Re: [Haskell-cafe] How to use unsafePerformIO properly (safely?)
In Feldspar's module for observable sharing [1] I use the following
{-# OPTIONS_GHC -O0 #-}
which I assumed would take care of the steps required for
unsafePerformIO. Could someone please tell if this assumption is correct?
(Of course, observable sharing is not safe regardless, but that's beside
the point :) )
/ Emil
[1]
http://hackage.haskell.org/packages/archive/feldspar-language/0.2/doc/html/src/Feldspar-Core-Ref.html
Ivan Miljenovic skrev:
I use the dreaded unsafePerformIO for a few functions in my graphviz
library (
http://hackage.haskell.org/packages/archive/graphviz/2999.8.0.0/doc/html/src/Data-GraphViz.html
). However, a few months ago someone informed me that the
documentation for unsafePerformIO had some steps that should be
followed whenever it's used:
http://www.haskell.org/ghc/docs/latest/html/libraries/base-4.2.0.0/System-IO-Unsafe.html
.
Looking through this documentation, I'm unsure on how to deal with the
last two bullet points (adding NOINLINE pragmas is easy). The code
doesn't combine IO actions, etc. and I don't deal with mutable
variables, so do I have to worry about them?
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[Haskell-cafe] Data Structures GSoC
Hello. I am hoping to take on the Data Structures project proposed two years ago by Don Stewart herehttp://hackage.haskell.org/trac/summer-of-code/ticket/1549, this summer. Before I write up my proposal to Google, I wanted to gauge the reaction of the Haskell community to this project. Particularly: -What Data Structures in the current libraries are in most dire need of improvement? -How necessary do you think a Containers Library revision is? -Should I attempt to build on the work Jamie Brandon did with Map as generalised tries, or is that beyond the scope of this project I am very excited to work with functional data structures, and I would greatly appreciate any input. -Nathan Hunter ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Data Structures GSoC
Nathan Hunter enfer...@gmail.com wrote: -What Data Structures in the current libraries are in most dire need of improvement? -How necessary do you think a Containers Library revision is? -Should I attempt to build on the work Jamie Brandon did with Map as generalised tries, or is that beyond the scope of this project As I see it, the most dire need is a unified interface to everything, as well as instance selection, think type instance MapOf Int = IntMap type instance MapOf (a,b,c) =Tuple3Map(MapOf a)(MapOf b)(MapOf c) a b c (gmap is very, very handy in every other aspect) We have a lot of useful interfaces (e.g. ListLike, Edison), but they don't seem to enjoy wide-spread popularity. There's some lack when it comes to hashtables (I'd like to see a Haskell implementation of perfect hashing, as that's sometimes jolly useful) as well as cache-obliviousness (which is a can of worms: Ensuring data layout requires using mutable Arrays, which sucks, so what we actually need is a gc/allocator that can be told to allocate in van Emde Boas layout), but in general, the implementation side is fine. I would also like to be able to match on the left head of Data.Sequence in the same way I can match on Lists (see e.g. [1]), but I guess there'd have to me more commutity backing for that to become reality. [1] http://hackage.haskell.org/trac/ghc/ticket/3583 -- (c) this sig last receiving data processing entity. Inspect headers for copyright history. All rights reserved. Copying, hiring, renting, performance and/or quoting of this signature prohibited. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] benchmarking pure code
Hello, I'm writing a library for dealing with binders and I want to benchmark it against DeBruijn, Locally Nameless, HOAS, etc. One on my benchmark consists in 1. generating a big term \x.t 2. substituting u fox in t The part I want to benchmark is 2. In particular I would like that: a. \x.t is already evaluated when I run 2 (I don't want to measure the performances of the generator) b. the action of substituting u for x in t were measured as if I had to fully evaluate the result (by printing the resulting term for instance). After looking at what was available on hackage, i set my mind on strictbench, which basically calls (rnf x `seq` print ) and then uses benchpress to measure the pure computation x. Since I wanted (a), my strategy was (schematically): let t = genterm rnf t `seq` print bench (subst u t) I got numbers I didn't expect so I ran the following program: let t = genterm print t bench (subst u t) and then I got other numbers! Which were closer to what I think they should be, so I may be happy with them, but all of this seems to indicate that rnf doesn't behave as intended. Then I did something different: I wrote two programs. One that prints the result of (subst u t): let t = genterm let x = (subst u t) print x bench (print x) recorded the numbers of that one and then ran the program: let t = genterm bench (print (subst u t)) got the numbers, and substracted the first ones to them. By doing so, I'm sure that I get realistic numbers at least: since I print the whole resulting term, I've got a visual proof that it's been evaluated. But this is not very satisfactory. Does anyone have an idea why calling rnf before the bench doesn't seem to cache the result as calling show does? (my instances of NFData follow the scheme described in strictbench documentation). If not, do you think that measuring (computation + pretty printing time - pretty printing time) is ok? Regards, Paul ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] benchmarking pure code
Excerpts from Paul Brauner's message of Wed Mar 31 03:17:02 -0400 2010: The part I want to benchmark is 2. In particular I would like that: a. \x.t is already evaluated when I run 2 (I don't want to measure the performances of the generator) b. the action of substituting u for x in t were measured as if I had to fully evaluate the result (by printing the resulting term for instance). Criterion uses Control.DeepSeq; perhaps this is what you are looking for? Cheers, Edward ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] benchmarking pure code
On Wed, Mar 31, 2010 at 9:17 AM, Paul Brauner paul.brau...@loria.fr wrote: Does anyone have an idea why calling rnf before the bench doesn't seem to cache the result as calling show does? (my instances of NFData follow the scheme described in strictbench documentation). Is it possible you could show us your term type and your NFData instance? regards, Bas ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Data Structures GSoC
On 31/03/2010, at 18:14, Achim Schneider wrote: We have a lot of useful interfaces (e.g. ListLike, Edison), but they don't seem to enjoy wide-spread popularity. Perhaps that's an indication that we need different interfaces? IMO, huge classes which generalise every useful function we can think of just isn't the right approach. We need small interfaces between containers and algorithms. In fact, the situation is perhaps somewhat similar to C++ where by providing exactly that the STL has been able to replace OO-style collection libraries which never really worked all that well. Roman ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Data Structures GSoC
Nathan, For what it is worth: I'd propose that Data.HashTable needs to be replaced; it appears to me having played around with it and found it wanting that its limitations are pretty common knowledge in the Haskell community. (I'm sure most people on this list would already know much more about the limitations of the existing HashTable library than do I, for am only new to Haskell, so sorry if my suggestion is an eyeball-roller). Darryn. On Wed, 2010-03-31 at 00:00 -0700, Nathan Hunter wrote: Hello. I am hoping to take on the Data Structures project proposed two years ago by Don Stewart here, this summer. Before I write up my proposal to Google, I wanted to gauge the reaction of the Haskell community to this project. Particularly: -What Data Structures in the current libraries are in most dire need of improvement? -How necessary do you think a Containers Library revision is? -Should I attempt to build on the work Jamie Brandon did with Map as generalised tries, or is that beyond the scope of this project I am very excited to work with functional data structures, and I would greatly appreciate any input. -Nathan Hunter ___ 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] why doesn't time allow diff of localtimes ?
Hi, Quoting bri...@aracnet.com: which is a variation of the question, why can't I compare localtimes ? or am I missing something in Time (yet again). Am Mittwoch, den 31.03.2010, 01:32 -0400 schrieb wagne...@seas.upenn.edu: Two values of LocalTime may well be computed with respect to different timezones, which makes the operation you ask for dangerous. First convert to UTCTime (with localTimeToUTC), then compare. but this leads to the question: Why can I not compare or diff ZonedTime? Greetings, Joachim -- Joachim nomeata Breitner mail: m...@joachim-breitner.de | ICQ# 74513189 | GPG-Key: 4743206C JID: nome...@joachim-breitner.de | http://www.joachim-breitner.de/ Debian Developer: nome...@debian.org 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] More Language.C work for Google's Summer of Code
Malcolm would have to attest to how complete it is w.r.t. say, gcc's preprocessor, cpphs is intended to be as faithful to the CPP standard as possible, whilst still retaining the extra flexibility we want in a non-C environment, e.g. retaining the operator symbols //, /*, and */. If the behaviour of cpphs does not match gcc -E, then it is either a bug (please report it) or an intentional feature. Real CPP is rather horribly defined as a lexical analyser for C, so has a builtin notion of identifier, operator, etc, which is not so useful for all the other settings in which we just want to use conditional inclusion or macros. Also, CPP fully intermingles conditionals, file inclusion, and macro expansion, whereas cpphs makes a strenuous effort to separate those things into logical phases: first the conditionals and inclusions, then macro expansion. This separation makes it possible to run only one or other of the phases, which can occasionally be useful. One concern is that Language.C is BSD-licensed (and it would be nice to keep it that way), and cpphs is LGPL. However, if cpphs remained a separate program, producing C + extra stuff as output, and the Language.C parser understood the extra stuff, this could accomplish what I'm interested in. As for licensing, yes, cpphs as a standalone binary, is GPL. The library version is LGPL. One misconception is that a BSD-licensed library cannot use an LGPL'd library - of course it can. You just need to ensure that everyone can update the LGPL'd part if they wish. And as I always state for all of my tools, if the licence is a problem for any user, contact me to negotiate terms. I'm perfectly willing to allow commercial distribution with exemption from some of the GPL obligations. (And I note in passing that other alternatives like gcc are also GPL'd.) Regards, Malcolm ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] benchmarking pure code
Hello, actually I don't know if I can. I totally wouldn't mind but this is mainly my co-author work and I don't know if he would (I suppose not but since he is sleeping right now I can't check). However let's assume it's a deBruijn representation for instance, I can tell you the scheme I used: data Term = Lam Term | App Term Term | Var Int instance NFData where rnf (Lam t) = rnf t rnf (App t1 t2) = rnf t1 `seq` rnf t2 rnf (Var x) = rnf x the actual datatype doesn't have fancy stuff like higher-order types for constructors, it's really similar. The only difference is that it is a GADT, but this souldn't change anything right? Did I make some mistake in instancing NFData ? Regards, Paul On Wed, Mar 31, 2010 at 09:32:29AM +0200, Bas van Dijk wrote: On Wed, Mar 31, 2010 at 9:17 AM, Paul Brauner paul.brau...@loria.fr wrote: Does anyone have an idea why calling rnf before the bench doesn't seem to cache the result as calling show does? (my instances of NFData follow the scheme described in strictbench documentation). Is it possible you could show us your term type and your NFData instance? regards, Bas ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: ANN: data-category, restricted categories
