On 15 October 2010 07:53, Mihai Maruseac mihai.marus...@gmail.com wrote:
Hi,
Is there a way to determine the order in which thunks are created and
expanded/evaluated in Haskell (GHC)? I'm looking mainly at some
existing interface but if there is only something in the GHC source it
will
Michael Snoyman wrote:
I have a recommendation of how to fix this: the MonadCatchIO typeclass
should be extended to include finally, onException and everything
else. We can provide default definitions which will work for most
monads, and short-circuiting monads like ErrorT (and I imagine
On Fri, Oct 15, 2010 at 9:35 AM, o...@okmij.org wrote:
Michael Snoyman wrote:
I have a recommendation of how to fix this: the MonadCatchIO typeclass
should be extended to include finally, onException and everything
else. We can provide default definitions which will work for most
monads,
On Thu, 2010-10-14 at 17:45 +, Johannes Waldmann wrote:
Hi. I wonder how to do the following properly.
I have one (large) C type, let's call it T,
and I want to sell it as an abstract type in Haskell.
I want to use C functions as if they were of type T - T
(pure function, returns a
Michael Snoyman wrote:
I would prefer if the test read as:
test33 = fmap (== Left throwError) $ test3c (throwError throwError ::
ErrorT String IO String)
Which never in fact returns True. Or, more to the point, the test is
never even called, since the runtime exception prevents it.
On Fri, Oct 15, 2010 at 10:22 AM, o...@okmij.org wrote:
Michael Snoyman wrote:
I would prefer if the test read as:
test33 = fmap (== Left throwError) $ test3c (throwError throwError ::
ErrorT String IO String)
Which never in fact returns True. Or, more to the point, the test is
never
I needed GHC on a new machine, and went to download a binary tarball.
First, I go to http://haskell.org/ghc/download_ghc_6_12_3.html,
which kindly suggests to get the Haskell Platform instead.
Then, at http://hackage.haskell.org/platform/linux.html, I'm told that I
first need GHC, and pointed
Bernie Pope florbit...@gmail.com writes:
You can use side effects to observe the order of evaluation, by
wrapping observed expressions (thunks) with some IO computation inside
unsafePerformIO.
Not what OP asks for, but I've used a variant of this as a rather
hackish to provide progress
Duncan Coutts duncan.coutts at googlemail.com writes:
It is exactly for this purpose that the Haskell FFI library includes
unsafePerformIO. This is basically *the* legitimate use case for it, so
you don't need to feel bad about it.
OK, thanks. Then this means my C type is a ForeignPtr,
and
Thanks Brandon!
I really like the addParam utility,
value val prompt = Question prompt (show val) (readCheck val)
addParam :: (Show a) = (funTy - String - qty) - (a - funTy) -
String - (a
- qty)
addParam qmakr fun string v = qmakr (fun v) (string++ ++show v)
prefix1 = addParam value
Uwe Schmidt wrote:
In HXT, the concept of a filter is the most important one. This
concept is a natural generalisation of a function (and that's what
arrows are). A user has to grasp this idea of a filter. And he/she
can do this even without knowing anything about arrows or monads.
People
Jacek,
I haven't been following this thread in any detail, so I apologise if
I misunderstand your goal, but the ctm function in the polyToMonoid
library (which maps its parameters to any specified monoid) appears to
work in just this way.
It keeps consuming parameters until you hand it to the
On 2010 Oct 15, at 11:53, Kevin Jardine wrote:
Jacek,
I haven't been following this thread in any detail, so I apologise if
I misunderstand your goal,
My goal (in this thread, at least) is to become a better Haskell
programmer, rather than to actually write any specific program. Yes,
On 15 Oct 2010, at 10:44, Heinrich Apfelmus wrote:
Personally, I would be much happier with the slogan HXT = XML
transformations with filters. Browsing through Manuel's thesis, I
discover that your combinators are quite slick ( , choiceA , when,
guards ), it's just that they are a very
Using Brandon's code as a starting point (as it's far neater than
mine), let's try asking some questions about fractions (I've included
the whole program at the end).
questions = [ addition 1 2, addition (1%2) (1%3) ]
This works, but the the fractions are shown as 1 % 2 and to make it
On 2010 Oct 15, at 13:32, Jacek Generowicz wrote:
questions = [ addition 1 2, addition (1%2) (1%3) ]
My problem is that I don't see where I could add a type signature,
but still keep
addition :: a - a - Question
polymorphic.
