej Piechotka uzytkown...@gmail.comwrote: On Wed, 2010-06-09 at 22:28 +0200, Dupont Corentin wrote: Thanks for your response. How would you do it? I design this GATD for a game i'm making: data Obs a where Player :: Obs Integer Turn :: Obs Integer Official :: Obs Bool Equ :: Obs a - Obs a - Obs Bool --woops!! Plus :: (Num a) = Obs a - Obs a - Obs a Time :: (Num a) = Obs a - Obs a - Obs a Minus :: (Num a) = Obs a - Obs a - Obs a Konst :: a - Obs a Actually woops is here. Make it for example Const :: (Show a, Eq a, ...) = a - Obs a And :: Obs Bool - Obs Bool - Obs Bool Or :: Obs Bool - Obs Bool - Obs Bool For example I can design an Observable like that: myObs = Player `Equ` (Konst 1) `And` Official These Observables will then be processed during gameplay. I would like to be able to do in ghci: show myObs Player `Equ` (Konst 1) `And` Official and: myObs == myObs True Regards ___ 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] Problems with threading?
--- On Thu, 6/10/10, Don Stewart d...@galois.com wrote: From: Don Stewart d...@galois.com Subject: Re: [Haskell-cafe] Problems with threading? To: Isaac Gouy igo...@yahoo.com Cc: Louis Wasserman wasserman.lo...@gmail.com, Haskell Café List haskell-cafe@haskell.org Date: Thursday, June 10, 2010, 12:54 PM igouy2: Simon Marlow described how best to parallelize this problem extensively in: http://www.haskell.org/~simonmar/bib/multicore-ghc-09_abstract.html So I'd suggest doing what he says. In particular, use thread pinning to improve locality. -qw -qm ? How's that going to work out when applied to the other Haskell programs? I'm sure it does bad things to them. Yep, earlier in the week I measured the programs using +RTS -N4 -qw -qm which is why I wonder how you would approach programs that have a mix of performance characteristics? Maybe there aren't large Haskell programs like that? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Using the ContT monads for early exits of IO ?
Yeah, I might actually prefer calling it EitherT instead of ErrorT. It doesn't have to be used for error, it's just what it is most often used for. - Job On Thu, Jun 10, 2010 at 3:57 PM, Maciej Piechotka uzytkown...@gmail.comwrote: On Thu, 2010-06-10 at 14:09 -0500, Tim Wawrzynczak wrote: Actually, on second thought, Lennart is probably right. Continuations are probably overkill for this situation. Since not wanting to continue is probably an 'erroneous condition,' you may as well use Error. Cheers, - Tim Technically it can be a success. For example if we get a list of HostInfo for given hostname we want to connect once instead of many times. Also the first time might not succeed (it is entry in IPv4 network). Error monad seems not to be a semantic solution as we exit on success not failure. Regards ___ 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: Using the ContT monads for early exits of IO ?
On Thu, Jun 10, 2010 at 8:57 PM, Maciej Piechotka uzytkown...@gmail.com wrote: Error monad seems not to be a semantic solution as we exit on success not failure. Which is really why the Either monad should not necessarily have Error associations :) If you forget about the fail method, the Monad (Either e) instance doesn't need the e to be an error type. Alternatively, if even Error is more information than you need, you could use MaybeT: http://hackage.haskell.org/package/MaybeT which allows you to just stop. Given you're using it with IO it'd be easy to write a result to an IORef before terminating the computation, so it's of equivalent power, if slightly less convenient. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Problems with threading?