On Tuesday 30 March 2010 4:34:10 pm Ashley Yakeley wrote: Worse than that, if bottom is a value, then Hask is not a category! Note that while undefined is bottom, (id . undefined) and (undefined . id) are not. Hask can be a category even if bottom is a value, with slight modification. That specific problem can be overcome by eliminating seq (and associated stuff; strict fields, bang patterns, ...), because it is the only thing in the language that can distinguish between the extensionally equal: undefined \_ - undefined the latter being what you get from id . undefined and undefined . id. Bottom, or more specifically, lifted types, tend to ruin other nice categorical constructions, though. Lifted sums are not Hask coproducts, lifted products are not Hask products, the empty type is terminal, rather than initial, and () isn't terminal. But, if we ignore bottoms, these deficiencies disappear. See, of course, Fast and Loose Reasoning is Morally Correct. * -- Dan [*] http://www.comlab.ox.ac.uk/jeremy.gibbons/publications/fast+loose.pdf ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Numeric.LinearProgramming - confusion in constructors for bounds
Hi everyone and Alberto, Numeric.LinearProgramming[1] provides a very nice interface for solving LP optimisation problems, and the well-known simplex algorithm itself. I must say I quite liked the interface it provides, simple yet sufficient. But, to my understanding, there is a confusion in the constructor name (symbols actually) for constraints. In LP, one needs to write constraints in the form of ==, =, or = only. You *cannot *write a constraint using strict inequalities. The algorithm has nothing wrong, but I guess it would be better to have constructor symbols right. See [2] If this is a design choice, I think it should explicitly be stated. Regards, [1] http://hackage.haskell.org/package/hmatrix-glpk [2] http://hackage.haskell.org/packages/archive/hmatrix-glpk/0.1.0/doc/html/Numeric-LinearProgramming.html#t%3ABound -- Ozgur Akgun ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] GSoC and Machine learning
Note that, if any student is interested, the Haskell Neural Network library [1] is being rewritten from scratch. We (Thomas Bereknyi and I) are discussing many core data structure alternatives, with some suggestions from Edward Kmett. There may even be some room for a rewrite or update of fgl, possibly with an alternative conception, to fit well HNN. I am definitely not sure if this is worth a GSoC and if the community would benefit that much from such a work, but it's there. [1] http://haskell.org/haskellwiki/HNN On Tue, Mar 30, 2010 at 1:55 PM, Grzegorz C pite...@gmail.com wrote: Hi, Ketil Malde-5 wrote: Once upon a time, I proposed a GSoC project for a machine learning library. I still get some email from prospective students about this, whom I discourage as best I can by saying I don't have the time or interest to pursue it, and that chances aren't so great since you guys tend to prefer language-related stuff instead of application-related stuff. But if anybody disagrees with my sentiments and is willing to mentor this, there are some smart students looking for an opportunity. I'd be happy to forward any requests. I don't know whether this is a good idea for a GSoC project, but I would certainly welcome such a library. I am using Haskell a bit for statistical NLP: in my experience currently Haskell is excellent for the components which deal with data preprocessing and feature extraction, but when it comes to implementing the core training algorithms and running them on large data sets, it's easy to get very poor performance and/or unexpected stack overflows. So if a library could provide some well-tuned and tested building blocks for implementing the performance critical parts of machine learning algorithms, it would improve the coding experience in a major way. Best, -- Grzegorz -- View this message in context: http://old.nabble.com/my-gsoc-project-topic-tp28068970p28081419.html Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- Alp Mestanogullari http://alpmestan.wordpress.com/ http://alp.developpez.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Implementation of Functional Languages - a tutorial
Hi Everybody, I've started reading SPJ's book - When I tried to execute some sample code in miranda, I found that Miranda does not seem to recognize things like import Utils or module Langauge where ... Has someone created a clean compilable miranda source out of this book? -- Regards, Kashyap ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] GSoC and Machine learning
On Wed, Mar 31, 2010 at 1:19 PM, Alp Mestanogullari a...@mestan.fr wrote: Note that, if any student is interested, the Haskell Neural Network library [1] is being rewritten from scratch. We (Thomas Bereknyi and I) are discussing many core data structure alternatives, with some suggestions from Edward Kmett. There may even be some room for a rewrite or update of fgl, possibly with an alternative conception, to fit well HNN. I am definitely not sure if this is worth a GSoC and if the community would benefit that much from such a work, but it's there. [1] http://haskell.org/haskellwiki/HNN Well, I'd like to tie two of my favourite things together. I'm using neural nets here and there (not for very big tasks though, yet) and I intended to use them in haskell too. The code from [0] was intended to become one day useful for a project on neural nets in Haskell. I would be interested in this project if it will be accepted and there would be mentors. [0]: http://pgraycode.wordpress.com/2010/01/25/a-general-network-module/ -- Mihai Maruseac ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Seeking advice about monadic traversal functions
Darryn Reid wrote:
I've coded a (fairly) general rewriting traversal - I suspect the
approach might be generalisable to all tree-like types, but this doesn't
concern me much right now. My purpose is for building theorem provers
for a number of logics, separating the overall control mechanism from
the specific rules for each logic.
The beauty of Haskell here is in being able to abstract the traversal
away from the specific reduction rules and languages of the different
logics. I have paired down the code here to numbers rather than modal
formulas for the sake of clarity and simplicity. My question is
two-fold:
1. Does my representation of the traversal seem good or would it be
better expressed differently? If so, I'd appreciate the thoughts of more
experienced Haskell users.
Looks fine to me, though I have no experience with tree
rewriting. :) I'd probably write it like this:
data Tableau a = Nil -- End of a path
| Single a (Tableau a) -- Conjunction
| Fork (Tableau a) (Tableau a) -- Disjunction
deriving (Eq, Show)
data Action = Cut | Next
type Rewriter m a = Tableau a - m (Tableau a, Action)
rewrite :: (Monad m) = Rewriter m a - Tableau a - m (Tableau a)
rewrite f t = f t = (uncurry . flip) go
where
go Cut t = return t
go Next Nil = return Nil
go Next (Single x t1) = liftM (Single x) (rewrite f t1)
go Next (Fork t1 t2 ) = liftM2 Fork (rewrite f t1)
(rewrite f t2)
In particular, liftM and liftM2 make it apparent that we're just
wrapping the result in a constructor.
In case you want more flexibility in moving from children to parents,
you may want to have a look at zippers
http://en.wikibooks.org/wiki/Haskell/Zippers
2. I cannot really see how to easily extend this to a queue-based
breadth-first traversal, which would give me fairness. I'm sure others
must have a good idea of how to do what I'm doing here except in
breadth-first order; I'd appreciate it very much if someone could show
me how to make a second breadth-first version.
This is more tricky than I thought! Just listing the nodes in
breadth-first order is straightforward, but the problem is that you
also want to build the result tree. Depth-first search follows the tree
structure more closely, so building the result was no problem.
The solution is to solve the easy problem of listing all nodes
in breadth-first order first, because it turns out that it's possible to
reconstruct the result tree from such a list! In other words, it's
possible to run breadth-first search in reverse, building the tree from
a list of nodes.
How exactly does this work? If you think about it, the analogous problem
for depth-first search is not too difficult, you just walk through the
list of nodes and build a stack; pushing Nil nodes and combining the
top two items when encountering Fork nodes. So, for solving the
breadth-first version, the idea is to build a queue instead of a stack.
The details of that are a bit tricky of course, you have to be careful
when to push what on the queue. But why bother being careful if we have
Haskell? I thus present the haphazardly named:
Lambda Fu, form 132 - linear serpent inverse
The idea is to formulate breadth-first search in a way that is *trivial*
to invert, and the key ingredient to that is a *linear* function, i.e.
one that never discards or duplicates data, but only shuffles it around.
Here is what I have in mind:
{-# LANGUAGE ViewPatterns #-}
import Data.Sequence as Seq -- this will be our queue type
import Data.List as List
type Node a = Tableau a -- just a node without children (ugly type)
type State a = ([Action],[(Action,Node a)], Seq (Tableau a))
queue (_,_,q) = q
nodes (_,l,_) = l
analyze :: State a - State a
analyze (Cut :xs, ts, viewl - t : q) =
(xs, (Cut , t ) : ts, q )
analyze (Next:xs, ts, viewl - Nil : q) =
(xs, (Next, Nil ) : ts, q )
analyze (Next:xs, ts, viewl - Single x t1 : q) =
(xs, (Next, Single x u) : ts, q | t1 )
analyze (Next:xs, ts, viewl - Fork t1 t2 : q) =
(xs, (Next, Fork u u ) : ts, (q | t1) | t2 )
u = Nil -- or undefined
bfs xs t = nodes $
until (Seq.null . queue) analyze (xs,[],singleton t)
So, bfs just applies analyze repeatedly on a suitable state which
includes the queue, the list of nodes in breadth-first order and a
stream of actions. (This is a simplified example, you will calculate the
actions on the fly of course.) To be able to pattern match on the queue,
I have used GHC's ViewPattern extension.
It should be clear that analyze performs exactly one step of a
breadth-first traversal.
Now, the key point is that analyze is *linear*, it never discards or
duplicates any of the input variables, it just
Re: [Haskell-cafe] Implementation of Functional Languages - a tutorial
2010/3/31 C K Kashyap ckkash...@gmail.com: Hi Everybody, I've started reading SPJ's book - When I tried to execute some sample code in miranda, I found that Miranda does not seem to recognize things like import Utils or module Langauge where ... Has someone created a clean compilable miranda source out of this book? Hi, If I remember correctly, the version of the book on the net contains Haskell code, even if the text is about Miranda. The example you give above is definitely Haskell. Cheers, Thu ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Implementation of Functional Languages - a tutorial
Great ... thanks Thu ... Regards, Kashyap On Wed, Mar 31, 2010 at 4:15 PM, minh thu not...@gmail.com wrote: 2010/3/31 C K Kashyap ckkash...@gmail.com: Hi Everybody, I've started reading SPJ's book - When I tried to execute some sample code in miranda, I found that Miranda does not seem to recognize things like import Utils or module Langauge where ... Has someone created a clean compilable miranda source out of this book? Hi, If I remember correctly, the version of the book on the net contains Haskell code, even if the text is about Miranda. The example you give above is definitely Haskell. Cheers, Thu -- Regards, Kashyap ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] benchmarking pure code
On Wed, Mar 31, 2010 at 11:06 AM, Paul Brauner paul.brau...@loria.fr wrote:
data Term = Lam Term | App Term Term | Var Int
instance NFData where
rnf (Lam t) = rnf t
rnf (App t1 t2) = rnf t1 `seq` rnf t2
rnf (Var x) = rnf x
the actual datatype doesn't have fancy stuff like higher-order
types for constructors, it's really similar. The only difference
is that it is a GADT, but this souldn't change anything right?
Did I make some mistake in instancing NFData ?
No, your NFData instance is correct. You first pattern match on the
term followed by recursively calling rnf on the sub-terms. This will
correctly force the entire term.