Well, OK, I could write
addition 1 (2 :: Int)
hi all,
i am working on an application that evaluates haskell code entered by the user
using the plugins package [1]; now i want to deploy the application as a
self-contained .app bundle on OSX, i.e. the end user should not have to install
anything in addition.
what do i need to bundle in order
Hi -
How can I generate all binary string of a given length? The type
signature would something like -
genbin :: Int - [String]
For example genbin 2 would give [00,11,01,10] and genbin 3
would give [000,001,010,011,100,101,110,111] etc..
thanks..
___
genbin = flip replicateM 01
2010/10/15 rgowka1 rgow...@gmail.com:
Hi -
How can I generate all binary string of a given length? The type
signature would something like -
genbin :: Int - [String]
For example genbin 2 would give [00,11,01,10] and genbin 3
would give
Here's why it works:
genbin 3 = replicateM 3 01 = (unfold replicateM) do x1 - 01; x2
- 01 ; x3 - 01; return [x1,x2,x3] = your desired result
(enumerate all combinations of x1,x2,x3 with each being 0 or 1).
2010/10/15 Eugene Kirpichov ekirpic...@gmail.com:
genbin = flip replicateM 01
On Fri, 15 Oct 2010 09:07:22 +0100, Duncan Coutts
duncan.cou...@googlemail.com wrote:
On Thu, 2010-10-14 at 17:45 +, Johannes Waldmann wrote:
Hi. I wonder how to do the following properly.
I have one (large) C type, let's call it T,
and I want to sell it as an abstract type in
Not the most efficient, but easy to understand:
genbin 0 = []
genbin 1 = [0, 1]
genbin i =
map ('0' :) x ++ map ('1' :) x
where
x = genbin $ i - 1
On Fri, Oct 15, 2010 at 2:21 PM, rgowka1 rgow...@gmail.com wrote:
Hi -
How can I generate all binary string of a given length? The type
Amazing, will never find this in any other languagw. But ghci crashes
for bigger input. Like genbin 20. How to scale this function?
On 10/15/10, Eugene Kirpichov ekirpic...@gmail.com wrote:
Here's why it works:
genbin 3 = replicateM 3 01 = (unfold replicateM) do x1 - 01; x2
- 01 ; x3 - 01;
On Fri, 15 Oct 2010 14:34:42 +0200, rgowka1 rgow...@gmail.com wrote:
Amazing, will never find this in any other languagw. But ghci crashes
for bigger input. Like genbin 20. How to scale this function?
Well, scaling this isn't really possible, because of its complexity. It
generates all
Actually my ghci doesn't crash for genbin 25 (haven't tried further),
though it eats quite a bit of memory.
How are you going to use these bit strings? Do you need all of them at once?
2010/10/15 Aleksandar Dimitrov aleks.dimit...@googlemail.com:
On Fri, 15 Oct 2010 14:34:42 +0200, rgowka1
I trying to learn a bit about data parallel haskell, and started from the
wiki page here: http://www.haskell.org/haskellwiki/GHC/Data_Parallel_Haskell.
Two questions:
The examples express the dot product as:
dotp_double xs ys = sumP [:x *
Michael,
The package Workflow has persistent timeouts (can wait for years and
restart on system failure if embedded in the workflow monad, although
it can run in the IO monad, with no recovery). They are composable
with any action in the STM monad with orElse:
flag - getTimeoutFlag $
I expect this one to run in constant space:
import Data.Bits
genbin :: Int - [String]
genbin n = map (showFixed n) [0..2^n-1::Int]
where showFixed n i = map (bool '1' '0' . testBit i) [n-1,n-2..0]
bool t f b = if b then t else f
Daniel
On Oct 15, 2010, at 9:43 AM, Eugene
Thanks Daniel.
But genbin 32 gives an empty list.. works till 31.
On Fri, Oct 15, 2010 at 9:05 AM, Daniel Gorín dgo...@dc.uba.ar wrote:
I expect this one to run in constant space:
import Data.Bits
genbin :: Int - [String]
genbin n = map (showFixed n) [0..2^n-1::Int]
where showFixed n i
On Fri, 15 Oct 2010 09:16:58 -0400, rgowka1 rgow...@gmail.com wrote:
But genbin 32 gives an empty list.. works till 31.
That's because Daniel uses values of type Int as intermediate storage
during the computation, and Int values are only 32 bits long. By
replacing Int with Integer (which does
I trying to learn a bit about data parallel haskell, and started from the
wiki page here:http://www.haskell.org/haskellwiki/GHC/Data_Parallel_Haskell.
