Re: [Haskell-cafe] Graphical graph reduction
dainichi wrote: Now to the point: Wouldn't it be great if I had a visual tool that visually showed me the graph while the above evaluation unfolded? I could use it to show some of my co-workers to whom laziness is a mystery, what it's all about. Check out http://thyer.name/lambda-animator/. Requires Java. Explores several forms of laziness and them some. -- View this message in context: http://www.nabble.com/Graphical-graph-reduction-tp15637156p15649433.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
[Haskell-cafe] Haskell w/ delimited continuations
Call-by-name lambda-calculus is strictly more expressive (in Felleisen sense) than call-by-value lambda-calculus, and the call-by-need (aka, lazy) lambda-calculus is observationally equivalent to the call-by-name. One can add shift/reset to any of these calculi (CBV shift/reset is most known; there are several CBN shift/reset, including the one I'm particularly attached to; in principle one can add shift/reset to call-by-need). Adding control effects (shift/reset) changes the expressivity results. Now all three calculi are distinct and none subsumes the other. For example, the expression reset( (\x - 1) (abort 2)) evaluates to 1 in call-by-name and evaluate to 2 in call-by-value. The expression reset ((\x - x + x) (shift f f)) has the type int-int in call-by-need (it is a function \x - x + x) and it has the type int-int-int in call-by-name (and it is the curried addition function). The fact that call-by-need is no longer observationally equivalent to call-by-name and sharing becomes observable is the most distressing. It disables many optimizations GHC is allowed to do. Types help: there are call-by-name calculi with shift/reset with effect typing; one can look at the type and see what control effect an expression may make. That will still permit GHC optimize pure expressions and leave effectful expressions as they are. Alas, that type system is complex and I don't think inference is decidable there due to the presence of subtyping (one must annotate at least some of the binders with types, in particular, the binders of shift). It seems the simplest solution is to confine shift/reset to a monad. Regarding purity: the obligatory reference is Amr Sabry. What is a Purely Functional Language? In J. Functional Programming, 8(1), 1-22, Jan. 1998. http://www.cs.indiana.edu/~sabry/papers/purelyFunctional.ps Please see the definition 4.7. As Matthias Blume said, a bit informally, evaluation of a pure expression should not depend on CBN or CBV or some other such strategy. By this definition, an expression that involves shift/reset is not pure, as the above examples demonstrate. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Graphical graph reduction
About 7 years ago such a tool existed: http://www.cs.kent.ac.uk/people/staff/cr3/toolbox/haskell/GHood/ I don't know if Claus is around. Perhaps he could give you more information. Dominic. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Database relations mapping
Hi,
I'm developing toy application to learn HDBC. I have problem with
doing relations mapping. Actually I don't know is it a problem or
feature. ;)
Anyway, I have two tables with relation between them:
(this example is simplified to the whole structure of database, you can imagine)
CREATE TABLE TD_set (
setId INTEGER PRIMARY KEY,
setName TEXT NOT NULL
)
CREATE TABLE TO_card (
cardId INTEGER PRIMARY KEY AUTOINCREMENT,
setId INTEGER NOT NULL, -- Relation to TD_set
setSeq INTEGER NOT NULL
)
(no foreign key as sqlite3 does not care anyway - at least AFAIK)
And in Haskell:
type CardSet = String
data Card = Card {
set :: CardSet,
seqNo:: Integer,
}
There is no problem with filling the structure Card with seqNo but I
can't fill set. I would have to put there IO (CardSet) but I don't
want to do that as whole structure returned from my mapping function
is already inside IO monad. Can I do it?
Here is my (perfect) function - http://hpaste.org/5839 . See
getCards and some helper functions. This does not compile as (I
believe) getElement wants to return IO (CardSet)
Thank you in advance for all your input.
Radek.
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Re: [Haskell-cafe] Database relations mapping
On 23 Feb 2008, at 3:30 AM, Radosław Grzanka wrote:
Hi,
I'm developing toy application to learn HDBC. I have problem with
doing relations mapping. Actually I don't know is it a problem or
feature. ;)
Anyway, I have two tables with relation between them:
(this example is simplified to the whole structure of database, you
can imagine)
CREATE TABLE TD_set (
setId INTEGER PRIMARY KEY,
setName TEXT NOT NULL
)
CREATE TABLE TO_card (
cardId INTEGER PRIMARY KEY AUTOINCREMENT,
setId INTEGER NOT NULL, -- Relation
to TD_set
setSeq INTEGER NOT NULL
)
(no foreign key as sqlite3 does not care anyway - at least AFAIK)
And in Haskell:
type CardSet = String
data Card = Card {
set :: CardSet,
seqNo:: Integer,
}
There is no problem with filling the structure Card with seqNo but I
can't fill set. I would have to put there IO (CardSet) but I don't
want to do that as whole structure returned from my mapping function
is already inside IO monad. Can I do it?
