Re: [Haskell-cafe] Display an inferred type during compilation
On Sat, Apr 27, 2013 at 12:55 PM, Corentin Dupont corentin.dup...@gmail.com wrote: can I ask the compiler to display the type of an inferred value during compile time? It would be great if I can output a string during compilation with the type. A little bit like running :type in GHCi, but without GHCi... Because running GHCi is sometime painful (I have to clean my code first). You could try floating a value to the top level; then I believe -Wall will make ghc print out the inferred type since you didn't give a type signature. -- gwern http://www.gwern.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Resource Limits for Haskell
On Mon, Apr 1, 2013 at 5:56 PM, Edward Z. Yang ezy...@mit.edu wrote: http://ezyang.com/papers/ezyang13-rlimits.pdf Correct me if I'm wrong, but reading that I don't seem to see any tests against actual adversarial code - just checking that the limits kick in on a bunch of ordinary code. -- gwern http://www.gwern.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] mueval, interpreter options
On Tue, Apr 2, 2013 at 1:34 PM, Johannes Waldmann waldm...@imn.htwk-leipzig.de wrote: I don't understand mueval's design anyway here: do the interpreter options mean that these are automatically on, or just that the source text will be allowed to switch then on? (I'd prefer the latter.) I'm not clear on what you're doing there (I don't recognize your snippet), but extensions are enabled as options: -X EXTENSION --extension=EXTENSIONPass additional flags enabling extensions just like you would to ghc. Example: -XViewPatterns So for example: $ mueval -e let f (id - x) = x in f 1 -XViewPatterns 1 $ mueval -e let f (id - x) = x in f 1 -XMultiParamTypeClasses Illegal view pattern: id - x Use -XViewPatterns to enable view patterns -- gwern http://www.gwern.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Specialized Computer Architecture - A Question
On Mon, Mar 18, 2013 at 4:31 PM, OWP owpmail...@gmail.com wrote: If I may ask, I'm not quite sure what O(2^n) and O(1) are? Just a metaphor using algorithmic complexity, is all. I'm curious, were not all these built on the foundation of Moore's Law? Everything Vigoda lists has Moore's Law in mind. If Moore's Law were to suddenly disappear, could these survive on their own merit? No one really knows, since Moore's law has operated for so long. There seem to be constant factors to be had in my opinion* but in some problems/areas/domains, ASICs don't seem to help very much**, and we should not forget the colossal investments that a cutting-edge X86 chip fab represents*** which may make the best general bang for buck a commodity processor. For example, for every person who trumpets a 100x gain in switching their program to a GPU, there's another person abandoning their effort because they lose all the speed gains in transferring data back and forth from the GPU. But I think this is getting pretty off-topic for Haskell-cafe. * I'm not an expert, but some useful material is in http://www.gwern.net/Aria%27s%20past,%20present,%20and%20future#fn3 and http://www.gwern.net/Self-decrypting%20files#constant-factors ** the more serial a problem is, the more conditionals, memory accesses, and distinct operations a task requires, the more the optimal processor will... look like a CPU. *** http://www.gwern.net/Slowing%20Moore%27s%20Law#fab-costs-and-requirements -- gwern ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Specialized Computer Architecture - A Question
On Sun, Mar 17, 2013 at 5:56 PM, OWP owpmail...@gmail.com wrote: These stock architectures, were they really so good that they out performed the specialized ones on it's own merits or was this mainly due to Moore's Law on transistors? In other words, suppose we separate Moore's Law from the stock architecture, would it still outperform the specialized ones? It's not really meaningful to separate them. Any time you use a custom architecture, you are forfeiting all sorts of network effects - and sooner or later, the custom architecture falls behind. If you want to make an analogy, when you go with a custom architecture, you are trading a process where your computing power increases O(2^n) for one with a big constant factor but where computing power increases O(1)... In practice replacing digital computers with an alternative computing paradigm is a risky proposition. Alternative computing architectures, such as parallel digital computers have not tended to be commercially viable, because Moore's Law has consistently enabled conventional von Neumann architectures to render alternatives unnecessary. Besides Moore's Law, digital computing also benefits from mature tools and expertise for optimizing performance at all levels of the system: process technology, fundamental circuits, layout and algorithms. Many engineers are simultaneously working to improve every aspect of digital technology, while alternative technologies like analog computing do not have the same kind of industry juggernaut pushing them forward. from Benjamin Vigoda, Analog Logic: Continuous-Time Analog Circuits for Statistical Signal Processing (2003 PhD thesis) -- gwern http://www.gwern.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Resource Limits for Haskell
On Fri, Mar 15, 2013 at 5:17 PM, Edward Z. Yang ezy...@mit.edu wrote: There is a lot of subtlety in this space, largely derived from the complexity of interpreting GHC's current profiling information. Your questions, comments and suggestions are greatly appreciated! How secure is this? One of the reasons for forking a process and then killing it after a timeout in lambdabot/mueval is because a thread can apparently block the GC from running with a tight enough loop and the normal in-GHC method of killing threads doesn't work. Can one simultaneously in a thread allocate ever more memory and suppress kill signals? -- gwern http://www.gwern.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Maintaining lambdabot
On Wed, Feb 20, 2013 at 12:59 PM, Jan Stolarek jan.stola...@p.lodz.pl wrote: Exactly. This allows to use and develop these packages independently of lambdabot and I consider that a Good Thing. I'm also much in favor of using git, because github allows easy collaboration between community members. It may be a good thing, but speaking as the de facto maintainer of lambdabot for the past few years, it's a very small good thing and the goodness may be outweighed by the costs of switching: hardly anyone ever sends in patches for lambdabot proper, and even fewer for those add-on runtime dependencies. I am reminded of a recent incident on the XMonad mailing list: an enthusiastic young member proposed changing the entire infrastructure to Github because Github is the new hotness and it would surely promote easy collaboration between community members and so on and so forth. He put in a bunch of work in making copies and converting repos etc, and... nothing happened. His effort was wasted. Turns out the reason for people not submitting patches had more to do with things besides not being hosted on Github. -- gwern http://www.gwern.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Maintaining lambdabot
On Wed, Feb 20, 2013 at 1:35 PM, Jan Stolarek jan.stola...@p.lodz.pl wrote: Gwern, and what do you think about James' fork of lambdabot? It seems that there was a lot of work put into it and that this is indeed a good starting point to continue development. I haven't looked at the diffs; if as he says the security around the evaluation has been weakened, that's a deal-breaker until it's fixed. lambdabot can't be insecure since it will be run in a public IRC. -- gwern http://www.gwern.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Maintaining lambdabot
On Tue, Feb 19, 2013 at 5:36 PM, Jan Stolarek jan.stola...@p.lodz.pl wrote: - remove unlambda, brainfuck and show from the repo. They are on hackage, no need to keep them here - these packages aren't even used in the build process. Where will they go? -- gwern http://www.gwern.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] A list of Haskell-related quotes?