Maybe you could try using criterion[1] for your benchmark and see if
that makes any difference. Something like:
{-# LANGUAGE BangPatterns #-}
import Criterion.Main
main :: IO ()
main = let !t = genterm in defaultMain [bench subst $ nf (subst u) t]
regards,
Bas
[1] http://hackage.haskell.org/package/criterion
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Re: [Haskell-cafe] GSoC and Machine learning
Well, you can join #hnn or #haskell-soc to discuss that with us. But don't put too much hope on that, I'm quite sure it isn't GSoC worthy. OTOH, any contribution is always welcome heh. On Wed, Mar 31, 2010 at 12:39 PM, Mihai Maruseac mihai.marus...@gmail.comwrote: On Wed, Mar 31, 2010 at 1:19 PM, Alp Mestanogullari a...@mestan.fr wrote: Note that, if any student is interested, the Haskell Neural Network library [1] is being rewritten from scratch. We (Thomas Bereknyi and I) are discussing many core data structure alternatives, with some suggestions from Edward Kmett. There may even be some room for a rewrite or update of fgl, possibly with an alternative conception, to fit well HNN. I am definitely not sure if this is worth a GSoC and if the community would benefit that much from such a work, but it's there. [1] http://haskell.org/haskellwiki/HNN Well, I'd like to tie two of my favourite things together. I'm using neural nets here and there (not for very big tasks though, yet) and I intended to use them in haskell too. The code from [0] was intended to become one day useful for a project on neural nets in Haskell. I would be interested in this project if it will be accepted and there would be mentors. [0]: http://pgraycode.wordpress.com/2010/01/25/a-general-network-module/ -- Mihai Maruseac -- Alp Mestanogullari http://alpmestan.wordpress.com/ http://alp.developpez.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Haskell.org re-design
On Mon, Mar 29, 2010 at 3:44 AM, Christopher Done chrisd...@googlemail.com wrote: This is a post about re-designing the whole Haskell web site. I really like the design a lot. Here are some ideas: - There are several news streams going on at once. Perhaps Headlines and Events could be merged into one stream. After watching the Hackage RSS feed every day I don't know if it's interesting enough to put on a front page. Perhaps in a side bar which brings me to my next suggestions. - Multi column pages are tricky to scan! It works well in news papers since the page height is limited but for web pages I really prefer one main column. Perhaps the second column code be made more narrow? Perhaps the footer content could be promoted into this second column and have it be a more conventional right (or left) hand nav? - The quick links seem a bit random where they now appear. :) I'd also recommend looking at other programming languages web sites if you haven't done so already: http://www.ruby-lang.org/en/ http://www.python.org/ http://www.scala-lang.org/ Thanks for all your hard work! Cheers, Johan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] benchmarking pure code
On Wed, Mar 31, 2010 at 12:57 PM, Bas van Dijk v.dijk@gmail.com wrote: main = let !t = genterm in defaultMain [bench subst $ nf (subst u) t] Oops, that should be: main = let t = genterm in rnf t `seq` defaultMain [bench subst $ nf (subst u) t] Bas ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Implementation of Functional Languages - a tutorial
Looks like some functions are left as an exercise... I'd appreciate it if someone could share a complete code for the Core language On Wed, Mar 31, 2010 at 4:20 PM, C K Kashyap ckkash...@gmail.com wrote: Great ... thanks Thu ... Regards, Kashyap On Wed, Mar 31, 2010 at 4:15 PM, minh thu not...@gmail.com wrote: 2010/3/31 C K Kashyap ckkash...@gmail.com: Hi Everybody, I've started reading SPJ's book - When I tried to execute some sample code in miranda, I found that Miranda does not seem to recognize things like import Utils or module Langauge where ... Has someone created a clean compilable miranda source out of this book? Hi, If I remember correctly, the version of the book on the net contains Haskell code, even if the text is about Miranda. The example you give above is definitely Haskell. Cheers, Thu -- Regards, Kashyap -- Regards, Kashyap ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] benchmarking pure code
Thank you, I will look at that. But it seems that criterion uses NFData
no?
Paul
On Wed, Mar 31, 2010 at 12:57:20PM +0200, Bas van Dijk wrote:
On Wed, Mar 31, 2010 at 11:06 AM, Paul Brauner paul.brau...@loria.fr wrote:
data Term = Lam Term | App Term Term | Var Int
instance NFData where
rnf (Lam t) = rnf t
rnf (App t1 t2) = rnf t1 `seq` rnf t2
rnf (Var x) = rnf x
the actual datatype doesn't have fancy stuff like higher-order
types for constructors, it's really similar. The only difference
is that it is a GADT, but this souldn't change anything right?
Did I make some mistake in instancing NFData ?
No, your NFData instance is correct. You first pattern match on the
term followed by recursively calling rnf on the sub-terms. This will
correctly force the entire term.
Maybe you could try using criterion[1] for your benchmark and see if
that makes any difference. Something like:
{-# LANGUAGE BangPatterns #-}
import Criterion.Main
main :: IO ()
main = let !t = genterm in defaultMain [bench subst $ nf (subst u) t]
regards,
Bas
[1] http://hackage.haskell.org/package/criterion
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Re: [Haskell-cafe] Data.Graph?
Thanks, Ivan, for the note about the other alternatives and about possible additions to your library (and of course for the library itself!). I should mention that I completely missed containers in the hierarchical libraries (I was just looking in the base libraries). Sorry about that. Lee On Mar 30, 2010, at 7:23 PM, Ivan Miljenovic wrote: Sorry for the duplicate email Lee, but I somehow forgot to CC the mailing list :s On 31 March 2010 13:12, Lee Pike leep...@gmail.com wrote: I'd like it if there were a Data.Graph in the base libraries with basic graph-theoretic operations. Is this something that's been discussed? I'm kinda working on a replacement to Data.Graph that will provide graph-theoretic operations to a variety of graph types. For now, it appears that Graphalyze on Hackage is the most complete library for graph analysis; is that right? (I actually usually just want a pretty small subset of its functionality.) Yay, someone likes my code! :p I've been thinking about splitting off the algorithms section of Graphalyze for a while; maybe I should do so now... (though I was going to merge it into the above mentioned so-far-mainly-vapourware library...). There are a few other alternatives: * FGL has a variety of graph operations (but I ended up re-implementing a lot of the ones I wanted in Graphalyze because FGL returns lists of nodes and I wanted the resulting graphs for things like connected components, etc.). * The dom-lt library * GraphSCC * hgal (which is a really atrocious port of nauty that is extremely inefficient; I've started work on a replacement) * astar (which is generic for all graph types since you provide functions on the graph as arguments) With the exception of FGL, all of these are basically libraries that implement one particular algorithm/operation. -- 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] Data.Graph?
Lee Pike leep...@gmail.com writes: I should mention that I completely missed containers in the hierarchical libraries (I was just looking in the base libraries). Sorry about that. Oh, I thought you had done what most of us do: seen Data.Graph in containers and promptly dismissed it... _ (IIRC, it doesn't really have many graph operations defined there.) -- 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
[Haskell-cafe] Re: Data Structures GSoC
From: Roman Leshchinskiy r...@cse.unsw.edu.au On 31/03/2010, at 18:14, Achim Schneider wrote: We have a lot of useful interfaces (e.g. ListLike, Edison), but they don't seem to enjoy wide-spread popularity. Perhaps that's an indication that we need different interfaces? IMO, huge classes which generalise every useful function we can think of just isn't the right approach. We need small interfaces between containers and algorithms. In fact, the situation is perhaps somewhat similar to C++ where by providing exactly that the STL has been able to replace OO-style collection libraries which never really worked all that well. Agreed. There should be a hierarchy with multiple interfaces, e.g. Collection, List, Map, Set, etc. I can't speak for Edison, but ListLike only implements the List, and doesn't provide an appropriate base class. I also agree that the STL (as well as the generic collections in C#/ASP.Net) seem to take the best approach here. That being said, I also agree with Darryn Reid that Data.HashTable could use some work as a higher priority. John ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Data.Graph?
Oh, I thought you had done what most of us do: seen Data.Graph in containers and promptly dismissed it... _ (IIRC, it doesn't really have many graph operations defined there.) Yes, you're right---I just wanted to acknowledge that I'd missed that there was *something* there... Lee ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Are there any female Haskellers?
On Mon, Mar 29, 2010 at 4:48 PM, Steve Schafer st...@fenestra.com wrote: On Sun, 28 Mar 2010 20:38:49 -0700, you wrote: * The difference between genders is smaller than the difference between individuals If only people would understand and accept the near-universality of this: The difference between any group you want to discriminate against and any group you want to discriminate in favor of is smaller than the difference between individuals. Oh, come now, near-universality? There are millions of obvious counter-examples. (For example, the difference in running ability between people who are paralyzed from the neck down, and people who aren't, should be readily apparent.) I like the spirit of your idea, but let's be realistic here. -- mithrandi, i Ainil en-Balandor, a faer Ambar ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] ANN: Hakyll-2.0
Hello, On this spring day I would like to announce the 2.0 release of Hakyll[1], the static site generator. It is a rewrite, changes the API for the better and introduces some new features. A brief changelog: - Rewrite of the codebase to a clean, arrow based API. - Pagination was added. - Built-in functions to generate RSS and Atom. - Many bugfixes. - New tutorials added. Of course, all feedback is welcome. Kind regards, Jasper Van der Jeugt [1]: http://jaspervdj.be/hakyll ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] cabal through PHPProxy
Hello, i'm using PHPProxy to go on the internet (www.phpproxy.fr). How can i tell cabal to use this? Cheers, Corentin ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Numeric.LinearProgramming - confusion in constructors for bounds
Hi Ozgur, You are right, the operators are misleading. I will change them to :=: and :=:. And perhaps the symbol :: for the interval bound should also be improved... Thanks for your suggestion! Alberto Ozgur Akgun wrote: Hi everyone and Alberto, Numeric.LinearProgramming[1] provides a very nice interface for solving LP optimisation problems, and the well-known simplex algorithm itself. I must say I quite liked the interface it provides, simple yet sufficient. But, to my understanding, there is a confusion in the constructor name (symbols actually) for constraints. In LP, one needs to write constraints in the form of ==, =, or = only. You /cannot /write a constraint using strict inequalities. The algorithm has nothing wrong, but I guess it would be better to have constructor symbols right. See [2] If this is a design choice, I think it should explicitly be stated. Regards, [1] http://hackage.haskell.org/package/hmatrix-glpk [2] http://hackage.haskell.org/packages/archive/hmatrix-glpk/0.1.0/doc/html/Numeric-LinearProgramming.html#t%3ABound -- Ozgur Akgun ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Numeric.LinearProgramming - confusion in constructors for bounds
You are very welcome :) What about not an operator but a regular constructor for the interval thing? Something like: Between Double Double Nevertheless, I think :: is not bad at all. You can leave it as it is. Best, On 31 March 2010 14:57, Alberto Ruiz ar...@um.es wrote: Hi Ozgur, You are right, the operators are misleading. I will change them to :=: and :=:. And perhaps the symbol :: for the interval bound should also be improved... Thanks for your suggestion! Alberto Ozgur Akgun wrote: Hi everyone and Alberto, Numeric.LinearProgramming[1] provides a very nice interface for solving LP optimisation problems, and the well-known simplex algorithm itself. I must say I quite liked the interface it provides, simple yet sufficient. But, to my understanding, there is a confusion in the constructor name (symbols actually) for constraints. In LP, one needs to write constraints in the form of ==, =, or = only. You /cannot /write a constraint using strict inequalities. The algorithm has nothing wrong, but I guess it would be better to have constructor symbols right. See [2] If this is a design choice, I think it should explicitly be stated. Regards, [1] http://hackage.haskell.org/package/hmatrix-glpk [2] http://hackage.haskell.org/packages/archive/hmatrix-glpk/0.1.0/doc/html/Numeric-LinearProgramming.html#t%3ABound -- Ozgur Akgun -- Ozgur Akgun ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: GSOC Haskell Project
On 30/03/2010 20:57, Mihai Maruseac wrote: I'd like to introduce my idea for the Haskell GSOC of this year. In fact, you already know about it, since I've talked about it here on the haskell-cafe, on my blog and on reddit (even on #haskell one day). Basically, what I'm trying to do is a new debugger for Haskell, one that would be very intuitive for beginners, a graphical one. I've given some examples and more details on my blog [0], [1], also linked on reditt and other places. This is not the application, I'm posting this only to receive some kind of feedback before writing it. I know that it seems to be a little too ambitious but I do think that I can divide the work into sessions and finish what I'll start this summer during the next year and following. [0]: http://pgraycode.wordpress.com/2010/03/20/haskell-project-idea/ [1]: http://pgraycode.wordpress.com/2010/03/24/visual-haskell-debugger-part-2/ Thanks for your attention, My concerns would be: - it doesn't look like it would scale very well beyond small examples, the graphical representation would very quickly get unwieldy, unless you have some heavyweight UI stuff to make it navigable. - it's too ambitious - have you looked around to see what kind of debugging tools people are asking for? The most oft-requested feature is stack traces, and there's lots of scope for doing something there (but also many corpses littering the battlefield, so watch out!) Cheers, Simon ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