igouy2: In particular, use thread pinning to improve locality. -qw -qm ? How's that going to work out when applied to the other Haskell programs? I'm sure it does bad things to them. Yep, earlier in the week I measured the programs using +RTS -N4 -qw -qm which is why I wonder how you would approach programs that have a mix of performance characteristics? Maybe there aren't large Haskell programs like that? Partioning different parallel components of the application has been studied in large scale systems. I'm not aware of work done on this in Haskell yet. If different phases of a algorithm need to use more or less parallelism, that's certainly a lot easier (mixtures of forkOnIO and (forkIO or par)). -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] QuickCheck 2
Ivan Lazar Miljenovic wrote: wren ng thornton w...@freegeek.org writes: Since GHC 6.12 ships with QC2 it looks like it's finally time to get around to converting some old testing scripts. Well, the Haskell Platform does, not GHC... Fair enough (it was one of the two :) Unfortunately, one of the things I couldn't figure out last time I looked (and hence why I haven't switched) is how to reconfigure the configuration parameters to the driver function. Is there a porting guide anywhere, or how else can I adjust the configuration parameters (in particular, the configMaxTest and configMaxFail parameters)? I'm not sure what you mean by driver function, but there is quickCheckWith: http://hackage.haskell.org/packages/archive/QuickCheck/2.1.0.3/doc/html/Test-QuickCheck.html#v%3AquickCheckWith (and also quickCheckWithResult) which let you customise the number of tests you want, etc. Is that what you were after? Yeah, that's the one. -- Live well, ~wren ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: GATD and pattern matching
On Thursday 10 June 2010 22:01:38, Dupont Corentin wrote: Hello Maciej, i tried this out, but it didn't worked. Daniel, I added a (Show a) constraint to Equal: data Obs a where Player :: Obs Integer Turn :: Obs Integer Official :: Obs Bool Equ :: (Show a, Eq a) = Obs a - Obs a - Obs Bool --woops!! Plus :: (Num a) = Obs a - Obs a - Obs a Time :: (Num a) = Obs a - Obs a - Obs a Minus :: (Num a) = Obs a - Obs a - Obs a Konst :: a - Obs a And :: Obs Bool - Obs Bool - Obs Bool Or :: Obs Bool - Obs Bool - Obs Bool It works for the Show instance, but not Eq. By the way, shouldn't the Show constraint be on the instance and not on the datatype declaration? Can't be here, because of Equ :: Obs a - Obs a - Obs Bool You forget the parameter a, and you can't recover it in the instance declaration. So you have to provide the Show instance for a on construction, i.e. put the constraint on the data constructor. I'd prefer to keep the datatype as generic as possible... There is really no way to make my Obs datatype an instance of Eq and Show?? Show can work (should with the constraint on Equ), Eq is hairy. instance Show t = Show (Obs t) where show (Equ a b) = show a ++ `Equal` ++ show b show (Plus a b) = ... show (Konst x) = Konst ++ show x ... For an Eq instance, you have the problem that Equ (Konst True) (Konst False) and Equ Player Turn both have the type Obs Bool, but have been constructed from different types, so you can't compare (Konst True) and Player. I don't see a nice way to work around that. I searched around a way to add type information on the pattern match like: instance Show t = Show (Obs t) where show (Equal (a::Obs t) (b::Obs t)) = (show a) ++ Equal ++ (show b) show (Plus a b) = (show a) ++ Plus ++ (show b) But it doesn't work. thanks for your help, Corentin ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Using the ContT monads for early exits of IO ?
Hi Christopher, there is nothing wrong with ifs as such except the won't actually exit a long piece of code, the computation will continue, just in a useless way. Primarily for every if I need two forks, so at every if the branches double. I have written the previous code with ifs and it's quite spaghetti-ish and I hope that using callCC here helps to avoid it. Of course there is no guarantee that it actually will. ;) Günther ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: How to Show an Operation?
On Thu, 2010-06-10 at 19:44 +0200, Martin Drautzburg wrote: On Thursday, 10. June 2010 00:08:34 Luke Palmer wrote: Or just: apply = val_of So, to summarize: if you have something that isn't a function and you want to use it like a function, convert it to a function (using another function :-P). That's all. No syntax magic, just say what you're doing. Thanks Luke The reason I was asking is the following: suppose I have some code which uses some functions, and what it primarily does with those functions is CALL them in different orders. Now at a later point in time I decide I need to give names to those functions because at the end I need to print information about the functions which together solved a certain problem. Think of my problem as In which order do I have to call f,g,h such that (f.g.h) 42 = 42?. I don't want to change all places where those functions are called into apply style. Therefore I was looking for some idiom like the python __call__() method, which, when present, can turn just about anything into a callable. I could change the *definition* of my original functions into apply style and the rest of the code would not notice any difference. But that does not really help, because in the end I want to Show something like [g,h,f], but my functions would no longer carry names. Alternatively I could associate functions with names in some association function, but that function simply has to know to much for my taste. The thing is, I only need the names at the very end. Throughout the majority of the computation they should stay out of the way. data Named a = Named String a instance Functor Named where f `fmap` (Named s v) = Named s (f v) instance Applicative Named where pure x = Named x (Named s f) * (Named t v) = Named (s ++ ( ++ t ++ )) (f v) instance Eq a = Eq (Named a) where (Named _ x) == (Named _ y) = x == y instance Show (Named a) where show (Named s _) = s namedPure :: Show a = a - Named a namedPure x = Named (show x) x test :: Num a = (a - a) - (a - a) - (a - a) - [String] test f g h = do [f', g', h'] - permutations [Named f f, Named g g, Named h h] guard $ namedPure 42 == f' * g' * h' * namedPure 42 return $ show f' ++ . ++ show g' ++ . ++ show h' (code is not tested but it should work) Regards signature.asc Description: This is a digitally signed message part ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Problems with threading?