On Wed, Feb 6, 2013 at 5:36 PM, Petr Pudlák petr@gmail.com wrote: Does anybody collect them or know about such a collection? You can look at the Haskell Weekly News quote sections, or you can download the lambdabot source repo and read the State/quote file. -- gwern http://www.gwern.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Substantial (1:10??) system dependencies of runtime performance??
On Sat, Feb 2, 2013 at 3:19 PM, Nick Rudnick nick.rudn...@gmail.com wrote: Roughly, I would say the differences in runtime can reach a factor as much as 1:10 at many times -- and so I am curious whether this subject has already been observed or even better discussed elsewhere. I have spoken to somebody, and our only plausible conclusion was that software like web browsers is able to somewhat aggressively claim system resources higher in the privilege hierarchy (cache?? register??), so that they are not available to other programs any more. Maybe the Haskell program requires a lot of disk IO? That could easily lead to a big performance change since disk is so slow compared to everything else these days. You could try looking with 'lsof' to see if the browser has a ton of files open or try running the Haskell program with higher or lower disk IO priority via 'ionice'. -- gwern http://www.gwern.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Most used functions in hackage
One thing you could do is download Hackage (easy enough with a little scripting of 'cabal list'; see for example http://www.haskell.org/pipermail/haskell-cafe/2011-July/093669.html ), unpack, and use Language.Haskell.Exts to parse every Haskell file. Here are two examples from the past: 1. http://www.haskell.org/pipermail/haskell-cafe/2012-January/098618.html function-name search script which lets you parse a large number of source files and print out anything calling a specified function (eg. if you were thinking about deprecating something) 2. http://www.haskell.org/pipermail/haskell-cafe/2011-May/091663.html language-extension search script; I used it to see how many source files ever invoked LANGUAGE pragmas and which ones. -- gwern http://www.gwern.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Haskell Summers of Code retrospective (updated for 2012)
The Wheel turns, and months come and pass, leaving web links that fade into 403 Forbiddens; a wind rose in NYC, whispering of the coming Winter... As is now customary for me, I've looked into how the 2012 SoCs went - the better to feed my misanthropic heart by mocking the students who failed my whimsically arbitrary and subjective standards: http://www.gwern.net/Haskell%20Summer%20of%20Code#results-2 This was not a good year. 2 students simply dropped out period, and 3 other projects turned out badly, leaving just 2 clearly successful projects for the year. Hopefully 2013 will turn out better. /r/haskell: http://www.reddit.com/r/haskell/comments/15sjur/summer_of_code_2012_retrospective/ -- gwern ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] delete http://www.haskell.org/haskellwiki/Haskell_IDE
On Wed, Nov 28, 2012 at 3:24 PM, Roman Beslik rabes...@gmail.com wrote: A humble link What links here to the right will help you find those pages. Only for wikipages, nowhere else on the Internet. -- gwern http://www.gwern.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] size of Haskell Platform
On Sun, Nov 11, 2012 at 11:59 AM, Doug McIlroy d...@cs.dartmouth.edu wrote: So it seems to be with Haskell Platform, which aims to include all you need to get up and running--an extensive set of standard libraries and utilities with full documentation. I get the impression that the Platform is bedeviled by the same prospect of almost unfettered growth. That's an interesting story, but I think the analogy is fundamentally broken. So the pump needed someone to watch it, needed spares, needed multiple people for multiple shifts, then they needed mechanics and motor pools and all their families came along etc until finally it was a little town? Well, OK. But there's no such effect in software libraries - if I add in a bytestring library to the HP, I don't wind up needing a MS Excel shim library to service it! When I added in some popular core library like bytestring, there's no expansionary loop - I don't find myself needing to add in a dozen libraries just to make bytestring run better. Bytestring already runs fine. Its dependencies are all already in the HP; the additional complexity for adding Bytestring is just... Bytestring. The arrow of dependency points the other way than in your story - if I need a MS Excel shim library, maybe I'll need the bytestring library. It's a pyramid, not a repeatedly cycling positive feedback loop. (Incidentally, Geoffrey West's city research suggests that cities benefit from sublinear scaling of most infrastructure; so barely missing criticality is not at all surprising.) -- gwern http://www.gwern.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] [Off-topic] How unimportant it is whether submarines can swim (EWD1056)