RE: [Haskell-cafe] cabal through PHPProxy
From: haskell-cafe-boun...@haskell.org [mailto:haskell-cafe-boun...@haskell.org] On Behalf Of Dupont Corentin i'm using PHPProxy to go on the internet (www.phpproxy.fr). How can i tell cabal to use this? I think the normal way is through setting HTTP_PROXY env var e.g. set HTTP_PROXY=http://localhost:3128 (I have a cntlm proxy on my local machine because our corporate proxy uses NTLM authentication, which cabal does not support.) Alistair * Confidentiality Note: The information contained in this message, and any attachments, may contain confidential and/or privileged material. It is intended solely for the person(s) or entity to which it is addressed. Any review, retransmission, dissemination, or taking of any action in reliance upon this information by persons or entities other than the intended recipient(s) is prohibited. If you received this in error, please contact the sender and delete the material from any computer. * ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Benchmarking and Garbage Collection
On 04/03/2010 22:01, Neil Brown wrote: Jesper Louis Andersen wrote: On Thu, Mar 4, 2010 at 8:35 PM, Neil Brown nc...@kent.ac.uk wrote: CML is indeed the library that has the most markedly different behaviour. In Haskell, the CML package manages to produce timings like this for fairly simple benchmarks: %GC time 96.3% (96.0% elapsed) I knew from reading the code that CML's implementation would do something like this, although I do wonder if it triggers some pathological case in the GC. That result is peculiar. What are you doing to the library, and what do you expect happens? Since I have some code invested on top of CML, I'd like to gain a little insight if possible. In trying to simplify my code, the added time has moved from GC time to EXIT time (and increased!). This shift isn't too surprising -- I believe the time is really spent trying to kill lots of threads. Here's my very simple benchmark; the main thread repeatedly chooses between receiving from two threads that are sending to it: import Control.Concurrent import Control.Concurrent.CML import Control.Monad main :: IO () main = do let numChoices = 2 cs - replicateM numChoices channel mapM_ forkIO [replicateM_ (10 `div` numChoices) $ sync $ transmit c () | c - cs] replicateM_ 10 $ sync $ choose [receive c (const True) | c - cs] Compiling with -threaded, and running with +RTS -s, I get: INIT time 0.00s ( 0.00s elapsed) MUT time 2.68s ( 3.56s elapsed) GC time 1.84s ( 1.90s elapsed) EXIT time 89.30s ( 90.71s elapsed) Total time 93.82s ( 96.15s elapsed) FYI, I've now fixed this in my working branch: INIT time0.00s ( 0.00s elapsed) MUT time0.88s ( 0.88s elapsed) GCtime0.85s ( 1.04s elapsed) EXIT time0.05s ( 0.07s elapsed) Total time1.78s ( 1.97s elapsed) Cheers, Simon ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] cabal through PHPProxy
Thanks for the response. I don't think this will work because PHPProxy is a web based proxy. To use it, you have to type the http address you want in a field on the page. Corentin On 3/31/10, Bayley, Alistair alistair.bay...@invesco.com wrote: From: haskell-cafe-boun...@haskell.org [mailto:haskell-cafe-boun...@haskell.org] On Behalf Of Dupont Corentin i'm using PHPProxy to go on the internet (www.phpproxy.fr). How can i tell cabal to use this? I think the normal way is through setting HTTP_PROXY env var e.g. set HTTP_PROXY=http://localhost:3128 (I have a cntlm proxy on my local machine because our corporate proxy uses NTLM authentication, which cabal does not support.) Alistair * Confidentiality Note: The information contained in this message, and any attachments, may contain confidential and/or privileged material. It is intended solely for the person(s) or entity to which it is addressed. Any review, retransmission, dissemination, or taking of any action in reliance upon this information by persons or entities other than the intended recipient(s) is prohibited. If you received this in error, please contact the sender and delete the material from any computer. * ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Shootout update
I'm wondering... Since the DPH libraries are shipped with GHC by default are we allowed to use them for the shootout? Roman On 30/03/2010, at 19:25, Simon Marlow wrote: The shootout (sorry, Computer Language Benchmarks Game) recently updated to GHC 6.12.1, and many of the results got worse. Isaac Gouy has added the +RTS -qg flag to partially fix it, but that turns off the parallel GC completely and we know that in most cases better results can be had by leaving it on. We really need to tune the flags for these benchmarks properly. http://shootout.alioth.debian.org/u64q/haskell.php It may be that we have to back off to +RTS -N3 in some cases to avoid the last-core problem (http://hackage.haskell.org/trac/ghc/ticket/3553), at least until 6.12.2. Any volunteers with a quad-core to take a look at these programs and optimise them for 6.12.1? Cheers, Simon ___ 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] Shootout update
On 31/03/2010 16:06, Roman Leshchinskiy wrote: I'm wondering... Since the DPH libraries are shipped with GHC by default are we allowed to use them for the shootout? I don't see why not. *evil grin* Simon Roman On 30/03/2010, at 19:25, Simon Marlow wrote: The shootout (sorry, Computer Language Benchmarks Game) recently updated to GHC 6.12.1, and many of the results got worse. Isaac Gouy has added the +RTS -qg flag to partially fix it, but that turns off the parallel GC completely and we know that in most cases better results can be had by leaving it on. We really need to tune the flags for these benchmarks properly. http://shootout.alioth.debian.org/u64q/haskell.php It may be that we have to back off to +RTS -N3 in some cases to avoid the last-core problem (http://hackage.haskell.org/trac/ghc/ticket/3553), at least until 6.12.2. Any volunteers with a quad-core to take a look at these programs and optimise them for 6.12.1? Cheers, Simon ___ 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: GSOC Haskell Project
On Wed, Mar 31, 2010 at 7:21 AM, Simon Marlow marlo...@gmail.com wrote: On 30/03/2010 20:57, Mihai Maruseac wrote: I'd like to introduce my idea for the Haskell GSOC of this year. In fact, you already know about it, since I've talked about it here on the haskell-cafe, on my blog and on reddit (even on #haskell one day). Basically, what I'm trying to do is a new debugger for Haskell, one that would be very intuitive for beginners, a graphical one. I've given some examples and more details on my blog [0], [1], also linked on reditt and other places. This is not the application, I'm posting this only to receive some kind of feedback before writing it. I know that it seems to be a little too ambitious but I do think that I can divide the work into sessions and finish what I'll start this summer during the next year and following. [0]: http://pgraycode.wordpress.com/2010/03/20/haskell-project-idea/ [1]: http://pgraycode.wordpress.com/2010/03/24/visual-haskell-debugger-part-2/ Thanks for your attention, My concerns would be: - it doesn't look like it would scale very well beyond small examples, the graphical representation would very quickly get unwieldy, unless you have some heavyweight UI stuff to make it navigable. - it's too ambitious - have you looked around to see what kind of debugging tools people are asking for? The most oft-requested feature is stack traces, and there's lots of scope for doing something there (but also many corpses littering the battlefield, so watch out!) I would be much more interested in seeing the foundations improved than I would be in having nice things built on them. In other words, I agree with Simon that stack traces would be many times more valuable to me than graphical representations. Once the foundations are robust, then we can build nice things on top of them. Perhaps the reason you're interested in graphical representations is because you want to help people 'visualize', or understand, the problem. Not all visualizations need to be graphical in the GUI sense. It's really about representing things in a way that helps humans reason about it. Getting the right information to people as they need it is probably the best place to start. Jason ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Implementation of Functional Languages - a tutorial
I was working through this book last year, and posted my work at https://patch-tag.com/r/wh5a/CoreCompiler/home. It was almost complete. On Wed, Mar 31, 2010 at 7:12 AM, C K Kashyap ckkash...@gmail.com wrote: Looks like some functions are left as an exercise... I'd appreciate it if someone could share a complete code for the Core language On Wed, Mar 31, 2010 at 4:20 PM, C K Kashyap ckkash...@gmail.com wrote: Great ... thanks Thu ... Regards, Kashyap On Wed, Mar 31, 2010 at 4:15 PM, minh thu not...@gmail.com wrote: 2010/3/31 C K Kashyap ckkash...@gmail.com: Hi Everybody, I've started reading SPJ's book - When I tried to execute some sample code in miranda, I found that Miranda does not seem to recognize things like import Utils or module Langauge where ... Has someone created a clean compilable miranda source out of this book? Hi, If I remember correctly, the version of the book on the net contains Haskell code, even if the text is about Miranda. The example you give above is definitely Haskell. Cheers, Thu -- Regards, Kashyap -- Regards, Kashyap ___ 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] Do I need to roll my own?
I'm looking at iteratee as a way to replace my erroneous and really inefficient lazy-IO-based backend for an expect like Monad DSL I've been working for about 6 months or so now on and off. The problem is I want something like: expect some String send some response to block or perhaps timeout, depending on the environment, looking for some String on an input Handle, and it appears that iteratee works in a very fixed block size. While a fixed block size is ok, if I can put back unused bytes into the enumerator somehow (I may need to put a LOT back in some cases, but in the common case I will not need to put any back as most expect-like scripts typically catch the last few bytes of data sent before the peer is blocked waiting for a response...) Otherwise, I'm going to want to roll my own iteratee style library where I have to say NotDone howMuchMoreIThinkINeed so I don't over consume the input stream. Does that even make any sense? I'm kind of brainstorming in this email unfortunately :-) Dave ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Shootout update
Certainly. rl: I'm wondering... Since the DPH libraries are shipped with GHC by default are we allowed to use them for the shootout? Roman On 30/03/2010, at 19:25, Simon Marlow wrote: The shootout (sorry, Computer Language Benchmarks Game) recently updated to GHC 6.12.1, and many of the results got worse. Isaac Gouy has added the +RTS -qg flag to partially fix it, but that turns off the parallel GC completely and we know that in most cases better results can be had by leaving it on. We really need to tune the flags for these benchmarks properly. http://shootout.alioth.debian.org/u64q/haskell.php It may be that we have to back off to +RTS -N3 in some cases to avoid the last-core problem (http://hackage.haskell.org/trac/ghc/ticket/3553), at least until 6.12.2. Any volunteers with a quad-core to take a look at these programs and optimise them for 6.12.1? Cheers, Simon ___ 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] Implementation of Functional Languages - a tutorial
Thanks Wei ... Having a working version would really help in going through the tutorial better. On Wed, Mar 31, 2010 at 9:32 PM, Wei Hu wei@gmail.com wrote: I was working through this book last year, and posted my work at https://patch-tag.com/r/wh5a/CoreCompiler/home. It was almost complete. On Wed, Mar 31, 2010 at 7:12 AM, C K Kashyap ckkash...@gmail.com wrote: Looks like some functions are left as an exercise... I'd appreciate it if someone could share a complete code for the Core language On Wed, Mar 31, 2010 at 4:20 PM, C K Kashyap ckkash...@gmail.com wrote: Great ... thanks Thu ... Regards, Kashyap On Wed, Mar 31, 2010 at 4:15 PM, minh thu not...@gmail.com wrote: 2010/3/31 C K Kashyap ckkash...@gmail.com: Hi Everybody, I've started reading SPJ's book - When I tried to execute some sample code in miranda, I found that Miranda does not seem to recognize things like import Utils or module Langauge where ... Has someone created a clean compilable miranda source out of this book? Hi, If I remember correctly, the version of the book on the net contains Haskell code, even if the text is about Miranda. The example you give above is definitely Haskell. Cheers, Thu -- Regards, Kashyap -- Regards, Kashyap ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- Regards, Kashyap ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Announce: Haskell Platform 2010.1.0.0 (beta) release
DekuDekuplex: Sorry for the late response, but just out of curiosity, are there any plans to provide a binary installer for either the Haskell Platform or GHC 6.12.1 for Mac OS X Leopard for the PowerPC CPU (as opposed to for the Intel x86 CPU)? I just checked the download-related Web sites for both the Haskell Platform for the Mac (see http://hackage.haskell.org/platform/mac.html) and for GHC 6.12.1 (see http://www.haskell.org/ghc/download_ghc_6_12_1.html), but could find no relevant information. Currently, I'm using GHC 6.8.2, but this is an outdated version. There is no one actively working on this, but should someone like to build such an installer, the HP site can gladly host it. -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] benchmarking pure code
On Wed, Mar 31, 2010 at 4:12 AM, Paul Brauner paul.brau...@loria.fr wrote: Thank you, I will look at that. But it seems that criterion uses NFData no? I do not know of anything wrong with NFData. What you're seeing is much more likely to be a bug in either the benchmarking library you're using, or in your use of it. Most of the benchmarking frameworks on Hackage are extremely dodgy, which was why I wrote criterion. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Data.Graph?