Two questions:
The examples express the dot product as:
dotp_double xs ys = sumP [:x *
On Friday 15 October 2010 14:59:18, Warren Harris wrote:
I trying to learn a bit about data parallel haskell, and started from
the wiki page here:
http://www.haskell.org/haskellwiki/GHC/Data_Parallel_Haskell. Two
questions:
The examples express the dot product as:
dotp_double xs ys = sumP
Got it - thanks. Any idea about the run-away process problem? Thanks,
Warren
On Fri, Oct 15, 2010 at 9:32 AM, Daniel Fischer daniel.is.fisc...@web.dewrote:
On Friday 15 October 2010 14:59:18, Warren Harris wrote:
I trying to learn a bit about data parallel haskell, and started from
the
On 2010 Oct 15, at 11:38, Jacek Generowicz wrote:
[...]
So I'm trying to get to grips with a simpler variation on the same
theme, and I'm still failing. I'm trying to write something along
the lines of
addArg :: nArgFn - a - nPlus1ArgFn
addArg fn a = (a+) fn where
=
The darcs team would like to announce the immediate availability of darcs 2.5
release candidate 1 (also known as darcs 2.4.99.1 due to Cabal restrictions).
If no blocking issues are found in the coming week, we will finally releease
darcs 2.5.
Important changes since darcs 2.4.4 are:
*
ketil:
I needed GHC on a new machine, and went to download a binary tarball.
First, I go to http://haskell.org/ghc/download_ghc_6_12_3.html,
which kindly suggests to get the Haskell Platform instead.
Then, at http://hackage.haskell.org/platform/linux.html, I'm told that I
first need
* Henning Thielemann:
Some open/close pairs have corresponding 'with' functions, that are
implemented using Exception.bracket. You can also use them within
GHCi. I think using both manual resource deallocation and finalizers
makes everything more complicated and more unreliable.
It seems
15.10.2010 15:03, Malcolm Wallace пишет:
On 15 Oct 2010, at 10:44, Heinrich Apfelmus wrote:
Personally, I would be much happier with the slogan HXT = XML
transformations with filters. Browsing through Manuel's thesis, I
discover that your combinators are quite slick ( , choiceA , when,
The latter. atomicModifyIORef is harder though still, since it is a
primop with the same properties as modifyIORef :/
So would it make sense to create a strict modifyIORef' function?
Very much so. In fact, I'd argue the vast majority of uses are for the
WHNF-strict version.
I just fixed a
On Fri, Oct 15, 2010 at 11:09 AM, Florian Weimer f...@deneb.enyo.de wrote:
* Henning Thielemann:
Some open/close pairs have corresponding 'with' functions, that are
implemented using Exception.bracket. You can also use them within
GHCi. I think using both manual resource deallocation and
Don Stewart d...@galois.com writes:
First, I go to http://haskell.org/ghc/download_ghc_6_12_3.html,
which kindly suggests to get the Haskell Platform instead.
Then, at http://hackage.haskell.org/platform/linux.html, I'm told that I
first need GHC, and pointed back to the GHC download page.
Don Stewart d...@galois.com writes:
Linux users don't have easy binary installers, usually.
Speaking about which - this is made a lot more difficult than it need be
due to the way libc doesn't work with statically linked executables.
Basically, it seems to manually load hardwired dynamic
On Fri, Oct 15, 2010 at 1:47 PM, Ketil Malde ke...@malde.org wrote:
Uh, AFAIC, it's only a documentation bug - the GHC page seems to say
that GHC comes with HP, the HP page tells to go get GHC first. I'd just
change it to something like:
GHC: Click here to download... then go see Haskell
http://k1024.org/~iusty/papers/icfp10-haskell-reagent.pdf
I'm sure some of you have seen this already. For those who lack the time
or inclination to read through the (six) pages of this report, here's
the summary...
We [i.e., the report authors] took a production Python system and
rewrote
Evan Laforge qdun...@gmail.com writes:
The only workaround I could find is to immediately read the value back
out and 'seq' on it, but it's ugly.
Yep! C'est la vie unfortunately.
The way atomicModifyIORef works is that the new value isn't actually
evaluated at all; GHC just swaps the old
Yesterday I read a rather interesting paper:
http://www.cl.cam.ac.uk/~mb566/papers/tacc-hs09.pdf
It's fascinating stuff, and I *think* I understand the gist of what it's
saying. However, the paper is utterly festooned with formulas that look
so absurdly over-the-top that they might almost be
Andrew Coppin andrewcop...@btinternet.com writes:
Does anybody have any idea which particular dialect of pure math this
paper is speaking? (And where I can go read about it...)