On Fri, Oct 26, 2012 at 4:51 PM, Henk-Jan van Tuyl hjgt...@chello.nl wrote: L.S., I thought you might be interested to know, that I have translated one of prof. Edsger W. Dijkstra's writings to English[0]. I will submit this translation to the E. W. Dijkstra Archive of the University of Texas[1]. Comments: - with which popular believe (popular belief?) - between day and night (night and day is more idiomatic in English, isn't it?) - 'The advantage of this poetic license is that it allows us to put an algebraic expression as (a+b)/c, a program fragment as x := x+1, and a decimal number like 729 all three under the same heading formula.' (all three is weirdly run together with the list) - Our traditional argues (?) The hyphenation also strikes me as odd but I guess not actually wrong. -- gwern http://www.gwern.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Hackage Package Discoverability
On Tue, Oct 23, 2012 at 1:53 AM, Myles C. Maxfield myles.maxfi...@gmail.com wrote: Is there a better way to make this algorithm discoverable? How about deprecation pragmas? http://www.haskell.org/ghc/docs/7.2.2/html/users_guide/pragmas.html -- gwern http://www.gwern.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Getting PID of a child process
On Thu, Oct 18, 2012 at 5:03 PM, Jason Dusek jason.du...@gmail.com wrote: For diagnostic purposes, I'd like to print the PID of the process attached to this handle -- how best to do that? In Mueval when I wanted the PID (so I could later send sigkills), I did this: hdl - runProcess mueval-core args Nothing Nothing Nothing Nothing Nothing _ - forkIO $ do threadDelay (7 * 70) status - getProcessExitCode hdl case status of Nothing - do terminateProcess hdl _ - withProcessHandle hdl (\x - case x of OpenHandle pid - signalProcess 9 pid return (undefined, undefined) _ - return (undefined,undefined)) exitWith (ExitFailure 1) Just a - exitWith a stat - waitForProcess hdl exitWith stat The key is the poorly documented withProcessHandle :: System.Process.Internals.ProcessHandle - (ProcessHandle__ - IO (ProcessHandle__, a)) - IO a The implementation: data ProcessHandle__ = OpenHandle PHANDLE | ClosedHandle ExitCode type PHANDLE = CPid Well, my code seems to work, anyway... -- gwern http://www.gwern.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] How to take a minimum sub list that only contain certain number of elements of certain type?
On Tue, Sep 25, 2012 at 1:42 PM, Rishabh Jain rishab...@live.com wrote: f x 0 = [] f (x:xs) y | x `mod` 2 == 0 = x : (f xs y) | otherwise = x : (f xs (y-1)) f [0..] 4 [0,1,2,3,4,5,6,7] Tsk, tsk. So ugly. How's this: let f x = take x . filter odd f 4 [0..] ~ [1, 3, 5, 7] Notice that 0 is excluded, since 0 is *even*, not odd: http://en.wikipedia.org/wiki/Parity_of_zero If this is a serious problem, one can always just prepend zero: 0 : f 4 [1..] ~ [0, 1, 3, 5, 7] -- gwern http://www.gwern.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] How to take a minimum sub list that only contain certain number of elements of certain type?
On Tue, Sep 25, 2012 at 8:17 PM, Richard O'Keefe o...@cs.otago.ac.nz wrote: Wrong. The original poster gave an explicit example in which even elements were *retained* in the output, they just weren't *counted*. You are at least the fourth person to email me now to point this out. I'm glad I could make four people's day better with the joy of correction... But I never said it was a full solution - please note that I did include the output of the function! One could consider it a partial solution, however: that gives you the _nth_ odd, so if you want a list of numbers up to the _nth_ odd, that gives you a stop condition - 'takeWhile =/ nth+1' etc. A 2N traverse (which laziness might fuse to just 1 traverse, dunno). -- gwern http://www.gwern.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] How to take a minimum sub list that only contain certain number of elements of certain type?