There are a number of us over on #hnn on freenode hacking away on the beginnings of a shiny new graph library based on some new tricks for annotated structures. Feel free to swing by the channel. -Edward Kmett On Tue, Mar 30, 2010 at 10:23 PM, Ivan Miljenovic ivan.miljeno...@gmail.com wrote: Sorry for the duplicate email Lee, but I somehow forgot to CC the mailing list :s On 31 March 2010 13:12, Lee Pike leep...@gmail.com wrote: I'd like it if there were a Data.Graph in the base libraries with basic graph-theoretic operations. Is this something that's been discussed? I'm kinda working on a replacement to Data.Graph that will provide graph-theoretic operations to a variety of graph types. For now, it appears that Graphalyze on Hackage is the most complete library for graph analysis; is that right? (I actually usually just want a pretty small subset of its functionality.) Yay, someone likes my code! :p I've been thinking about splitting off the algorithms section of Graphalyze for a while; maybe I should do so now... (though I was going to merge it into the above mentioned so-far-mainly-vapourware library...). There are a few other alternatives: * FGL has a variety of graph operations (but I ended up re-implementing a lot of the ones I wanted in Graphalyze because FGL returns lists of nodes and I wanted the resulting graphs for things like connected components, etc.). * The dom-lt library * GraphSCC * hgal (which is a really atrocious port of nauty that is extremely inefficient; I've started work on a replacement) * astar (which is generic for all graph types since you provide functions on the graph as arguments) With the exception of FGL, all of these are basically libraries that implement one particular algorithm/operation. -- 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 ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: iteratee: Do I need to roll my own?
I'm looking at iteratee as a way to replace my erroneous and really inefficient lazy-IO-based backend for an expect like Monad DSL I've been working for about 6 months or so now on and off. The problem is I want something like: expect some String send some response to block or perhaps timeout, depending on the environment, looking for some String on an input Handle, and it appears that iteratee works in a very fixed block size. Actually, it doesn't. It works with what enumerator gives him. In case of `enum_fd'[1] this is a fixed block, but generally this is a ``value'' of some ``collection''[2]. And it is up to programmer to decide of what should become a value. [1] http://okmij.org/ftp/Haskell/Iteratee/IterateeM.hs [2] http://okmij.org/ftp/papers/LL3-collections-enumerators.txt While a fixed block size is ok, if I can put back unused bytes into the enumerator somehow (I may need to put a LOT back in some cases, but in the common case I will not need to put any back as most expect-like scripts typically catch the last few bytes of data sent before the peer is blocked waiting for a response...) I don't quite get this ``last few bytes'' thing. Could you explain? I was about writing that there is no problem with putting data back to Stream, and referring to head/peek functions... But then I thought, that the ``not consuming bytes from stream'' approach may not work well in cases, when the number of bytes needed (by your function to accept/reject some rule) exceeds the size of underlying memory buffer (4K in current version of `iteratee' library[3]). [3] http://hackage.haskell.org/packages/archive/iteratee/0.3.4/doc/html/src/Data-Iteratee-IO-Fd.html Do you think that abstracting to the level of _tokens_ - instead of bytes - could help here? (Think of flex and bison.) You know, these enumerators/iteratees things can be layered into _enumeratees_[1][4]... It's just an idea. [4] http://ianen.org/articles/understanding-iteratees/ Otherwise, I'm going to want to roll my own iteratee style library where I have to say NotDone howMuchMoreIThinkINeed so I don't over consume the input stream. What's the problem with over-consuming a stream? In your case? BTW, this `NotDone' is just a ``control message'' to the chunk producer (an enumerator): IE_cont k (Just (GimmeThatManyBytes n)) Does that even make any sense? I'm kind of brainstorming in this email unfortunately :-) What's the problem with brainstorming? :) Cheers. -- vvv ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Data Structures GSoC
Nathan Hunter wrote: Hello. I am hoping to take on the Data Structures project proposed two years ago by Don Stewart herehttp://hackage.haskell.org/trac/summer-of-code/ticket/1549, this summer. Before I write up my proposal to Google, I wanted to gauge the reaction of the Haskell community to this project. Particularly: -What Data Structures in the current libraries are in most dire need of improvement? -How necessary do you think a Containers Library revision is? One thing I've seen come up repeatedly is the issue of presenting a unified and general interface for Data.Map, Data.IntMap, and related things like Data.Set, bytestring-trie, pqueue, etc which intended to mimic their interface. That alone isn't big enough for a GSoC, but it would be a very nice thing to have. Every few months there's a request on the libraries@ list to alter, generalize, or reunify the map interface in some way. ** Just to be clear, I do not mean coming up with a typeclass nor doing things like the generalized-trie tricks, I just mean a good old fashioned standard API. ** There are countervailing forces for making a good API. On the one hand we want functions to do whatever we need, on the other hand we want the API to be small enough to be usable/memorable. In the bytestring-trie library I attempted to resolve this conflict by offering a small set of highly efficient ueber-combinators in the internals module, a medium sized set of functions for standard use in the main module, and then pushed most everything else off into a convenience module. The containers library would do good to follow this sort of design. The Data.Map and Data.IntMap structures don't provide the necessary ueber-combinators, which has led to the proliferation of convenience functions which are more general than the standard use functions but not general enough to make the interface complete. Also, these generalized functions are implemented via code duplication rather than having a single implementation, which has been known to lead to cutpaste bugs and maintenance issues. Provided the correct ueber-combinators are chosen, there is no performance benefit for this code duplication either (so far as I've discovered with bytestring-trie). Additionally, it'd be nice if some of the guts were made available for public use (e.g., the bit-twiddling tricks of Data.IntMap so I don't have to duplicate them in bytestring-trie). Also it would be nice to develop a cohesive test and benchmarking suite, which would certainly be a large enough task for GSoC, though perhaps not fundable. I would be willing to co-mentor API and algorithm design for cleaning the cobwebs out of the containers library. I wouldn't have the time for mentoring the choice of datastructures or benchmarking however. -- Live well, ~wren ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: iteratee: Do I need to roll my own?
First thanks for the reply,
On Wed, Mar 31, 2010 at 11:15 AM, Valery V. Vorotyntsev valery...@gmail.com
wrote:
I'm looking at iteratee as a way to replace my erroneous and really
inefficient lazy-IO-based backend for an expect like Monad DSL I've
been working for about 6 months or so now on and off.
The problem is I want something like:
expect some String
send some response
to block or perhaps timeout, depending on the environment, looking for
some String on an input Handle, and it appears that iteratee works
in a very fixed block size.
Actually, it doesn't. It works with what enumerator gives him.
In case of `enum_fd'[1] this is a fixed block, but generally this is
a ``value'' of some ``collection''[2]. And it is up to programmer to
decide of what should become a value.
[1] http://okmij.org/ftp/Haskell/Iteratee/IterateeM.hs
[2] http://okmij.org/ftp/papers/LL3-collections-enumerators.txt
While a fixed block size is ok, if I can put back unused bytes into
the enumerator somehow (I may need to put a LOT back in some cases,
but in the common case I will not need to put any back as most
expect-like scripts typically catch the last few bytes of data sent
before the peer is blocked waiting for a response...)
I don't quite get this ``last few bytes'' thing. Could you explain?
What I mean is let's say the stream has
abcd efg abcd efg
and then I run some kind of iteratee computation looking for abcd
and the block size was fixed to cause a read 1024 bytes, but returns as much
as it can providing it to the iteratee to deal with. The iteratee, which I
want to implement Expect like behavior, would really only want to read up to
abcd consuming that from the input stream. Does the iteratee get the
whole stream that was read by the enumerator, or is it supplied a single
atomic unit at a time, such as a character, in which I can halt the
consumption of the streamed data?
What I don't want to have happen is my consuming bytes from the input
Handle, only to have them ignored, as the second instance of abcd could be
important.
I'm actually not sure that was very clear :-). I don't want to throw out
bytes by accident if that's even possible.
My discomfort with Iteratee is that most Haskell texts really want you to go
the way of lazy IO, which has led me to a good bit of trouble, and I've
never seen a very comprehensive tutorial of Iteratee available anywhere. I
am reading the Examples that come with the hackage package though.
I was about writing that there is no problem with putting data back to
Stream, and referring to head/peek functions... But then I thought,
that the ``not consuming bytes from stream'' approach may not work
well in cases, when the number of bytes needed (by your function to
accept/reject some rule) exceeds the size of underlying memory buffer
(4K in current version of `iteratee' library[3]).
[3]
http://hackage.haskell.org/packages/archive/iteratee/0.3.4/doc/html/src/Data-Iteratee-IO-Fd.html
Do you think that abstracting to the level of _tokens_ - instead of
bytes - could help here? (Think of flex and bison.) You know, these
enumerators/iteratees things can be layered into
_enumeratees_[1][4]... It's just an idea.
Now that's an interesting idea, and sort of where my previous confusing
answer seemed to be heading. I wasn't sure if the iteratee was provided a
byte, a char, or a token. If I can tell the enumerator to only send tokens
to the iteratee, (which I'd have to define), then perhaps I can ignore the
amount consumed per read, and deal with let the enumerator deal with that
buffering issue directly. Perhaps that's how iteratee really works anyway!
[4] http://ianen.org/articles/understanding-iteratees/
Otherwise, I'm going to want to roll my own iteratee style library
where I have to say NotDone howMuchMoreIThinkINeed so I don't over
consume the input stream.
What's the problem with over-consuming a stream? In your case?
Well my concern is if it's read from the input stream, and then not used,
the next time I access it, I'm not certain what's happened to the buffer.
However I suppose it's really a 2-level situation where the enumerator
pulls out some fixed chunk from a Handle or FD or what have you, and then
folds the iteratee over the buffer in some sized chunk.
In C++ I've used ideas like this example that a professor I had in college
showed me from a newsgroup he helped to moderate.
int main () {
std::cout Word count on stdin:
std::distance(std::istream_iteratorstd::string(std::cin),
std::istream_iteratorstd::string()) std::endl;
}
If the code were changed to be:
int main () {
std::cout Character count on stdin:
std::distance(std::istreambuf_iteratorchar(std::cin),
std::istreambuf_iteratorchar()) std::endl;
}
We get different behavior out of the upper level distance algorithm due to
the kind of iterator, while distance does a form of folding over the
iterators, but it's actually
Re: [Haskell-cafe] Do I need to roll my own?
David Leimbach leim...@gmail.com writes:
to block or perhaps timeout, depending on the environment, looking for
some String on an input Handle, and it appears that iteratee works
in a very fixed block size. While a fixed block size is ok, if I can
put back unused bytes into the enumerator somehow (I may need to put a
LOT back in some cases, but in the common case I will not need to put
any back as most expect-like scripts typically catch the last few
bytes of data sent before the peer is blocked waiting for a
response...)
See IterGV from the iteratee lib:
http://hackage.haskell.org/packages/archive/iteratee/0.3.1/doc/html/Data-Iteratee-Base.html#t%3AIterGV
The second argument to the Done constructor is for the portion of the
input that you didn't use. If you use the Monad instance, the unused
input is passed on (transparently) to the next iteratee in the chain.