Here is my (perfect) function - http://hpaste.org/5839 . See
getCards and some helper functions. This does not compile as (I
believe) getElement wants to return IO (CardSet)
Thank you in advance for all your input.
You want to put toItem into the IO monad:
toItem [cardId, setId, setSeq] = do
set_ - getElement
return $ Card {
set = set_
seqNo= fromSql setSeq,
}
toItem x = fail (Unexpected result in getCards: ++ (show x))
Then use
mapM toItem cards
instead of
return $ map toItem cards
jcc
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[Haskell-cafe] A beginners question
Dear All, banging my head against Haskell, but liking the feeling of hurting brains. Just a simple question: If fmap (^4) [1,2,3] = \i - shows i gives 1 16 81 then why does let i = fmap (^4) [1,2,3] in shows i give [1,16,81] Probably very simple, but there must be a delicate difference between these two expressions. I just don't get it. -- Harri Kiiskinen [EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] A little toy of Haskell Trivia
There's a link on the HackageDB Introduction page that gets you the latest versions of all packages (30MB). Ross, Thanks for the archive URL. I parsed through all the hackagedb modules. I also added the display of repository source (ghc, hdb) and package source. HackageDB is 3-4 times bigger than GHC core. The result is interesting, looking at the most used modules move up and down the rank... http://haskell.ecoin.net/cgi-bin/modules.pl As I reflect on what I did, this result is kind of useful in learning Haskell. Haskell is about re-using modules and building on top of them. If a module is often used by Haskell community (especially, library writers), a beginner better understand that module first (such as Monad, List, Map, Exception, Array, etc). On the other hand, I am thinking to display a eco-system kind of graph/chart to show how the modules are connected with each other, and which module is on the top of the eco-system (either the most advanced module, or a module no one cares about!). But my data seem to have a recursive nature. I don't quite understand why nor how to get by it. Rewriting that script in Haskell could be an interesting exercise. Do you have the source code? Ben, I think the best way to write this parser in Haskell is to use haddock since haddock understands Haskell syntax much better than my hacker-style script. Here is the source code of both the parser(s) and cgi script. The code is very experimental and low-quality... Let me know if you have any question. http://haskell.ecoin.net/haskell-trivia.tgz Steve ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] A beginners question
fmap (^4) [1,2,3] = \i - shows i gives 1 16 81 You are in the list comprehension in a monadic expression. shows is called three times (i is int). then why does let i = fmap (^4) [1,2,3] in shows i give [1,16,81] shows is called once (i is a list). ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] A beginners question
On Sat, Feb 23, 2008 at 8:00 AM, Harri Kiiskinen [EMAIL PROTECTED] wrote: then why does let i = fmap (^4) [1,2,3] in shows i give [1,16,81] I'll probably mess this up somewhere, but if I do, reset assured that someone else here will correct me ;) fmap (^4) [1,2,3] == [1,16,81] so shows of that == [1,16,81] (note the trailing space), obvious I hope. However, [1,16,81] = \i - shows i operates in the list monad. I can't find the actual instance of Monad [] right now, but it will apply 'shows i ' to each element in the first list and concat the results. Since strings are just [Char], concating them is string concatenation. And so you have 1 16 81 (again, note the trailing space) AGL -- Adam Langley [EMAIL PROTECTED] http://www.imperialviolet.org ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] A beginners question
2008/2/23, Harri Kiiskinen [EMAIL PROTECTED]: Dear All, banging my head against Haskell, but liking the feeling of hurting brains. Just a simple question: If fmap (^4) [1,2,3] = \i - shows i gives 1 16 81 In the List Monad, (=) is defined as concatMap, so this code can be translated by : concatMap (\i - shows i ) (fmap (^4) [1,2,3]) shows is applied to each elements of the list, then the strings are concatened. Whereas in let xs = fmap (^4) [1,2,3] in shows xs shows is applied to the whole list. -- Jedaï ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: [Haskell] *** JOB OFFER *** [...]