On Tue, Sep 25, 2012 at 8:45 PM, Richard O'Keefe o...@cs.otago.ac.nz wrote: That doesn't work either. Consider the list [1,1,1,1,1]. The element just after the 5th odd number in the list is 1; takeWhile (/= 1) will thus return [] instead of [1,1,1,1]. I'm not sure that OP would prefer [1,1,1,1] to []. Another area of underspecification. -- gwern http://www.gwern.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Darcs fetches too little files
On Fri, Aug 24, 2012 at 4:47 PM, Henk-Jan van Tuyl hjgt...@chello.nl wrote: I am trying to fetch wxHaskell with the command darcs get --lazy http://code.haskell.org/wxhaskell/ but there are much too little files downloaded; what could be the problem? I'm working on Windows XP, both in an MS-DOS shell and an MSYS shell. Installed Darcs version: 2.8.1 Could you be more specific? The point of --lazy *is* to fetch very few files, so as described, it's working as it should... -- gwern http://www.gwern.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] [Haskell] Spam on the Haskell wiki
On Fri, Aug 3, 2012 at 10:34 PM, damodar kulkarni kdamodar2...@gmail.com wrote: So, another doubt, if detecting spam is trivial, then why not just send the detected spam to trash directly without any human inspection? This may mean some trouble for the posters due to false positives; but the moderator's job can be reduced to some extent. Which is pretty much what this whole thread is about: asking that the sysadmins Do Something about this trivial yet overwhelming spam. -- gwern http://www.gwern.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] [Haskell] Spam on the Haskell wiki
On Mon, Jul 30, 2012 at 6:59 PM, Alexander Solla alex.so...@gmail.com wrote: We could even have a report spam button on each page, and if enough users click on it (for a given revision), the revision gets forwarded to a moderator. This would be useless. The problem is not detecting spam, since that's quite trivial: it's very hard to miss. The problem is that the moderator (ie. me) is already overworked. The spam needs to be reduced to begin with, not detected. -- gwern http://www.gwern.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] lambdabot-4.2.3.3
On Wed, Jul 18, 2012 at 11:12 AM, James Cook mo...@deepbondi.net wrote: It diverged from the official version quite a while ago, but it builds on the latest GHC and uses Safe Haskell for the @eval module. That doesn't sound very safe. How does it handle all the DoS attacks etc in the mueval test suite? -- gwern http://www.gwern.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell] Spam on the Haskell wiki
I recently moved, and when I returned to the Internet a few days later, I was greeted with several hundred spam pages in Recent Changes. The torrent of spam has not let up, and I estimate that I have blocked 3-500 accounts and deleted as many pages. (I blocked another 5 or so while composing this email.) Certainly the deletion and block logs are long enough: - http://www.haskell.org/haskellwiki/index.php?title=Special%3ALogtype=deleteuser=page= - http://www.haskell.org/haskellwiki/index.php?title=Special:Ipblocklistlimit=500 I have asked Ashley Yakeley to turn on additional anti-spam measures, but he has not been active on the wiki since January (http://www.haskell.org/haskellwiki/Special:Contributions/Ashley_Y http://www.haskell.org/haskellwiki/index.php?title=Special:Loguser=Ashley_Y), and has not replied to my talk messages or accompanying emails. I had to do this single-handedly as there are no other administrators. This took up a good chunk of today and yesterday, and the spam is continuing. I cannot handle it much longer: it's incredibly tedious and using up far more time than I have to give it. Measures need to be taken: 1. Email confirmation needs to be checked that Ashley did in fact enable it. I suspect he did not, since I also administrate the LessWrong wiki - which I know for certain has email confirmation is enabled - is being attacked by the same spammers (similar or identical templates spam) but at a much reduced scale. 2. Additional administrators must be created. I suggest: - dons - Magnus Therning - Neil Mitchell - byorgey - Henk-Jan van Tuyl I am sure there are others who can be trusted. 3. Additional bureaucrats should be created. I suggest myself. 4. ReCAPTCHA enabled for 'edits adding new, unrecognized external links' - which is all of the spam. Further reading: http://www.mediawiki.org/wiki/Manual:Combating_spam http://www.mediawiki.org/wiki/Anti-spam_features 5. if Ashley is inactive, his account may be a security risk. The English Wikipedia now removes administrator bits after a year of inactivity; we should consider a similar policy. None of these can be taken by myself, as I am neither a sysadmin on Haskell.org nor a bureaucrat on the wiki. If none of these steps are taken and spam continues to remain a problem in 2 months (15 September 2012), I will cease patrolling Recent Changes. I no longer have the time or patience. -- gwern http://www.gwern.net ___ Haskell mailing list Haskell@haskell.org http://www.haskell.org/mailman/listinfo/haskell
Re: [Haskell-cafe] Finding longest common prefixes in a list
On Sat, Jan 21, 2012 at 8:18 AM, Twan van Laarhoven twa...@gmail.com wrote:
Notice that there are lots of miku-X prefixes found. This is probably not
what you want. What exactly do you want the algorithm to do? For example,
is obviously a prefix of every string, but it is not very long. On the other
hand, each string is a prefix of itself, but that prefix is shared by only
one string (usually).
By the way, the sort and compare adjacent pairs approach corresponds to
atLeastThisManyDescendants 2.
Ah, now the code makes sense to me. It's longer, but it is a heck of a
lot more principled and readable, so I'm happy to replace my version
with yours. It's not too hard to convert it into a CLI filter with
optional depth (default of 2, replicating original behavior):
import qualified Data.Map as Map
import System.Environment (getArgs)
import Data.List (sortBy)
import Data.Ord (comparing)
main :: IO ()
main = do arg - getArgs
let n = if null arg then 2 else read (head arg) :: Int
interact (unlines . chunk n . lines)
chunk :: Int - [String] - [String]
chunk n = map prefix . sortByLength . atLeastThisManyDescendants n . fromList
where sortByLength :: [CommonPrefix Char] - [CommonPrefix Char]
sortByLength = sortBy (comparing (numDescendant . names))
.