If you use attoparsec-iteratee
(http://hackage.haskell.org/packages/archive/attoparsec-iteratee/0.1/doc/html/Data-Attoparsec-Iteratee.html),
you could write expect as an attoparsec parser:
{-# LANGUAGE OverloadedStrings #-}
import Control.Applicative
import Control.Monad.Trans (lift)
import Data.Attoparsec hiding (Done)
import Data.Attoparsec.Iteratee
import qualified Data.ByteString as S
import Data.ByteString (ByteString)
import Data.Iteratee
import Data.Iteratee.IO.Fd
import Data.Iteratee.WrappedByteString
import Data.Word (Word8)
import System.IO
import System.Posix.IO
expect :: (Monad m) = ByteString
- IterateeG WrappedByteString Word8 m ()
expect s = parserToIteratee (p return ())
where
p = string s | (anyWord8 p)
dialog :: (Monad m) =
IterateeG WrappedByteString Word8 m a -- ^ output end
- IterateeG WrappedByteString Word8 m ()
dialog outIter = do
expect login:
respond foo\n
expect password:
respond bar\n
return ()
where
respond s = do
_ - lift $ enumPure1Chunk (WrapBS s) outIter = run
return ()
main :: IO ()
main = do
hSetBuffering stdin NoBuffering
hSetBuffering stdout NoBuffering
enumFd stdInput (dialog output) = run
where
output = IterateeG $ \chunk -
case chunk of
(EOF _)- return $ Done () chunk
(Chunk (WrapBS s)) - S.putStr s
hFlush stdout
return (Cont output Nothing)
Usage example:
$ awk 'BEGIN { print login:; fflush(); system(sleep 2); \
print password:; fflush(); }' | runhaskell Expect.hs
foo
bar
N.B. for some reason enumHandle doesn't work here w.r.t buffering, had
to go to POSIX i/o to get the proper buffering behaviour.
G
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Re: [Haskell-cafe] Do I need to roll my own?
On Wed, Mar 31, 2010 at 12:02 PM, Gregory Collins
g...@gregorycollins.netwrote:
David Leimbach leim...@gmail.com writes:
to block or perhaps timeout, depending on the environment, looking for
some String on an input Handle, and it appears that iteratee works
in a very fixed block size. While a fixed block size is ok, if I can
put back unused bytes into the enumerator somehow (I may need to put a
LOT back in some cases, but in the common case I will not need to put
any back as most expect-like scripts typically catch the last few
bytes of data sent before the peer is blocked waiting for a
response...)
See IterGV from the iteratee lib:
http://hackage.haskell.org/packages/archive/iteratee/0.3.1/doc/html/Data-Iteratee-Base.html#t%3AIterGV
The second argument to the Done constructor is for the portion of the
input that you didn't use. If you use the Monad instance, the unused
input is passed on (transparently) to the next iteratee in the chain.
If you use attoparsec-iteratee
(
http://hackage.haskell.org/packages/archive/attoparsec-iteratee/0.1/doc/html/Data-Attoparsec-Iteratee.html
),
you could write expect as an attoparsec parser:
{-# LANGUAGE OverloadedStrings #-}
import Control.Applicative
import Control.Monad.Trans (lift)
import Data.Attoparsec hiding (Done)
import Data.Attoparsec.Iteratee
import qualified Data.ByteString as S
import Data.ByteString (ByteString)
import Data.Iteratee
import Data.Iteratee.IO.Fd
import Data.Iteratee.WrappedByteString
import Data.Word (Word8)
import System.IO
import System.Posix.IO
expect :: (Monad m) = ByteString
- IterateeG WrappedByteString Word8 m ()
expect s = parserToIteratee (p return ())
where
p = string s | (anyWord8 p)
dialog :: (Monad m) =
IterateeG WrappedByteString Word8 m a -- ^ output end
- IterateeG WrappedByteString Word8 m ()
dialog outIter = do
expect login:
respond foo\n
expect password:
respond bar\n
return ()
where
respond s = do
_ - lift $ enumPure1Chunk (WrapBS s) outIter = run
return ()
main :: IO ()
main = do
hSetBuffering stdin NoBuffering
hSetBuffering stdout NoBuffering
enumFd stdInput (dialog output) = run
where
output = IterateeG $ \chunk -
case chunk of
(EOF _)- return $ Done () chunk
(Chunk (WrapBS s)) - S.putStr s
hFlush stdout
return (Cont output Nothing)
Usage example:
$ awk 'BEGIN { print login:; fflush(); system(sleep 2); \
print password:; fflush(); }' | runhaskell Expect.hs
foo
bar
N.B. for some reason enumHandle doesn't work here w.r.t buffering, had
to go to POSIX i/o to get the proper buffering behaviour.
That's pretty neat actually. I'm going to have to incorporate timeouts
into something like that (and attoparsec-iteratee doesn't install for me for
some reason, I'll try again today).
That leads me to another question in another thread I'm about to start.
Dave
G
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Re: [Haskell-cafe] building encoding on Windows?
Han Joosten wrote: The haskell platform should take care of a lot of installation pain, specially for the non-technical users. I note with dismay that there's a proposal to remove OpenGL from HP. Assuming this gets approved, that'll be one less library that you can use on Windows. I thought the idea of HP was to add new stuff, not remove existing stuff... A new version is due to be release pretty soon (somewhere begin april). It has Mingw and Msys included, and also some pre-built binaries like cabal and haddock. Plain GHC has included Haddock for a while now. It seems to me that including the entirity of MinGW and MSYS is overkill, but what do I know about the matter? I was however under the impression that to use Unix emulators such as these, you have to run everything from a seperate shell rather than the usual Windows shell. It should be possible for a lot of packages to say 'cabal install package' at the command prompt to get your package up and running. I think that this is pretty cool, and most non-technical users should be able to get this to work without a lot of pain. Having gone through the pain of setting up OpenSUSE and convincing it to install GHC, it was quite impressive to use. On Linux, it seems you can actually type cabal install zlib and reasonably expect it to actually work. Typically, it'll crash and say install zlib-devel. You install that, rerun the command, and somehow it knows that you've installed the headers and where you've put them, and It Just Works(tm). Which is quite impressive. What isn't impressive is that if you ask to install something, and one of its dependencies fails to build, the failure message will get burried in amoungst several pages of other stuff. At the end it will say something like package Foo failed to build. The build failure was: exit code 1. Yeah, that's really helpful. Fortunately, if you just rebuild, it will only try to rebuild the missing dependences, so you can usually catch the real error message scroll past (invariably some C headers not installed). I also have a personal wish that more tools would make use of coloured text output to make it easier to see what's happening in the sea of text scrolling past. (We even have a fully portable Haskell library for doing this - and it even builds cleanly on Windows!) My hope is that the more useful C libraries will get added to HP so that I can start using them. (E.g., I'd love to be able to do sound synthesis using Haskell, but there aren't any libraries for accessing the sound hardware...) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Do I need to roll my own?
On Wed, Mar 31, 2010 at 12:24 PM, David Leimbach leim...@gmail.com wrote:
On Wed, Mar 31, 2010 at 12:02 PM, Gregory Collins g...@gregorycollins.net
wrote:
David Leimbach leim...@gmail.com writes:
to block or perhaps timeout, depending on the environment, looking for
some String on an input Handle, and it appears that iteratee works
in a very fixed block size. While a fixed block size is ok, if I can
put back unused bytes into the enumerator somehow (I may need to put a
LOT back in some cases, but in the common case I will not need to put
any back as most expect-like scripts typically catch the last few
bytes of data sent before the peer is blocked waiting for a
response...)
See IterGV from the iteratee lib:
http://hackage.haskell.org/packages/archive/iteratee/0.3.1/doc/html/Data-Iteratee-Base.html#t%3AIterGV
The second argument to the Done constructor is for the portion of the
input that you didn't use. If you use the Monad instance, the unused
input is passed on (transparently) to the next iteratee in the chain.
If you use attoparsec-iteratee
(
http://hackage.haskell.org/packages/archive/attoparsec-iteratee/0.1/doc/html/Data-Attoparsec-Iteratee.html
),
you could write expect as an attoparsec parser:
{-# LANGUAGE OverloadedStrings #-}
import Control.Applicative
import Control.Monad.Trans (lift)
import Data.Attoparsec hiding (Done)
import Data.Attoparsec.Iteratee
import qualified Data.ByteString as S
import Data.ByteString (ByteString)
import Data.Iteratee
import Data.Iteratee.IO.Fd
import Data.Iteratee.WrappedByteString
import Data.Word (Word8)
import System.IO
import System.Posix.IO
expect :: (Monad m) = ByteString
- IterateeG WrappedByteString Word8 m ()
expect s = parserToIteratee (p return ())
where
p = string s | (anyWord8 p)
dialog :: (Monad m) =
IterateeG WrappedByteString Word8 m a -- ^ output end
- IterateeG WrappedByteString Word8 m ()
dialog outIter = do
expect login:
respond foo\n
expect password:
respond bar\n
return ()
where
respond s = do
_ - lift $ enumPure1Chunk (WrapBS s) outIter = run
return ()
main :: IO ()
main = do
hSetBuffering stdin NoBuffering
hSetBuffering stdout NoBuffering
enumFd stdInput (dialog output) = run
where
output = IterateeG $ \chunk -
case chunk of
(EOF _)- return $ Done () chunk
(Chunk (WrapBS s)) - S.putStr s
hFlush stdout
return (Cont output Nothing)
Usage example:
$ awk 'BEGIN { print login:; fflush(); system(sleep 2); \
print password:; fflush(); }' | runhaskell Expect.hs
foo
bar
N.B. for some reason enumHandle doesn't work here w.r.t buffering, had
to go to POSIX i/o to get the proper buffering behaviour.
That's pretty neat actually. I'm going to have to incorporate timeouts
into something like that (and attoparsec-iteratee doesn't install for me for
some reason, I'll try again today).
worked fine today...
That leads me to another question in another thread I'm about to start.
And that other thread is not going to happen, because I realized I was just
having issues with non-strict vs strict evaluation :-) It makes perfect
sense now...
gist is:
timeout (10 ^ 6) $ return $ sum [1..]
and
timeout (10 ^ 6) $! return $ sum [1..]
will not timeout, and will hang while
timeout (10 ^ 6) $ return $! sum [1..]
does timeout... and everything in the Haskell universe is nice and
consistent.
Dave
Dave
G
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[Haskell-cafe] Hughes' parallel annotations for fixing a space leak
Dear haskell-cafe, I've been thinking about space leaks lately. In particular, I've been studying the tricky example with pairs break [] = ([],[]) break (x:xs) = if x == '\n' then ([],xs) else (x:ys,zs) where (ys,zs) = break xs which was discussed in the papers Jan Sparud. Fixing some space leaks without a garbage collector. http://bit.ly/cOxcVJ Philip Wadler. Fixing some space leaks with a garbage collector. http://homepages.inf.ed.ac.uk/wadler/topics/garbage-collection.html As I understand it, GHC implements the technique from Sparud's paper, so this is a solved problem. (It will only kick in when compiled with optimization, though, so -O0 will make the above leak in GHC 6.10.4 if I checked that correctly.) Now, I'm wondering about alternative solutions. Wadler mentions some sort of parallel combinators break xs = (PAR before '\n' ys, PAR after '\n' zs) where (ys,zs) = SYNCLIST xs which were introduced by John Hughes in his Phd thesis from 1983. They are intriguing! Unfortunately, I haven't been able to procure a copy of Hughes' thesis, either electronic or in paper. :( Can anyone help? Are there any other resources about this parallel approach? Regards, Heinrich Apfelmus -- http://apfelmus.nfshost.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Shootout update
On Mar 30, 1:26 am, Simon Marlow marlo...@gmail.com wrote: The shootout (sorry, Computer Language Benchmarks Game) ... In a different time, in a different place, the shootout meant a football once again flying over the cross bar or harmlessly into the arms of the keeper and England once more exiting an international competition. Here in the west it has meant slaughter - back in 2004 crossed-pistols were suggested as the website image. Wading through Google search results comprised of porn sites and college mass murder just wasn't a bright happy start to the day for me - so after Virginia Tech I changed the name. I should probably have moved everything to a new project (a new URL). ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] cabal through PHPProxy
i'm using PHPProxy to go on the internet (www.phpproxy.fr). How can i tell cabal to use this? ... PHPProxy is a web based proxy. To use it, you have to type the http address you want in a field on the page. You still need some web access in order to access a web-based proxy... Is www.phpproxy.fr the only outer site you can connect directly to? I am just curious of what kind of LAN you have got. :) How do you update your OS, anyway? How do you download files? * * * Try the following: # Download phpproxy wget -c 'http://idea.hosting.lv/a/phpproxy/phpproxy-0.6.tar.gz' # Unpack tar -xzf phpproxy-0.6.tar.gz # Launch PHPProxy client cd phpproxy-0.6 python phpproxy.py # In another terminal, try running cabal with `http_proxy' http_proxy=http://localhost:8080/ cabal update --verbose=3 Please, report your progress. Good luck! -- vvv ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Do I need to roll my own?