Peter Verswyvelen wrote: PS: This job offer was already placed in the Haskell Café a while ago, but I was advised there to place it in the main Haskell list. I hope this is not considered as spam. I certainly don't see it as spam. One day there will be a dozen jobs for Haskell programmers on Monster or Jobserve, and at that point another such announcement *would* be spam. But at the moment it has rarity value. Paul. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] A beginners question
Harri Kiiskinen wrote: fmap (^4) [1,2,3] = \i - shows i let i = fmap (^4) [1,2,3] in shows i Probably very simple, but there must be a delicate difference between these two expressions. I just don't get it. First, let's simplify these expressions using the following equation: fmap (^4) [1,2,3] == [1,16,81] So, we have x1 = [1,16,81] = \i - shows i x2 = let i = [1,16,81] in shows i Let's examine the x2 first. We can substitute i, and obtain shows [1,16,81] note that the whole list is passed to shows. shows then prints it to a string, using the notation for lists, and adds a trailing space. Note that shows is called here with type: shows :: [Integer] - String - String Now, we consider x1. Here = is invoked for the list monad, which extracts each member 1,16,81 from the list and applies shows to them separately, and concatenates all the results. In other words, we can rewrite x1 as: shows 1 ++ shows 16 ++ shows 81 Note that here we pass single elements to shows, and not the whole list. Indeed, here we are calling shows at a different type: shows :: Integer - String - String But this is fine, since shows knows how to print Integers as well as lists of them. Concluding: the monadic bind operator = is not function application. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Graphical graph reduction
About 7 years ago such a tool existed: http://www.cs.kent.ac.uk/people/staff/cr3/toolbox/haskell/GHood/ GHood was never intended to visualize graph reduction directly (*). instead, it visualized observations - ie, you could see if and when which parts of an observed data structure was inspected during a program run, but not the reductions themselves, and definitely not sharing as in the cyclic programming example earlier in this thread. GHood was very helpful in visualizing some aspects of non-strict evaluation, and its main advantage over Hood was in observing relative strictness, dynamically: you could not only see which parts of an observed data structure were used at all, but by observing both the input and the output of a function, you could see the demands for the output drive the demands for the input. very useful for spotting strictness bugs, such as demanding too much of the input too early, instead of just as much as needed to produce just as much as used for producing the output. see the example applets on that GHood page. claus (*) it was, however, the lack of reduction animation in haskell implementations that kept me looking for such opportunities (i had grown up, functionally, with the kiel reduction systems, and their built-in support for displaying and editing intermediate reduction results, with higher-order functions, free variables, avoiding name clashes, and all, and was missing all that support in the supposedly more modern world of haskell..) an earlier, simpler, example was the use of overloading to visualize intermediate expressions, so you could see the difference between foldr and foldl, etc: http://www.cs.kent.ac.uk/people/staff/cr3/toolbox/haskell/R.hs btw, in one of the previous incarnations of this thread, Wolfram Kahl used the HOP System to generate graphical traces of term-graph reductions: http://www.cas.mcmaster.ca/~kahl/HOPS/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Haskell w/ delimited continuations
On Sat, Feb 23, 2008 at 1:05 AM, [EMAIL PROTECTED] wrote: Adding control effects (shift/reset) changes the expressivity results. Now all three calculi are distinct and none subsumes the other. For example, the expression reset( (\x - 1) (abort 2)) evaluates to 1 in call-by-name and evaluate to 2 in call-by-value. The expression reset ((\x - x + x) (shift f f)) has the type int-int in call-by-need (it is a function \x - x + x) and it has the type int-int-int in call-by-name (and it is the curried addition function). Aha. Okay, so shift/reset exposes evaluation order, amongst other things. Hm... thank you very much! -- Taral [EMAIL PROTECTED] Please let me know if there's any further trouble I can give you. -- Unknown ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Haskell w/ delimited continuations
On Sat, Feb 23, 2008 at 1:05 AM, [EMAIL PROTECTED] wrote: reset ((\x - x + x) (shift f f)) This one doesn't typecheck, since you can't unify the types (a - r) and r. -- Taral [EMAIL PROTECTED] Please let me know if there's any further trouble I can give you. -- Unknown ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] how to catch keyboard interrupts?