And the results seem kosher (printing just the prefixes is probably
the best idea, but wouldn't be too hard to switch to printing full
filenames - just filter the original file list with the extracted
prefix from each CommonPrefix):
$ ls music/vocaloid/| runhaskell lcp.hs 5
miku-s
miku-t
miku-r
rin-
miku-a
gumi-
luka-
$ ls music/vocaloid/| runhaskell lcp.hs 4
miku-h
miku-m
miku-n
miku-p
miku-s
miku-t
miku-r
rin-
miku-a
gumi-
luka-
$ ls music/vocaloid/| runhaskell lcp.hs # with 2
chorus-
gumi-mo
gumi-s
kaito-
luka-emon
luka-t
miku-acolorlinkingworld-
miku-akayaka
miku-cleantears-remind2011natsu-
miku-dan
miku-ele
miku-galaxyodyssey-
miku-ha
miku-inn
miku-jemappelle-motion-
miku-kz-
miku-lo
miku-m@rk-
miku-plustellia-壁の彩度-
miku-ro
miku-se
miku-ta
miku-the
miku-tinyparadise-
miku-ジラートP-birthdayofeden-
miku-杯本選
miku-般若心経
niconicochorus-
yuki-
len-
luka-di
miku-re:package-
miku-n
rin-
--
gwern
http://www.gwern.net
import qualified Data.Map as Map
import System.Environment (getArgs)
import Data.List (sortBy)
import Data.Ord (comparing)
main :: IO ()
main = do arg - getArgs
let n = if null arg then 2 else read (head arg) :: Int
interact (unlines . chunk n . lines)
chunk :: Int - [String] - [String]
chunk n = map prefix . sortByLength . atLeastThisManyDescendants n . fromList
where sortByLength :: [CommonPrefix Char] - [CommonPrefix Char]
sortByLength = sortBy (comparing (numDescendant . names))
-- A trie datatype
data Trie a = Trie { numLeafs, numDescendant :: !Int
, children :: Map.Map a (Trie a) }
instance (Show a) = Show (Trie a) where
showsPrec _ t = showString fromList . shows (toList t)
-- The empty trie
empty :: Trie a
empty = Trie 0 0 Map.empty
-- A trie that contains a single string
singleton :: Ord a = [a] - Trie a
singleton [] = Trie 1 1 Map.empty
singleton (x:xs) = Trie 0 1 (Map.singleton x (singleton xs))
-- Merge two tries
merge :: Ord a = Trie a - Trie a - Trie a
merge (Trie l d c) (Trie l' d' c')
= Trie (l+l') (d+d') (Map.unionWith merge c c')
fromList :: Ord a = [[a]] - Trie a
fromList = foldr (merge . singleton) empty
toList :: Trie a - [[a]]
toList (Trie l _ c)
= replicate l []
++ [ x:xs | (x,t) - Map.toList c, xs - toList t ]
data CommonPrefix a = Prefix { prefix :: [a], names :: Trie a }
instance (Show a) = Show (CommonPrefix a) where
showsPrec _ (Prefix p ns) = shows p . showString ++ . shows (toList ns)
-- Find prefixes that have at least minD descendants.
-- when there is a prefix xs with =minD descendants, then shorter prefixes will not be returned
atLeastThisManyDescendants :: Int - Trie a - [CommonPrefix a]
atLeastThisManyDescendants minD trie@(Trie _ d c)
| d minD = [] -- too few descendants
| null forChildren = [Prefix [] trie] -- all longer prefixes have too few descendants, but this prefix doesn't
| otherwise = forChildren -- there are longer prefixes with enough descendants, return them
where
forChildren = [ Prefix (x:pfx) nms
| (x,t) - Map.toList c
, Prefix pfx nms - atLeastThisManyDescendants minD t ]
{- *Main mapM_ (print . prefix) $ atLeastThisManyDescendants 4 test1
gumi-
luka-
miku-a
miku-h
miku-m
miku-n
miku-p
miku-r
miku-s
miku-t
rin-
test1 :: Trie Char
test1 = fromList
[chorus-kiminoshiranaimonogatari.ogg
,chorus-mrmusic.ogg
,choucho-lastnightgoodnight.ogg
,dylanislame-aikotoba.ogg
,electriclove-エレクトリック・ラブ-korskremix.ogg
,gumi-bacon8-justhangingaround.ogg
,gumi-iapologizetoyou.ogg
,gumi-montblanc.ogg
,gumi-mozaikrole.ogg
,gumi-ハッピーシンセサイザ.ogg
[Haskell-cafe] Finding longest common prefixes in a list
Recently I wanted to sort through a large folder of varied files and
figure out what is a 'natural' folder to split out, where natural
means something like 4 files with the same prefix. (This might be
author, genre, subject, whatever I felt was important when I was
naming the file.) Now usually I name files with hyphens as the
delimiters like the hypothetical '1998-wadler-monads.pdf', and it
would be easy to write a stdin/stdout filter to break Strings on
hyphens and sort by whatever is most common. But this is rather
hardwired, can I solve the more general problem of finding the longest
common prefixes, whatever they are?
This turns out to be much more difficult than simply finding 'the'
longest common prefix (which is usually ). I found an algorithm of
sorts at http://stackoverflow.com/a/6634624 but it was easier
described than implemented. Eventually I wrote what I *think* is a
correct program, but it's definitely of the write-only sort. Perhaps
people have better implementations somewhere? I saw a lot of
discussion of tries, but I didn't go that route.