Hi Dave, From: David Leimbach leim...@gmail.com I'm looking at iteratee as a way to replace my erroneous and really inefficient lazy-IO-based backend for an expect like Monad DSL I've been working for about 6 months or so now on and off. The problem is I want something like: expect some String send some response to block or perhaps timeout, depending on the environment, looking for some String on an input Handle, and it appears that iteratee works in a very fixed block size. While a fixed block size is ok, if I can put back unused bytes into the enumerator somehow (I may need to put a LOT back in some cases, but in the common case I will not need to put any back as most expect-like scripts typically catch the last few bytes of data sent before the peer is blocked waiting for a response...) I'm quite sure I don't know what you're trying to do. The only time I can think of needing this is if you're running an iteratee on a file handle, keeping the handle open, then running another iteratee on it. Is this what you're doing? If so, I would make a new run function: runResidue :: (Monad m, SC.StreamChunk s el) = IterateeG s el m a - m (a, s) runResidue iter = runIter iter (EOF Nothing) = \res - case res of Done x s - return (x, s) Cont _ e - error $ control message: ++ show e This function will return the unused portion of the stream, then you can do this: enumResidue :: Handle - s - EnumeratorGM s el m a enumResidue h s = enumPure1Chunk s . enumHandle h Is this what you need? If I'm completely wrong about what you're trying to do (or you're using multiple threads), there are other options. You also may want to look at iteratee-HEAD. The implementation has been cleaned up a lot, the block sizes are user-specified, and there's an exception-based, user-extensible mechanism for iteratees to alter enumerator behavior. Sincerely, John ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Do I need to roll my own?
On Wed, Mar 31, 2010 at 2:12 PM, John Lato jwl...@gmail.com wrote: Hi Dave, From: David Leimbach leim...@gmail.com I'm looking at iteratee as a way to replace my erroneous and really inefficient lazy-IO-based backend for an expect like Monad DSL I've been working for about 6 months or so now on and off. The problem is I want something like: expect some String send some response to block or perhaps timeout, depending on the environment, looking for some String on an input Handle, and it appears that iteratee works in a very fixed block size. While a fixed block size is ok, if I can put back unused bytes into the enumerator somehow (I may need to put a LOT back in some cases, but in the common case I will not need to put any back as most expect-like scripts typically catch the last few bytes of data sent before the peer is blocked waiting for a response...) I'm quite sure I don't know what you're trying to do. The only time I can think of needing this is if you're running an iteratee on a file handle, keeping the handle open, then running another iteratee on it. Is this what you're doing? If so, I would make a new run function: runResidue :: (Monad m, SC.StreamChunk s el) = IterateeG s el m a - m (a, s) runResidue iter = runIter iter (EOF Nothing) = \res - case res of Done x s - return (x, s) Cont _ e - error $ control message: ++ show e This function will return the unused portion of the stream, then you can do this: enumResidue :: Handle - s - EnumeratorGM s el m a enumResidue h s = enumPure1Chunk s . enumHandle h Is this what you need? If I'm completely wrong about what you're trying to do (or you're using multiple threads), there are other options. The problem is I am not sure what it was I needed to get started to begin with. For a moment it seemed that I could be throwing out data that's been read, but not yet fed to an iteratee step. If that's not the case, I'll never need to put back any characters. The attoparsec-iteratee example posted, plus some experimentation has led me to believe I don't need to worry about this sort of thing for the kind of processing I'm looking to do. You also may want to look at iteratee-HEAD. The implementation has been cleaned up a lot, the block sizes are user-specified, and there's an exception-based, user-extensible mechanism for iteratees to alter enumerator behavior. That's very compelling. Here's the properties of the system I'm trying to build (in fact I've built this system with Haskell already months ago, but trying to evaluate if iteratee can fix problems I've got now) 1. Must have an expect-like language to a subprocess over a pair of Handles such that I can query what is normally a command line interface as a polling refresher thread to a cache. Note that there may be many sub-processes with a poller/cache (up to 6 so far). Data produced is dumped as records to stdout from each thread such that the process that spawned this haskell program can parse those records and update it's view of this particular part of the world. 2. Must be able to interleave commands between polled record data from the processes in 1. These commands come in over this process's stdin from the program that started the Haskell program. 3. The polling process in 1, must be able to respond to a timeout situation. In this system, a cable could become disconnected or a part of the system could become unavailable, or a part of the system underneath could become unreliable and require a restart to guarantee the serviceability of the whole system. I have 1 and 2 working fine in a current iteration of the system, but because we're dealing with a pretty complex stack, 3 is really necessary too, and I've conquered my timeout issues from earlier in a reasonable enough way. The problem is that the timeout handler apparently runs into problems that I think stem from lazyIO not having been evaluated on a handle yet, but the timeout handler has invalidated that handle, and then that thunk, which was partially applied, is now talking to some broken value. As far as I know, I can't go back and prevent previously bound thunks that have the wrong handle from executing, if that is truly what's happening. What I'd like to do is prevent that situation from ever happening to begin with, or at least rule it out. I'm hoping version 2 of this system to be based on iteratee and avoid this sort of problem at all. The alternative is to write this in another language, but that throws out a lot of nice and simple code that's present in the non IO bits of this code, for dealing with parsing and data serialization. Dave Sincerely, John ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: iteratee: Do I need to roll my own?
On Wed, Mar 31, 2010 at 7:42 PM, David Leimbach leim...@gmail.com wrote: What I mean is let's say the stream has abcd efg abcd efg and then I run some kind of iteratee computation looking for abcd You could adapt the 'heads' function from the iteratee package to do this: http://hackage.haskell.org/packages/archive/iteratee/0.3.4/doc/html/src/Data-Iteratee-Base.html#heads and the block size was fixed to cause a read 1024 bytes, but returns as much as it can providing it to the iteratee to deal with. The iteratee, which I want to implement Expect like behavior, would really only want to read up to abcd consuming that from the input stream. Does the iteratee get the whole stream that was read by the enumerator, or is it supplied a single atomic unit at a time, such as a character, in which I can halt the consumption of the streamed data? The iteratee will be applied to the whole stream that was read by the enumerator. You should ensure that the part of this input stream which is not needed for the result is saved in the 'Done' constructor so that other iteratees may consume it. What I don't want to have happen is my consuming bytes from the input Handle, only to have them ignored, as the second instance of abcd could be important. Note that an IterateeG has an instance for Monad which allows you to sequentially compose iteratees. If you write a 'match' iteratee (by adapting the 'heads' function I mentioned earlier which matches a given string against the first part of a stream) you can compose these sequentially: foo = match abcd match efg foo The first match will be applied to the stream that was read by the enumerator. It will consume the abcd and saves the rest of the stream (in the 'Done' constructor). The second match will first be applied to the saved stream from the first match. If this stream was not big enough the iteratee will ask for more (using the 'Cont' constructor). The enumerator will then do a second read and applies the continuation (stored in the 'Cont' constructor) to the new stream. You may also consider using actual parser combinators build on top of iteratee: http://hackage.haskell.org/package/attoparsec-iteratee http://hackage.haskell.org/package/iteratee-parsec (I typed this in a hurry so some things may be off a bit) regards, Bas ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Seeking advice about monadic traversal functions
Heinrich,
Thanks for your excellent response! Indeed, it was the rebuilding of the
tree that had me stumped. I also see the benefits of using the lift
functions, thanks again for this insight.
Darryn.
On Wed, 2010-03-31 at 12:44 +0200, Heinrich Apfelmus wrote:
Darryn Reid wrote:
I've coded a (fairly) general rewriting traversal - I suspect the
approach might be generalisable to all tree-like types, but this doesn't
concern me much right now. My purpose is for building theorem provers
for a number of logics, separating the overall control mechanism from
the specific rules for each logic.
The beauty of Haskell here is in being able to abstract the traversal
away from the specific reduction rules and languages of the different
logics. I have paired down the code here to numbers rather than modal
formulas for the sake of clarity and simplicity. My question is
two-fold:
1. Does my representation of the traversal seem good or would it be
better expressed differently? If so, I'd appreciate the thoughts of more
experienced Haskell users.
Looks fine to me, though I have no experience with tree
rewriting. :) I'd probably write it like this:
data Tableau a = Nil -- End of a path
| Single a (Tableau a) -- Conjunction
| Fork (Tableau a) (Tableau a) -- Disjunction
deriving (Eq, Show)
data Action = Cut | Next
type Rewriter m a = Tableau a - m (Tableau a, Action)
rewrite :: (Monad m) = Rewriter m a - Tableau a - m (Tableau a)
rewrite f t = f t = (uncurry . flip) go
where
go Cut t = return t
go Next Nil = return Nil
go Next (Single x t1) = liftM (Single x) (rewrite f t1)
go Next (Fork t1 t2 ) = liftM2 Fork (rewrite f t1)
(rewrite f t2)
In particular, liftM and liftM2 make it apparent that we're just
wrapping the result in a constructor.
In case you want more flexibility in moving from children to parents,
you may want to have a look at zippers
http://en.wikibooks.org/wiki/Haskell/Zippers
2. I cannot really see how to easily extend this to a queue-based
breadth-first traversal, which would give me fairness. I'm sure others
must have a good idea of how to do what I'm doing here except in
breadth-first order; I'd appreciate it very much if someone could show
me how to make a second breadth-first version.
This is more tricky than I thought! Just listing the nodes in
breadth-first order is straightforward, but the problem is that you
also want to build the result tree. Depth-first search follows the tree
structure more closely, so building the result was no problem.
The solution is to solve the easy problem of listing all nodes
in breadth-first order first, because it turns out that it's possible to
reconstruct the result tree from such a list! In other words, it's
possible to run breadth-first search in reverse, building the tree from
a list of nodes.
How exactly does this work? If you think about it, the analogous problem
for depth-first search is not too difficult, you just walk through the
list of nodes and build a stack; pushing Nil nodes and combining the
top two items when encountering Fork nodes. So, for solving the
breadth-first version, the idea is to build a queue instead of a stack.
The details of that are a bit tricky of course, you have to be careful
when to push what on the queue. But why bother being careful if we have
Haskell? I thus present the haphazardly named:
Lambda Fu, form 132 - linear serpent inverse
The idea is to formulate breadth-first search in a way that is *trivial*
to invert, and the key ingredient to that is a *linear* function, i.e.
one that never discards or duplicates data, but only shuffles it around.