igouy2: Simon Marlow described how best to parallelize this problem extensively in: http://www.haskell.org/~simonmar/bib/multicore-ghc-09_abstract.html So I'd suggest doing what he says. In particular, use thread pinning to improve locality. -qw -qm ? How's that going to work out when applied to the other Haskell programs? I'm sure it does bad things to them. -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Using the ContT monads for early exits of IO ?
On Thu, 2010-06-10 at 14:09 -0500, Tim Wawrzynczak wrote: Actually, on second thought, Lennart is probably right. Continuations are probably overkill for this situation. Since not wanting to continue is probably an 'erroneous condition,' you may as well use Error. Cheers, - Tim Technically it can be a success. For example if we get a list of HostInfo for given hostname we want to connect once instead of many times. Also the first time might not succeed (it is entry in IPv4 network). Error monad seems not to be a semantic solution as we exit on success not failure. Regards signature.asc Description: This is a digitally signed message part ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Using the ContT monads for early exits of IO ?
Lennart Augustsson wrote: I would not use the continuation monad just for early exit. Sounds like the error monad to me. I.e., the Either/ErrorT monad. But the mtl/transformers packages have an orphan instance for Either that requires the exit type to be an instance of the Error class. If that doesn't work in your case, use the Exit monad: http://www.haskell.org/haskellwiki/New_monads/MonadExit Or use the Maybe monad written additively, i.e. mplus in place of (more or less). Regards, Yitz ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: How to Show an Operation?
On Thursday, 10. June 2010 22:10:08 Maciej Piechotka wrote: Wow! this is somewhat above my level. I guess I need to go back to the books. I'll document my ignorance nontheless. data Named a = Named String a instance Functor Named where f `fmap` (Named s v) = Named s (f v) okay so far instance Applicative Named where pure x = Named x (Named s f) * (Named t v) = Named (s ++ ( ++ t ++ )) (f v) Applicative. Need to study that Control.Applicative (*) :: Applicative f = f (a - b) - f a - f b So in our case the Applicative is a Named. When I apply a Named to a function, then I get a function between the corresponding Named types. When I pass it an Int-Char function, I get a Named Int - Named Char function. But here it is applied to another Named ... is that the (a-b)? Puzzeled. instance Eq a = Eq (Named a) where (Named _ x) == (Named _ y) = x == y instance Show (Named a) where show (Named s _) = s Understood. namedPure :: Show a = a - Named a namedPure x = Named (show x) x When I can show something I can always name it so its name is what 'show' would return. Okay I guess I got it. This turns a showable into a Named. test :: Num a = (a - a) - (a - a) - (a - a) - [String] test f g h = do [f', g', h'] - permutations [Named f f, Named g g, Named h h] According to Hoogle permutations should be in Data.List. Mine (GHCI 6.8.2) does not seem to have it. Seems to have something to do with base, whatever that is. guard $ namedPure 42 == f' * g' * h' * namedPure 42 Ah, the 42 needs namedPure. Again this * operator... I believe the whole thing is using a List Monad. return $ show f' ++ . ++ show g' ++ . ++ show h' I wonder if the thing returns just one string or a list of strings. I guess return cannot return anything more unwrapped than a List, so it must be a List. But does it contain just the first match or all of them? All of them! And how many brackets are around them? -- Martin ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: GATD and pattern matching
On Thu, Jun 10, 2010 at 11:14:42PM +0200, Daniel Fischer wrote: Show can work (should with the constraint on Equ), Eq is hairy. instance Show t = Show (Obs t) where show (Equ a b) = show a ++ `Equal` ++ show b show (Plus a b) = ... show (Konst x) = Konst ++ show x ... For an Eq instance, you have the problem that Equ (Konst True) (Konst False) and Equ Player Turn both have the type Obs Bool, but have been constructed from different types, so you can't compare (Konst True) and Player. I don't see a nice way to work around that. I didn't test, but something like this could work: Equ :: (Show a, Eq a, Typeable a) = Obs a - Obs a - Obs Bool (Equ a b) == (Equ c d) = eqTypeable (a,b) (c,d) eqTypeable :: (Typeable a, Eq a, Typeable b, Eq b) = a - b - Bool eqTypeable x y = case cast y of Just y' - x == y' Nothing - False Maybe not ;). Cheers, -- Felipe. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Using the ContT monads for early exits of IO ?