The code, followed by an example:
#!/usr/bin/env runhaskell
import Data.List (intercalate, isPrefixOf, nub, sort)
main :: IO ()
main = interact (unlines . intercalate [] . chunkFiles . lines )
-- basic algorithm from http://stackoverflow.com/a/6634624
chunkFiles :: Ord a = [[a]] - [[[a]]]
chunkFiles f = map (\(_,b) - filter (isPrefixOf b) f) $ sort $
map (\x - (countPrefixes x f,x)) (e $ bar f)
sharedPrefixes :: Ord a = [[a]] - [a]
sharedPrefixes [] = []
sharedPrefixes s = foldr1 sp2 s
where sp2 l1 l2 = map fst . takeWhile (uncurry (==)) $ zip l1 l2
traverse :: Ord a = [[a]] - [[a]]
traverse [] = []
traverse x = sharedPrefixes (take 2 x) : traverse (drop 1 x)
bar :: Ord a = [[a]] - [[a]]
bar = nub . sort . traverse . sort
countPrefixes :: (Ord a) = [a] - [[a]] - Int
countPrefixes x xs = length $ filter (x `isPrefixOf`) xs
e :: Eq a = [[a]] - [[a]]
e y = map fst $ filter snd $ map (\x - (x, (==) 1 $ length . filter
id $ map (x `isPrefixOf`) y)) y
{- Example input from `ls`:
chorus-kiminoshiranaimonogatari.ogg
chorus-mrmusic.ogg
choucho-lastnightgoodnight.ogg
dylanislame-aikotoba.ogg
electriclove-エレクトリック・ラブ-korskremix.ogg
gumi-bacon8-justhangingaround.ogg
gumi-iapologizetoyou.ogg
gumi-montblanc.ogg
gumi-mozaikrole.ogg
gumi-ハッピーシンセサイザ.ogg
gumi-showasengirl.ogg
gumi-sweetfloatflatsスイートフロートアパート.ogg
gumi-timewarpedafterchoppingmystagbeetle.ogg
gumi-オリジナル曲-付きホシメグリ.ogg
gumi-ミクオリジナル親友.ogg
kaito-byakkoyano.ogg
kaito-flowertail.ogg
kasaneteto-tam-ochamekinou重音テト吹っ切れたおちゃめ機能.ogg
len-crime-timetosaygoodbye.ogg
len-fire◎flower.ogg
len-ponponpon.ogg
lily-prototype.ogg
luka-apolxcore-waitingforyou.ogg
luka-dimトロイ.ogg
luka-dion-myheartwillgoon.ogg
luka-dirgefilozofio-dirgeasleepinjesus.ogg
luka-アゴアニキ-doubelariatダブルラリアット.ogg
luka-emon-heartbeats.ogg
luka-emonloid3-ハローハロー.ogg
luka-everybreathyoutake.ogg
luka-オリジナル-garden.ogg
luka-justbefriends.ogg
lukameiko-gemini.ogg
luka-milkyway.ogg
luka-やみくろ-かいぎ.ogg
luka-tic-tick.ogg
luka-torinouta.ogg
luka-zeijakukei-shounenshoujo.ogg
luka-勝手にアニメ-nologic-作ってみた.ogg
luka-駄目人間.ogg
meiko-artemis-awake.ogg
miku-9ronicleプラチナ.ogg
miku-acolorlinkingworld-この世界の下で.ogg
miku-acolorlinkingworld-青い花.ogg
miku-a+jugos-lullabyforkindness.ogg
miku-akayaka-beacon.ogg
miku-akayakap-sunrise.ogg
miku-aoihana.ogg
miku-arabianresponse.ogg
miku-avtechno-tear.ogg
miku-こえをきかせてcicci.ogg
miku-cleantears-remind2011natsu-greenhillzonecrystiararemix.ogg
miku-cleantears-remind2011natsu-夏影summerwindremix.ogg
miku-clocklockworks.ogg
miku-dancedancevol2-runner.ogg
miku-daniwellp-chaoticuniverse.ogg
miku-dixieflatline-shinonomescrumble.ogg
miku-electricloveエレクトリックラヴ.ogg
miku-elegumitokyo-kissmebaby.ogg
miku-galaxyodyssey-cryingirl.ogg
miku-galaxyodyssey-galaxyspacelines.ogg
miku-hakamairi.ogg
miku-haruna.ogg
miku-heartshooter.ogg
miku-hoshikuzutokakera.ogg
miku-innes.ogg
miku-innocence初音ミク.ogg
miku-jemappelle-motion-likeyou.ogg
miku-jemappelle-motion-ohwell.ogg
miku-jevannip-myfavoritesummer.ogg
miku-kakokyuudance-過呼吸ダンス.ogg
miku-kz-packaged.ogg
miku-kz-tellyourworld.ogg
miku-lastscene.ogg
miku-lostmemories付き-初音ミク.ogg
miku-lovelyday.ogg
miku-いいわけlove_song.ogg
mikulukagumi-prayfor.ogg
miku-maple-初音ミク楓-オリジナル曲.ogg
miku-more1.5.ogg
mik...@rk-eklosion.ogg
mik...@rk-kirch.ogg
miku-nana-ボーナストラック-ハッピー般若コア.ogg
miku-nekomimiswitch.ogg
miku-nightrainbow.ogg
miku-noyounome.ogg
miku-むかしむかしのきょうのぼくオリジナル.ogg
miku-pandolistp-neverendinghammertime.ogg
miku-ジラートP-birthdayofeden-deepsleep.ogg
miku-ジラートP-birthdayofeden-水中読書.ogg
miku-plustellia-dear.ogg
miku-plustellia-壁の彩度-crazygirl.ogg
miku-plustellia-壁の彩度-discoradio.ogg
miku-ぽわぽわP-ストロボライト.ogg
miku-rabbitforgets.ogg
miku-re:package-lastnightgoodnight.ogg
miku-re:package-ourmusic.ogg
miku-re:package-sutorobonaitsu.ogg
miku-rollinggirl.ogg
miku-ryo-メルト-melt.ogg
miku-senseiniitteyaro.ogg
miku-sevencolors-レモネード.ogg
miku-shoukinosatadenia.ogg
miku-stratosphere.ogg
miku-supernova.ogg
Re: [Haskell-cafe] Finding longest common prefixes in a list
On Fri, Jan 20, 2012 at 1:57 PM, Twan van Laarhoven twa...@gmail.com wrote: Here is some example code (untested): Well, you're right that it doesn't work. I tried to fix the crucial function, 'atLeastThisManyDescendants', but it's missing something because varying parts doesn't much affect the results when I try it out on example input - it either returns everything or nothing, it seems: atLeastThisManyDescendants :: Int - Trie a - [CommonPrefix a] atLeastThisManyDescendants minD trie@(Trie l d t') | d minD = [] | null forChildren = [Prefix [] trie] | otherwise = forChildren where forChildren = [ Prefix (x:pfx) nms | (x,t) - Map.toList t' , Prefix pfx nms - atLeastThisManyDescendants l t ] -- gwern http://www.gwern.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Pattern-matching substitution for haskell-src-exts?