Here is what I have in mind:
{-# LANGUAGE ViewPatterns #-}
import Data.Sequence as Seq -- this will be our queue type
import Data.List as List
type Node a = Tableau a -- just a node without children (ugly type)
type State a = ([Action],[(Action,Node a)], Seq (Tableau a))
queue (_,_,q) = q
nodes (_,l,_) = l
analyze :: State a - State a
analyze (Cut :xs, ts, viewl - t : q) =
(xs, (Cut , t ) : ts, q )
analyze (Next:xs, ts, viewl - Nil : q) =
(xs, (Next, Nil ) : ts, q )
analyze (Next:xs, ts, viewl - Single x t1 : q) =
(xs, (Next, Single x u) : ts, q | t1 )
analyze (Next:xs, ts, viewl - Fork t1 t2 : q) =
(xs, (Next, Fork u u ) : ts, (q | t1) | t2 )
u = Nil -- or undefined
bfs xs t = nodes $
until (Seq.null . queue) analyze (xs,[],singleton t)
So, bfs just applies analyze repeatedly on a suitable state which
includes the queue, the list of nodes in breadth-first order and a
stream of actions. (This is
[Haskell-cafe] [OT?] Haskell-inspired functions for BASH
Hi all, I've been studying Haskell for about a year now, and I've really come to like it. In my daily work I write a lot of BASH shell scripts and I thought I'd try add some of the haskell features and constructs to BASH to make my scripting life a bit easier. So I've been working on a small BASH function library that implements some basic functional programming building blocks. Note: There is no actual Haskell code involved here. I put up the full manpage here: http://hpaste.org/fastcgi/hpaste.fcgi/view?id=24564 Source is here: http://svn.solucorp.qc.ca/repos/solucorp/bashkell/trunk/trunk/ All this is very prototypical, but here is an example of some of the stuff I've got so far (map, filter, foldr): $ ls data 1.txt 2.txt # basic map, argument goes on the command line $ ls -d data/* | map basename 1.txt 2.txt # map with lambda expression $ ls -d data/* | map '\f - basename $f .txt' 1 2 # simple filter, also works with lambda $ ls -d data/* | map basename | filter 'test 1.txt =' 1.txt # sum $ ls -d data/* | map '\f - basename $f .txt' | foldr '\x acc - echo $(($x + $acc))' 0 3 Basically I'm looking for a bit of feedback/info: - Does anyone know if there are already similar projets out there? - Does anyone find this interesting? - Any other comment/suggestion/feedback - Where's a good place to promote such a project? Thanks a lot, Patrick LeBoutillier -- = Patrick LeBoutillier Rosemère, Québec, Canada ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] [OT?] Haskell-inspired functions for BASH
On 1 April 2010 11:05, Patrick LeBoutillier patrick.leboutill...@gmail.com wrote: Basically I'm looking for a bit of feedback/info: - Does anyone know if there are already similar projets out there? On Hackage: LambdaShell, language-sh, HSH, Hashell (dead), only, Shellac Note that not all of these might be directly similar: I found them by doing a quick search for shell and looking in the console section. -- 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
[Haskell-cafe] Haskell on Debian
I tend to install haskell packages from apt whenever possible. One such package is unix, which appears to come provided by the ghc6 debian package. I'm trying to cabal install lambdabot and getting the following: $ cabal install lambdabot Resolving dependencies... Configuring lambdabot-4.2.2.1... Preprocessing executables for lambdabot-4.2.2.1... Building lambdabot-4.2.2.1... Main.hs:11:7: Could not find module `System.Posix.Signals': It is a member of the hidden package `unix-2.4.0.0'. Perhaps you need to add `unix' to the build-depends in your .cabal file. Use -v to see a list of the files searched for. cabal: Error: some packages failed to install: lambdabot-4.2.2.1 failed during the building phase. The exception was: ExitFailure 1 I have a feeling this has something to do with the interaction between cabal and apt... Does anyone have any advice for fixing this issue other than just adding unix to the lambdabot.cabal file? -- Alex R ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Haskell on Debian
On 1 April 2010 11:42, Alex Rozenshteyn rpglove...@gmail.com wrote: Main.hs:11:7: Could not find module `System.Posix.Signals': It is a member of the hidden package `unix-2.4.0.0'. Perhaps you need to add `unix' to the build-depends in your .cabal file. Interesting, because unix _is_ listed in build-depends in the .cabal file for lambdabot. Does ghc-pkg check complain about unix? Does ghc-pkg list unix say it's there? I have a feeling this has something to do with the interaction between cabal and apt... Highly unlikely unless there's an inconsistency in the packages on your system. -- 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] Haskell on Debian
$ ghc-pkg check outputs nothing $ ghc-pkg list unix /var/lib/ghc-6.12.1/package.conf.d unix-2.4.0.0 /home/alex/.ghc/x86_64-linux-6.12.1/package.conf.d unix appears to be in the build-depends of the Library, but not in the build-depends of Executable lambdabot Adding unix to the second build-depends appears to fix the error (but now it complains that base is hidden). On Wed, Mar 31, 2010 at 8:48 PM, Ivan Miljenovic ivan.miljeno...@gmail.comwrote: On 1 April 2010 11:42, Alex Rozenshteyn rpglove...@gmail.com wrote: Main.hs:11:7: Could not find module `System.Posix.Signals': It is a member of the hidden package `unix-2.4.0.0'. Perhaps you need to add `unix' to the build-depends in your .cabal file. Interesting, because unix _is_ listed in build-depends in the .cabal file for lambdabot. Does ghc-pkg check complain about unix? Does ghc-pkg list unix say it's there? I have a feeling this has something to do with the interaction between cabal and apt... Highly unlikely unless there's an inconsistency in the packages on your system. -- Ivan Lazar Miljenovic ivan.miljeno...@gmail.com IvanMiljenovic.wordpress.com -- Alex R ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] why doesn't time allow diff of localtimes ?
On Wed, 31 Mar 2010 01:32:56 -0400 wagne...@seas.upenn.edu wrote: Two values of LocalTime may well be computed with respect to different timezones, which makes the operation you ask for dangerous. First convert to UTCTime (with localTimeToUTC), then compare. that makes sense. unfortunately getting the current timezone to convert to UTC results in the dreaded IO contamination problem... Brian ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Trying to figure out a segfault caused by haskeline.
Hi,
Nobody seems to have any idea what is happening yet. Though thanks for
trying dagit (forgot to add haskell-cafe to my repliess to him).
Quick update incase it helps, compiling with profiling and running with the
-xc option results in,
Main.CAF:runInputT_rOASystem.Posix.Files.CAFSegmentation fault
I'm still working on it but could it be the configuration file? thats the
thing the haskeline accesses files for right?
On Mon, Mar 29, 2010 at 8:28 PM, ryan winkelmaier syfra...@gmail.comwrote:
Hey everyone,
I'm looking for help with a seg fault that takes out both my ghci and darcs
as well as anything that uses haskeline. A bug on the haskeline trac hasn't
gotten any response so I figured I might as well figure this out myself and
get ghci up and running again.
Using the test program below I get the same segmentation fault, so I run it
using gdb and get the following,
Program received signal SIGSEGV, Segmentation fault.
0x0053fdce in base_ForeignziCziString_zdwa_info ()
My knowledge of this is very limited from here on out so here is what I was
able to get together.
On the 20th call of base_ForeignziCziString_zdwa_info
r14 is 0 so
0x0053fdce +22:movsbq (%r14),%rax
produces the segfault.
From what I understand this is happening in the Foreign.C.String module but
thats as much as I know.
Anyone have advice on where to go next?
System info:
Distribution: gentoo amd64
Ghc version: currently 6.12.1 (though the segfault happends on any of the
ones with haskeline)
Haskeline version: 0.6.2.2
Here is the test program
module Main where
import System.Console.Haskeline
import System.Environment
{--
Testing the line-input functions and their interaction with ctrl-c signals.
Usage:
./Test (line input)
./Test chars(character input)
--}
mySettings :: Settings IO
mySettings = defaultSettings {historyFile = Just myhist}
main :: IO ()
main = do
args - getArgs
let inputFunc = case args of
[chars] - fmap (fmap (\c - [c])) . getInputChar
_ - getInputLine
runInputT mySettings $ withInterrupt $ loop inputFunc 0
where
loop inputFunc n = do
minput - handleInterrupt (return (Just Caught interrupted))
$ inputFunc (show n ++ :)
case minput of
Nothing - return ()
Just quit - return ()
Just q - return ()
Just s - do
outputStrLn (line ++ show n ++ : ++ s)
loop inputFunc (n+1)
Syfran
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[Haskell-cafe] Re: why doesn't time allow diff of localtimes ?
On Wed, 2010-03-31 at 19:29 -0700, bri...@aracnet.com wrote: On Wed, 31 Mar 2010 01:32:56 -0400 wagne...@seas.upenn.edu wrote: Two values of LocalTime may well be computed with respect to different timezones, which makes the operation you ask for dangerous. First convert to UTCTime (with localTimeToUTC), then compare. that makes sense. unfortunately getting the current timezone to convert to UTC results in the dreaded IO contamination problem... Brian Hmm. Where do you get the local times from in the first place? Regards PS. As the timezone can change in runtime (like change from summer time to standard or simply crossing the 'border' with laptop) I don't think that there is escape from IO. 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] Re: why doesn't time allow diff of localtimes ?
On Thu, 01 Apr 2010 06:20:25 +0200 Maciej Piechotka uzytkown...@gmail.com wrote: On Wed, 2010-03-31 at 19:29 -0700, bri...@aracnet.com wrote: On Wed, 31 Mar 2010 01:32:56 -0400 wagne...@seas.upenn.edu wrote: Two values of LocalTime may well be computed with respect to different timezones, which makes the operation you ask for dangerous. First convert to UTCTime (with localTimeToUTC), then compare. that makes sense. unfortunately getting the current timezone to convert to UTC results in the dreaded IO contamination problem... Brian Hmm. Where do you get the local times from in the first place? read it from a file of course :-) I think I've got it figured out. it's not too ugly. One interesting hole in the system is that buildTime can return a LocalTime _or_ a UTCTime. That means the same string used to generate a time can give you two different times. It seems as thought it should be restricted to always returning a UTCTime. If it's going to return a local time it should require an extra argument of a timezone, shouldn't it ? Brian ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] ANN: logfloat 0.12.1
-- logfloat 0.12.1 This package provides a type for storing numbers in the log-domain, primarily useful for preventing underflow when multiplying many probabilities as in HMMs and other probabilistic models. The package also provides modules for dealing with floating numbers correctly. -- Changes since 0.12.0.1 * Fixed a number of bugs where LogFloat values would become NaN when they should not. These bugs involved using normal-space positive infinity and so would not affect clients using the package for probabilities. The fixes do introduce some extra checks though. If anyone is using the package for probabilities in a large enough project and could run some benchmarks to see how 0.12.1 compares to 0.12.0.1 I'd love to hear the results. (I'm not sure that doing microbenchmarks would actually give much insight about real programs.) If the overhead is bad enough I can add a LogProb type which ensures things are proper probabilities in order to avoid the new checks. -- Compatibility / Portability The package is compatible with Hugs (September 2006) and GHC (6.8, 6.10, 6.12). For anyone still using GHC 6.6, the code may still work if you replace LANGUAGE pragma by equivalent OPTIONS_GHC pragma. The package is not compatible with nhc98 and Yhc because Data.Number.RealToFrac uses MPTCs. The other modules should be compatible. -- Links Homepage: http://code.haskell.org/~wren/ Hackage: http://hackage.haskell.org/cgi-bin/hackage-scripts/package/logfloat Darcs: http://code.haskell.org/~wren/logfloat/ Haddock (Darcs version): http://code.haskell.org/~wren/logfloat/dist/doc/html/logfloat/ -- Live well, ~wren ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