Or what about a specialized Escape Continuation monad? (Perhaps there is one on hackage, not sure). Something that allows you to set up an continuation (for escape) purposes, but does not allow you to capture any more continuations after that, and call that escape cont w/in itself, supplying a return value. i.e. run = do result - createEscape $ \escape - lengthyComputation1 inp - askToContinue if (not (continue inp)) then escape They quit else lengthyComputation2 return result Just thinking off the top of my head :). However, if there are going to be multiple 'lengthy computations' then perhaps MaybeT or EitherT would be better, b/c they allow the propagation of failure across multiple actions, instead of cascading off to the right of the screen w/ 'if's or 'case's. Cheers, - Tim On Thu, Jun 10, 2010 at 3:21 PM, Ben Millwood hask...@benmachine.co.ukwrote: On Thu, Jun 10, 2010 at 8:57 PM, Maciej Piechotka uzytkown...@gmail.com wrote: Error monad seems not to be a semantic solution as we exit on success not failure. Which is really why the Either monad should not necessarily have Error associations :) If you forget about the fail method, the Monad (Either e) instance doesn't need the e to be an error type. Alternatively, if even Error is more information than you need, you could use MaybeT: http://hackage.haskell.org/package/MaybeT which allows you to just stop. Given you're using it with IO it'd be easy to write a result to an IORef before terminating the computation, so it's of equivalent power, if slightly less convenient. ___ 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: bytestring-trie 0.2.2 (major bugfix)
-- bytestring-trie 0.2.2 (major bugfix) Another release for efficient finite maps from (byte)strings to values. This version corrects a major bug affecting all users who merge tries. -- Changes (since 0.1.4) * Corrected a major bug in mergeBy which caused conflicting values to be merged in the wrong order. Since this is a core function, all other merging-based functions are affected as well (e.g., unionR, unionL,...). The bug was filed by Gregory Crosswhite (thanks!). * added Data.Trie.Convenience.fromListWith --- A variant of 'fromListR' that takes a function for combining values on conflict. * generalized the type of toListBy * removed KeyString and KeyElem aliases * documentation tweaks -- Future work * Worked on explicit definitions for foldl and foldr, as opposed to the default definitions given by Foldable using Endo. The suggested definitions are around 3x faster than the old definitions, however the order of folding is different than foldrWithKey (which seems to have the correct order). These definitions are not currently being used, but perhaps the future will see faster folding functions for Tries. -- Links Homepage: http://code.haskell.org/~wren/ Hackage: http://hackage.haskell.org/package/bytestring-trie Darcs: http://community.haskell.org/~wren/bytestring-trie/ Haddock (Darcs version): http://community.haskell.org/~wren/bytestring-trie/dist/doc/html/bytestring-trie/ -- Live well, ~wren ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Using the ContT monads for early exits of IO ?
Or... one could just use the exceptions that are already built into the IO monad... 2010/6/10 Yitzchak Gale g...@sefer.org: Lennart Augustsson wrote: I would not use the continuation monad just for early exit. Sounds like the error monad to me. I.e., the Either/ErrorT monad. But the mtl/transformers packages have an orphan instance for Either that requires the exit type to be an instance of the Error class. If that doesn't work in your case, use the Exit monad: http://www.haskell.org/haskellwiki/New_monads/MonadExit Or use the Maybe monad written additively, i.e. mplus in place of (more or less). Regards, Yitz ___ 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] Using the ContT monads for early exits of IO ?
On Thu, Jun 10, 2010 at 8:45 PM, Derek Elkins derek.a.elk...@gmail.comwrote: Or... one could just use the exceptions that are already built into the IO monad... It feels to me like this discussion has a lot of speculation in it. I would like to see concrete examples of the code and the suggested improvements. 2010/6/10 Yitzchak Gale g...@sefer.org: Lennart Augustsson wrote: I would not use the continuation monad just for early exit. Sounds like the error monad to me. I.e., the Either/ErrorT monad. But the mtl/transformers packages have an orphan instance for Either that requires the exit type to be an instance of the Error class. If that doesn't work in your case, use the Exit monad: http://www.haskell.org/haskellwiki/New_monads/MonadExit Or use the Maybe monad written additively, i.e. mplus in place of (more or less). Regards, Yitz ___ 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
Re: [Haskell-cafe] Re: How to Show an Operation?