On Wed, Jan 18, 2012 at 3:05 PM, Conal Elliott co...@conal.net wrote:
Has anyone implemented pattern-matching substitution for
haskell-src-exts? - Conal
I don't know what exactly you are looking for, but I remember banging
together a function-name search script using haskell-src-exts and
'find' last summer, which pattern-matches, looking for use of
particular function-names. Presumably you could change
`functionSearch` to not call `length` but instead replace the matched
function with another function and then write out the modules? Well,
maybe the source will be helpful, maybe not:
import System.Environment (getArgs)
import Language.Haskell.Exts
import qualified Data.Foldable as F (concat)
import Data.Generics.Uniplate.Data
-- import Debug.Trace
main :: IO ()
main = do (func:_) - getArgs
args - fmap lines $ getContents
mapM_ (checkAndPrint func) args
checkAndPrint :: String - FilePath - IO ()
checkAndPrint fn fs = do print fs
x - readFile fs
let exts = F.concat $ readExtensions x
let parsed = parseFileContentsWithMode
(defaultParseMode { fixities = fixes, extensions = exts }) x
case parsed of
ParseFailed _ _ - (return ())
ParseOk a - functionSearch fn a
return ()
-- the default fixities augmented with everything necessary to parse my corpus
fixes :: Maybe [Fixity]
fixes = Just $ baseFixities ++ infixr_ 0 [==]
functionSearch :: String - Module - IO ()
functionSearch fun md = do
let x = length [ () | Var (UnQual (Ident a)) - universeBi md, a == fun]
putStrLn $ Found ++ show x ++ occurences of function ++ fun
--
gwern
http://www.gwern.net
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[Haskell-cafe] Haskell Summers of Code retrospective (updated for 2011)
The Wheel turns, and months come and pass, leaving blog posts that fade into 404s; a wind rose in Mountain View, whispering of the coming Winter... Tonight I sat down and finally looked into the 2011 SoCs to see how they turned out and judge them according to my whimsically arbitrary and subjective standards: http://www.gwern.net/Haskell%20Summer%20of%20Code#results-1 They turned out pretty much as I predicted - but then I *would* say that, wouldn't I? (Also submitted to /r/haskell for those who swing that way: http://www.reddit.com/r/haskell/comments/n82ln/summer_of_code_2011_retrospective/ ) -- gwern http://www.gwern.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Google Knol and haskellers
On Thu, Oct 13, 2011 at 11:52 AM, Sean Leather leat...@cs.uu.nl wrote: On Wed, Oct 12, 2011 at 12:35, Yves Parès wrote: I re-head recently about Google Knol, which is IMO some crossing-over between a wiki and a blog. Are there some people that use it here to write haskell-related articles instead of a regular blog? As far as anybody outside Google knows, Knol has pretty much been abandoned. See http://googlesystem.blogspot.com/2011/01/abandoned-knol.html . I don't think it's worth contributing knowledge to it. I agree; I predicted back in January 2009 that it would fail to go anywhere, and checking up on it, I find that none of the stats have improved since then: http://www.gwern.net/Wikipedia%20and%20Knol#knol-did-fail Indeed, the real question for me is when it will officially die: http://www.gwern.net/Wikipedia%20and%20Knol#knol-death-watch Knol has zero advantages over the Haskell wiki, and never has, unless you want fanatical control of your content and miniscule ad content, in which case you are better off with your own blog. -- gwern http://www.gwern.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Solving the configuration problem with parametrized modules
On Mon, Sep 5, 2011 at 1:43 PM, Joachim Breitner m...@joachim-breitner.de wrote: Do you think this could be useful (from a user point of view)? Has this idea maybe already been proposed? How does it compare with Oleg's typeclass approach? http://okmij.org/ftp/Haskell/types.html#Prepose -- gwern http://www.gwern.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Truly Really Off-topic: (Was: Mathematics)
On Mon, Aug 29, 2011 at 11:19 AM, Jerzy Karczmarczuk jerzy.karczmarc...@unicaen.fr wrote: It is unsourced, repeated without discernment, and Dijkstra cannot confirm (or deny) it any more. Somehow I cannot believe he said that... Dijkstra began to study physics, and a physicist would be reluctant to make such puns. Why? Some googling takes me to the full quote: Computer science is no more about computers than astronomy is about telescopes, biology is about microscopes, or chemistry is about beakers and test tubes. Science is not about tools. It is about how we use them, and what we find out when we do. Which is referenced to, inside _Invitation to Computer Science_ (G. Michael Schneider, Judith L. Gersting, Keith Miller; http://books.google.com/books?id=gQK0pJONyhgC ), to Fellows, M.R., and Parberry, I. Getting Children Excited About Computer Science, _Computing Research News_, vol. 5, no. 1 (January 1993). Curiously, the preface to the quote is: This distinction between computers and computer science is beautifully expressed by computer scientists Michael R. Fellows and Ian Parberry in an article in the journal _Computing Research News_: *No* mention of Dijkstra. Searching that full book, the only Dijkstra mentions are unconnected to the quote. Chasing links, I head to http://archive.cra.org/CRN/issues/by_title_by_issue.html and download January 1993: http://archive.cra.org/CRN/issues/9301.pdf On page 7, I find it. The