It's pretty garden-variety programming language/type theory. I can
recommend Benjamin Pierce's Types and Programming
I think you would enjoy reading (and working) through TAPL[1] and/or
Software Foundations[2] if this interests you.
Cheers,
Thomas
[1]
http://www.amazon.com/Types-Programming-Languages-Benjamin-Pierce/dp/0262162091
[2] http://www.cis.upenn.edu/~bcpierce/sf/
On Fri, Oct 15, 2010 at 1:36 PM,
On Oct 15, 2010, at 1:36 PM, Andrew Coppin wrote:
Does anybody have any idea which particular dialect of pure math
this paper is speaking? (And where I can go read about it...)
It's some kind of typed logic with lambda abstraction and some notion
of witnessing, using Gertzen (I think!)
On Thu, Oct 14, 2010 at 1:41 PM, Peter Marks pe...@indigomail.net wrote:
If you start Yi with no config file, press any key, press h, choose a key
binding, then save the file, you get a file c:\Users\peter\.yi\yi.hs
Oh, indeed. I didn't realize that. The behavior is defined in
Hey everyone,
Out of curiosity, are there any plans for GHC to eventually use the
Strict Core language described in
http://www.cl.cam.ac.uk/~mb566/papers/tacc-hs09.pdf?
Cheers,
Greg
___
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
On Fri, Oct 15, 2010 at 09:28:09PM +0100, Andrew Coppin wrote:
http://k1024.org/~iusty/papers/icfp10-haskell-reagent.pdf
I'm sure some of you have seen this already. For those who lack the
time or inclination to read through the (six) pages of this report,
here's the summary...
Nice
On 15/10/2010 10:27 PM, Gregory Crosswhite wrote:
Hey everyone,
Out of curiosity, are there any plans for GHC to eventually use the
Strict Core language described in
http://www.cl.cam.ac.uk/~mb566/papers/tacc-hs09.pdf?
Is that because I just mentioned the paper?
Regardless, I'd be quite
On 15/10/2010 10:43 PM, Iustin Pop wrote:
On Fri, Oct 15, 2010 at 09:28:09PM +0100, Andrew Coppin wrote:
http://k1024.org/~iusty/papers/icfp10-haskell-reagent.pdf
I'm sure some of you have seen this already. For those who lack the
time or inclination to read through the (six) pages of this
Yes, I had seen this paper before and wondered the same thing at the
time, but it was only just now when you brought the paper up that I
realized I could ask people about it here. :-)
On 10/15/2010 03:01 PM, Andrew Coppin wrote:
On 15/10/2010 10:27 PM, Gregory Crosswhite wrote:
Hey
Somebody showed me this the other day, and I thought it was interesting:
http://www.cs.umass.edu/~emery/pubs/f034-hertz.pdf
Basically, we designed a garbage collector which tries to avoid
touching memory pages that have been swapped out to disk just because we
need to do a GC sweep. Which is
On Fri, Oct 15, 2010 at 11:08:14PM +0100, Andrew Coppin wrote:
On 15/10/2010 10:43 PM, Iustin Pop wrote:
On Fri, Oct 15, 2010 at 09:28:09PM +0100, Andrew Coppin wrote:
I'm surprised about the profiler. They seem really, really impressed
with it. Which is interesting to me, since I can never
On 15/10/2010 11:10 PM, Gregory Crosswhite wrote:
Yes, I had seen this paper before and wondered the same thing at the
time, but it was only just now when you brought the paper up that I
realized I could ask people about it here. :-)
I wonder if anybody has a list somewhere of really cool
On 15/10/2010 11:18 PM, Iustin Pop wrote:
I know about zipWith. And if the profile tells me I spend too much time
in zipWith, it means a few things:
- zipWith might have to force evaluation of the results, hence the
incorrect attribution of costs
- if even after that zipWith is the culprit,
-- Given a definition of view which is essentially a synonym for show:
class View a where
view :: a - String
instance View Int where
view = show
-- why does show 2 compile, while view 2 gives an
-- 'Ambiguous type variable' error
fine = view (2::Int)
noProblem
On 16 October 2010 00:47, Jacek Generowicz jacek.generow...@cern.ch wrote:
-- why does show 2 compile, while view 2 gives an
-- 'Ambiguous type variable' error
fine = view (2::Int)
noProblem = show 2
ambiguousTypeVariable = view 2
Don't integral literals default
On 16 October 2010 09:47, Jacek Generowicz jacek.generow...@cern.ch wrote:
-- Given a definition of view which is essentially a synonym for show:
class View a where
view :: a - String
instance View Int where
view = show
-- why does show 2 compile, while view 2 gives an
--
On 10/15/2010 03:15 PM, Andrew Coppin wrote:
On the other hand, their implementation uses a modified Linux kernel,
and no sane person is going to recompile their OS kernel with a custom
patch just to run Haskell applications, so we can't do quite as well
as they did. But still, and
On 2010 Oct 16, at 00:51, Ivan Lazar Miljenovic wrote:
On 16 October 2010 09:47, Jacek Generowicz
jacek.generow...@cern.ch wrote:
-- Given a definition of view which is essentially a synonym for
show:
class View a where
view :: a - String
instance View Int where
view = show
-- why
Correct, here's a video of Simon explaining the thunk blackholing
issue and its solution in GHC 7:
http://vimeo.com/15573590
On 15 October 2010 21:31, Gregory Collins g...@gregorycollins.net wrote:
Evan Laforge qdun...@gmail.com writes:
The only workaround I could find is to immediately read
On 2010 Oct 16, at 01:14, Jacek Generowicz wrote:
On 2010 Oct 16, at 00:51, Ivan Lazar Miljenovic wrote:
2 is a generic number. If you don't specify a type, it usually
defaults to Integer. All Num instances that come in the Prelude have
Show instances, so no matter which gets picked show 2
On Saturday 16 October 2010 01:14:51, Jacek Generowicz wrote:
On 2010 Oct 16, at 00:51, Ivan Lazar Miljenovic wrote:
On 16 October 2010 09:47, Jacek Generowicz
jacek.generow...@cern.ch wrote:
-- Given a definition of view which is essentially a synonym for
show:
class View a where
On Fri, Oct 15, 2010 at 4:21 PM, Andrew Coppin
andrewcop...@btinternet.com wrote:
On 15/10/2010 11:10 PM, Gregory Crosswhite wrote:
Yes, I had seen this paper before and wondered the same thing at the
time, but it was only just now when you brought the paper up that I realized
I could ask
jacek.generow...@cern.ch wrote:
-- Given a definition of view which is essentially a synonym for
show:
class View a where
view :: a - String
instance View Int where
view = show
-- why does show 2 compile, while view 2 gives an
-- 'Ambiguous type variable' error
fine =
On Saturday 16 October 2010 01:18:55, Jacek Generowicz wrote:
On 2010 Oct 16, at 01:14, Jacek Generowicz wrote:
On 2010 Oct 16, at 00:51, Ivan Lazar Miljenovic wrote:
2 is a generic number. If you don't specify a type, it usually
defaults to Integer. All Num instances that come in the
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On 10/15/10 11:26 , Don Stewart wrote:
Linux users don't have easy binary installers, usually. What can we do
about this bootstrapping problem?
I thought the answer to that was supposed to be bug your distribution to
package the Platform.
- --
On 2010 Oct 16, at 01:39, Daniel Fischer wrote:
On Saturday 16 October 2010 01:18:55, Jacek Generowicz wrote:
On 2010 Oct 16, at 01:14, Jacek Generowicz wrote:
On 2010 Oct 16, at 00:51, Ivan Lazar Miljenovic wrote:
2 is a generic number. If you don't specify a type, it usually
defaults to
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On 10/15/10 16:28 , Andrew Coppin wrote:
I'm surprised about the profiler. They seem really, really impressed with
it. Which is interesting to me, since I can never seen to get anything
sensible out of it. It always seems to claim that my program
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On 10/15/10 16:36 , Andrew Coppin wrote:
Does anybody have any idea which particular dialect of pure math this paper
is speaking? (And where I can go read about it...)
Type theory. It makes my head spin, too, since essentially my only exposure
to
This is a critique of the current 'Haskell Blurb', the first paragraph on
www.haskell.org.
This blurb should, IMO, give a concise description of what Haskell, the
programming language, is, what makes it different from other languages, and
why I should be interested in it.
What it does, instead,
Great! It's a Friday. Why not step in.
Just some context, since the current blurb was born from a critique at
CUFP 2007, prior to which the Haskell blurb was:
Haskell is a general purpose, purely functional programming
language. Haskell compilers are freely available for almost any
Quoth Ben Franksen ben.frank...@online.de,
Enough. I think I have made my point.
Yes, though possibly a little overstated it. While it's easy to share
your distaste for the blurb, if you take a generous attitude towards it,
most of it is true enough.
The implementation specific features are
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