On Jun 10, 2010, at 17:38 , Martin Drautzburg wrote: instance Applicative Named where pure x = Named x (Named s f) * (Named t v) = Named (s ++ ( ++ t ++ )) (f v) Applicative. Need to study that The above is just the Functor, rephrased in Applicative style. * is exactly fmap. Likewise, Monad has a function liftM which is exactly fmap. (For historical reasons, these are not related the way they should be: all Monads should be Applicatives, all Applicatives should be Functors, and all Functors should be instances of an even more primitive class Pointed.) According to Hoogle permutations should be in Data.List. Mine (GHCI 6.8.2) does not seem to have it. Seems to have something to do with base, whatever that is. Things have gradually been moving out of base; you probably need to install containers from Hackage. -- brandon s. allbery [solaris,freebsd,perl,pugs,haskell] allb...@kf8nh.com system administrator [openafs,heimdal,too many hats] allb...@ece.cmu.edu electrical and computer engineering, carnegie mellon universityKF8NH PGP.sig Description: This is a digitally signed message part ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Thread scheduling
On Thu, Jun 10, 2010 at 11:50 AM, Andrew Coppin andrewcop...@btinternet.com wrote: Control.Concurrent provides the threadDelay function, which allows you to make the current thread sleep until T=now+X. However, I can't find any way of making the current thread sleep until T=X. In other words, I want to specify an absolute wakeup time, not a relative one. Modulo a small epsilon between the two actions, can't you just get the current time and subtract it from the target time? threadDelay is allowed to delay for too long anyway, so doing it this way does not lose you any correctness. Luke ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Thread scheduling
Say, using System.Time.getClockTime. Luke On Thu, Jun 10, 2010 at 11:31 PM, Luke Palmer lrpal...@gmail.com wrote: On Thu, Jun 10, 2010 at 11:50 AM, Andrew Coppin andrewcop...@btinternet.com wrote: Control.Concurrent provides the threadDelay function, which allows you to make the current thread sleep until T=now+X. However, I can't find any way of making the current thread sleep until T=X. In other words, I want to specify an absolute wakeup time, not a relative one. Modulo a small epsilon between the two actions, can't you just get the current time and subtract it from the target time? threadDelay is allowed to delay for too long anyway, so doing it this way does not lose you any correctness. Luke ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: How to Show an Operation?
On Thu, Jun 10, 2010 at 10:43 PM, Brandon S. Allbery KF8NH allb...@ece.cmu.edu wrote: On Jun 10, 2010, at 17:38 , Martin Drautzburg wrote: instance Applicative Named where pure x = Named x (Named s f) * (Named t v) = Named (s ++ ( ++ t ++ )) (f v) Applicative. Need to study that The above is just the Functor, rephrased in Applicative style. * is exactly fmap. Likewise, Monad has a function liftM which is exactly fmap. (For historical reasons, these are not related the way they should be: all Monads should be Applicatives, all Applicatives should be Functors, and all Functors should be instances of an even more primitive class Pointed.) (*) :: Applicative f = f (a - b) - f a - f b ($) :: Functor f = (a - b) - f a - f b ($) is fmap, not (*). (*) is available for monads as Control.Monad.ap. Luke ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: How to Show an Operation?
On Friday, 11. June 2010 00:12:03 Daniel Fischer wrote: Thanks Daniel. Upgrade. We're at 6.12 now! Did that. Everything is available now. I am still having trouble with the test function. First it seems I need braces, so I can mix == and *. test :: Num a = (a - a) - (a - a) - (a - a) - [String] test f g h = do [f', g', h'] - permutations [Named f f, Named g g, Named h h] guard $ namedPure 42 == (f' * g' * h' * namedPure 42) return $ show f' ++ . ++ show g' ++ . ++ show h' But this leads to Occurs check: cannot construct the infinite type: a = (a - a) - a1 - t When generalising the type(s) for `test' This error message is still the maximum penalty for me (along with Corba marshall exception in J2EE and Missing right parenthesis in Oracle SQL) Then generally speaking, I have the feeling that this code does not allow namifying existing code either. In this respect it does not seem to do better than the apply method pattern discussed earlier in this thread. The problem it solves is very simple and therefore using (*) and namedPure isn't much of a drawback. But if I had tons of code to namify I would still have to do significant changes to it, right? -- Martin ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