Hi, all, I am continuing to mess with my little scheme interpreter, and I decided that it would be nice to be able to hit control-C in the middle of a long-running scheme computation to interrupt that and return to the lisp prompt; hitting control-C and getting back to the shell prompt works, but is a little drastic. So I looked at System.Posix.Signals and after a bit of messing about got the following: mysighandler = Catch (do hPutStrLn stderr caught a signal! fail Interrupt!) runREPL :: IO () runREPL = do getProgName = writeHdr env - setupBindings [] True runInit env installHandler sigINT mysighandler Nothing installHandler sigQUIT mysighandler Nothing doREPL env This compiles just fine, the interpreter runs as usual... but the added code doesn't seem to do anything. You can probably guess already... the print statement in mysighandler is there to see if it actually caught a signal. It does: I see caught a signal! just fine, in fact I see dozens of them as I lean on the control-C; but now my scheme calculation doesn't get interrupted at all! I see in the System.Posix.Signals documentation that the signal handler gets invoked in a new thread; is this the source of the problem? If so, what should I do to fix it? I'm afraid that sort of stuff is still beyond my haskell-fu... many thanks! Uwe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Haskell Weekly News: February 23, 2008
--- Haskell Weekly News http://sequence.complete.org/hwn/20080223 Issue 70 - February 23, 2008 --- Welcome to issue 70 of HWN, a newsletter covering developments in the [1]Haskell community. One hundred unique new and updated libraries and applications in the past two weeks, including mutable arrays, compression, games, web frameworks, data structures, a file system, Haskell tools, concurrency, graphics, cryptography, systems administration, signal processing, new guis and several audio libraries 1. http://haskell.org/ Hackage New and updated libraries in [2]the Hackage library database. 2. http://hackage.haskell.org/ * ArrayRef 0.1.2. Uploaded by Gwern Branwen. [3]ArrayRef: Unboxed references, dynamic arrays and more. * zlib 0.4.0.4. Uploaded by Duncan Coutts. [4]zlib: Compression and decompression in the gzip and zlib formats. * hetris 0.1. Uploaded by Gwern Branwen. [5]hetris: Text Tetris. * bzlib 0.4.0.3. Uploaded by Duncan Coutts. [6]bzlib: Compression and decompression in the bzip2 format. * HAppS-Server 0.9.2. Uploaded by David Himmelstrup. [7]HAppS-Server: Web related tools and services.. * HAppS-State 0.9.2. Uploaded by David Himmelstrup. [8]HAppS-State: Event-based distributed state.. * HAppS-Data 0.9.2. Uploaded by David Himmelstrup. [9]HAppS-Data: HAppS data manipulation libraries. * HAppS-IxSet 0.9.2. Uploaded by David Himmelstrup. [10]HAppS-IxSet: Added by DavidHimmelstrup, Fri Feb 22 15:18:20 PST 2008.. * HAppS-Util 0.9.2. Uploaded by David Himmelstrup. [11]HAppS-Util: Web framework. * Ranged-sets 0.2.0. Uploaded by Paul Johnson. [12]Ranged-sets: Ranged sets for Haskell. 3. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/ArrayRef-0.1.2 4. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/zlib-0.4.0.4 5. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hetris-0.1 6. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/bzlib-0.4.0.3 7. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/HAppS-Server-0.9.2 8. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/HAppS-State-0.9.2 9. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/HAppS-Data-0.9.2 10. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/HAppS-IxSet-0.9.2 11. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/HAppS-Util-0.9.2 12. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/Ranged-sets-0.2.0 * halfs 0.2. Uploaded by Gwern Branwen. [13]halfs: Haskell File System. * sessions 2008.2.22. Uploaded by Matthew Sackman. [14]sessions: Session Types for Haskell. * infix 0.1. Uploaded by Gwern Branwen. [15]infix: Infix expression re-parsing (for HsParser library). * reify 0.1. Uploaded by Gwern Branwen. [16]reify: Serialize data. * highWaterMark 0.1. Uploaded by Gwern Branwen. [17]highWaterMark: Memory usage statistics. * hinvaders 0.1. Uploaded by Gwern Branwen. [18]hinvaders: Space Invaders. * baskell 0.1. Uploaded by Gwern Branwen. [19]baskell: An interpreter for a small functional language. * control-event 0.2. Uploaded by Thomas DuBuisson. [20]control-event: Event scheduling system.. * nymphaea 0.1. Uploaded by Gwern Branwen. [21]nymphaea: An interactive GUI for manipulating L-systems. * hopenssl 1.0. Uploaded by Peter Simons. [22]hopenssl: FFI bindings to OpenSSL's EVP digest interface. 13. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/halfs-0.2 14. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/sessions-2008.2.22 15. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/infix-0.1 16. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/reify-0.1 17. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/highWaterMark-0.1 18. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hinvaders-0.1 19. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/baskell-0.1 20. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/control-event-0.2 21. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/nymphaea-0.1 22. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hopenssl-1.0 * Monadius 0.91. Uploaded by Gwern Branwen. [23]Monadius: 2-D arcade scroller. * postmaster 0.1. Uploaded by Peter Simons. [24]postmaster: Postmaster ESMTP Server. * hsyslog 1.2. Uploaded by Peter Simons. [25]hsyslog: FFI interface to syslog(3) from POSIX.1-2001.. * hsemail 1.2. Uploaded by Peter Simons. [26]hsemail: Internet Message Parsers. * hsdns 1.3. Uploaded by Peter Simons
[Haskell-cafe] Re: fast graph algorithms without object identities
Henning Thielemann wrote: It seems that algorithms on graphs can be implemented particularly efficient in low-level languages with pointers and in-place updates. E.g. topological sort needs only linear time, provided that dereferencing pointers requires constant time. I could simulate pointer dereferencings and pointer updates by Map yielding linear logarithmic time for topological sort. I wonder if it is possible to write a linear time topological sort using lazy evaluation, since the runtime system of Haskell implementations is a graph processor based on pointers. First of all, topological sorting is only linear time because the 32 or 64 bit used to label nodes aren't counted. Put differently, random access in constant time to a collection of n elements doesn't exist. That being said, we want to use arrays of course. Preferably in a whole-meal way that doesn't involve incremental state updates. A few minutes ago, I stumbled upon the lazyarray packages which points to the paper Thomas Johnsson. Efficient Graph Algorithms Using Lazy Monolithic Arrays http://citeseer.ist.psu.edu/95126.html which offers such a way! (Although I currently don't quite understand why this works, and these ad-hoc unique numbers bother me.) Regards, apfelmus ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] A little toy of Haskell Trivia
On Sat, Feb 23, 2008 at 10:59:40AM -0500, Steve Lihn wrote: I parsed through all the hackagedb modules. I also added the display of repository source (ghc, hdb) and package source. HackageDB is 3-4 times bigger than GHC core. The result is interesting, looking at the most used modules move up and down the rank... http://haskell.ecoin.net/cgi-bin/modules.pl You'd get a different picture again if you excluded same-package imports. Some of the high-ranking modules are used internally in large packages. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Haskell w/ delimited continuations
Taral [EMAIL PROTECTED] wrote in article [EMAIL PROTECTED] in gmane.comp.lang.haskell.cafe: On Sat, Feb 23, 2008 at 1:05 AM, [EMAIL PROTECTED] wrote: reset ((\x - x + x) (shift f f)) This one doesn't typecheck, since you can't unify the types (a - r) and r. Some type systems for delimited continuations, such as Danvy and Filinski's (http://www.daimi.au.dk/~danvy/Papers/fatc.ps.gz; DIKU TR 89/12), allows changing the answer type and admits this code. -- Edit this signature at http://www.digitas.harvard.edu/cgi-bin/ken/sig God exists since mathematics is consistent, and the devil exists since its consistency cannot be proved. -- Hermann Weyl. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] haskellwiki and Project Euler
Hi all, I try not to be too rude, although I'm rather disgusted. I know there are several sites out on the web where solutions to PE problems are given. That is of course absolutely against the sporting spirit of Project Euler, but hey, not all people are sporting. I've found http://www.haskell.org/haskellwiki/Euler_problems irritating for a while, but wasn't overly annoyed by it while it only contained code for solving a few dozen problems. Today I learnt that it now contains code for all problems. Really bad! On top of that, the code for many problems isn't even Haskell, but C, WTF! Other code was submitted without consent of the author, copied from the PE fora, which are restricted access and so, even if perhaps not legally, but in spirit, do not fall under the legitimate resources for haskellwiki: You are also promising us that you wrote this yourself, or copied it from a public domain or similar free resource. DO NOT SUBMIT COPYRIGHTED WORK WITHOUT PERMISSION! To make matters worse still, there was a page containing nothing but the answers. That was changed, but Cale chose to reintroduce that crap. I just removed it again. Your turn, Cale. I call on the Haskell community to vote for immediate removal of these pages from the wiki! Show that you're a sporting bunch. Daniel Fischer ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] haskellwiki and Project Euler
Daniel Fischer wrote: Hi all, I try not to be too rude, although I'm rather disgusted. I know there are several sites out on the web where solutions to PE problems are given. That is of course absolutely against the sporting spirit of Project Euler, but hey, not all people are sporting. I've found http://www.haskell.org/haskellwiki/Euler_problems irritating for a while, but wasn't overly annoyed by it while it only contained code for solving a few dozen problems. Today I learnt that it now contains code for all problems. Really bad! On top of that, the code for many problems isn't even Haskell, but C, WTF! Other code was submitted without consent of the author, copied from the PE fora, which are restricted access and so, even if perhaps not legally, but in spirit, do not fall under the legitimate resources for haskellwiki: You are also promising us that you wrote this yourself, or copied it from a public domain or similar free resource. DO NOT SUBMIT COPYRIGHTED WORK WITHOUT PERMISSION! To make matters worse still, there was a page containing nothing but the answers. That was changed, but Cale chose to reintroduce that crap. I just removed it again. Your turn, Cale. I call on the Haskell community to vote for immediate removal of these pages from the wiki! Show that you're a sporting bunch. Daniel Fischer ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe You're going the right way about having the answers published in more ways than just the Haskell wiki. I'm only making a prediction, not a threat. -- Tony Morris http://tmorris.net/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] how to catch keyboard interrupts?
Hello Uwe, Saturday, February 23, 2008, 11:35:35 PM, you wrote: mysighandler = Catch (do hPutStrLn stderr caught a signal! fail Interrupt!) scheme calculation doesn't get interrupted at all! I see in the System.Posix.Signals documentation that the signal handler gets invoked in a new thread; is this the source of the problem? yes, fail kills only this thread :) you should store thread id of thread running interpreter and send async exception to it. control.concurrent is probably contains all required functions -- Best regards, Bulatmailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] how to catch keyboard interrupts?
Thanks, Bulat, I'll look into this! On 2/23/08, Bulat Ziganshin [EMAIL PROTECTED] wrote: Hello Uwe, Saturday, February 23, 2008, 11:35:35 PM, you wrote: mysighandler = Catch (do hPutStrLn stderr caught a signal! fail Interrupt!) scheme calculation doesn't get interrupted at all! I see in the System.Posix.Signals documentation that the signal handler gets invoked in a new thread; is this the source of the problem? yes, fail kills only this thread :) you should store thread id of thread running interpreter and send async exception to it. control.concurrent is probably contains all required functions -- Best regards, Bulatmailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] haskellwiki and Project Euler
You're going the right way about having the answers published in more ways than just the Haskell wiki. I'm only making a prediction, not a threat. Might be. And I've been over-angered. Having the Haskell code for the solutions in the wiki might be legitimate, but a) no code should be put there without the author's consent and b) posting C/C++ code there indicates that the reason for that is to be a spoil-sport, not to further learning/thinking Haskell. The latter even more applies to publishing the bare answers. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] how to catch keyboard interrupts?
On 2/23/08, Bulat Ziganshin [EMAIL PROTECTED] wrote: [about my question about keyboard interrupts] you should store thread id of thread running interpreter and send async exception to it. control.concurrent is probably contains all required functions Most splendid! Here's what I did data MyInterrupt = MyInt Int instance Typeable MyInterrupt where typeOf x = typeOf (0 :: Int) catcher :: MyInterrupt - IO () catcher e = hPutStrLn stderr interrupt! then later, in the REPL catchDyn (evalAndPrint env True line) (\e - catcher e) and in the initialization mysighandler tid = Catch (throwDynTo tid (MyInt 0)) and myTID - myThreadId installHandler sigINT (mysighandler myTID) Nothing installHandler sigQUIT (mysighandler myTID) Nothing doREPL env I had to add the MyInterrupt stuff because GHC was complaining about ambiguous types, initially I had just (\e - hPutStrLn stderr (show e)) as the second arg of the catchDyn. And try it in the self-test... Now test number/string conversions... this'll take a bit longer interrupt! lisp It works! Cool! This is worth bumping the version number :-) Many thanks! Uwe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] haskellwiki and Project Euler
Shame on you Haskell wiki! :) Perhaps it's a conpiracy to avoid wasting too much of the community effort on PE, and direct that energy to darcs :) - Quan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