article title is different: SIGACT trying to get children excited about CS. The money line is highlighted. The relevant paragraph and surrounding paragraphs: Is it any wonder then that computer science is represented in many schools by either computer games or some antiquated approach to programming, which at worst concentrates on a litany of syntax and at best emphasizes expediency over effectiveness and efficiency? But computer science is not about computers—it is about computation. What would we like our children- the general public of the future—to learn about computer science in schools? We need to do away with the myth that computer science is about computers. Computer science is no more about computers than astronomy is about telescopes, biology is about microscopes or chemistry is about beakers and test tubes. Science is not about tools, it is about how we use them and what we find out when we do. It may come as a surprise to some that computer science is full of activities that children still find exciting even without the use of computers. Take theoretical computer science, for example, which may seem an unlikely candidate. If computer science is underrepresented in schools, then theoretical computer science is doubly so. This is the precise quote, with no quotation marks or references or allusions of any kind; this seems to be the original, where the exact quote comes from. There are no mentions whatsoever of Dijkstra in the January PDF. On Mon, Aug 29, 2011 at 11:25 AM, Christopher Done chrisd...@googlemail.com wrote: Wherever its origin, it is featured in SICP which was out in 1984: http://www.youtube.com/watch?v=zQLUPjefuWA It's a sound analogy. Abelson doesn't cite Dijkstra in the first minute where he makes the comparisons, either, unless I missed it. As well, in no Google hit did I find any specific citation to Dijkstra. Hence, I conclude that because it is insightful and sounds like Dijkstra (eg. his submarine quote), it has become apocryphally associated with him but is *not* actually a Dijkstra quote. -- gwern http://www.gwern.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Truly Really Off-topic: (Was: Mathematics)
On Mon, Aug 29, 2011 at 12:18 PM, aditya siram aditya.si...@gmail.com wrote: I'm afraid you're going to have a lot of OCD's completely miss the point of your email and annoy you with comments about the quote which you'll then have to refute. I dunno, I found the quote interesting. I had typed up a scornful response to the effect that everyone knows it's a Dijkstra quote and he could find sourcing in seconds with Google, but as the seconds passed, I had to rewrite the seconds bit, then as I found actual cites, I had to rewrite the Dijkstra bit, and then I realized that replying to that email might take a while... -- gwern http://www.gwern.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Truly Really Off-topic: (Was: Mathematics)
On Mon, Aug 29, 2011 at 11:47 AM, Gwern Branwen gwe...@gmail.com wrote: As well, in no Google hit did I find any specific citation to Dijkstra. Hence, I conclude that because it is insightful and sounds like Dijkstra (eg. his submarine quote), it has become apocryphally associated with him but is *not* actually a Dijkstra quote. To follow up: - 'telescopes' does not appear anywhere in the EWDs: http://ewd.cs.utexas.edu.master.com/texis/master/search/?sufs=0q=telescopesxsubmit=Searchs=SS - Ruud Koot points to an August* 1993 PhD thesis (http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.53.8045rep=rep1type=pdf) which attributes it, with no citation or sourcing information, to Dijkstra - a Redditor claims, with no citation or sourcing information, that it was Marvin Minsky (http://www.reddit.com/r/programming/comments/jy1zw/psa_dijkstra_did_not_say_computer_science_is_no/c2g17xt) * that is, well after the original January 1993 article -- gwern http://www.gwern.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Parsing cabal files to calculate average number of dependencies
On Fri, Jul 1, 2011 at 5:37 PM, Gwern Branwen gwe...@gmail.com wrote: Looking at it, the index tarball contains the .cabal files for all versions known to Hackage, which isn't necessarily the interesting set of cabal files - I'm usually more interested in just the cabal files of the latest version of every package. No doubt there's a scripting solution (loop over the untarred directory of packages, and take the lexically last cabal file?), but it was easier to just exploit cabal fetch's behavior of fetching only the latest version and work with those tarballs. The version using just the index tarball is kind of ugly; the filtering and extracting doesn't seem terribly easy, so the best script I could come up with was: cd ~/.cabal/packages/hackage.haskell.org for DIR in */; do (for CABAL in `tar --wildcards $DIR -tf 00-index.tar|head -1`; do (tar -Oxf 00-index.tar $CABAL | runhaskell ~/deps.hs); done); done (Parentheses aren't necessary but make it more readable.) -- gwern http://www.gwern.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Parsing cabal files to calculate average number of dependencies
Athas on #haskell wondered how many dependencies the average Haskell
package had. I commented that it seemed like some fairly simple
scripting to find out, and as these things tend to go, I wound up
doing a complete solution myself.
First, we get most/all of Hackage locally to examine, as tarballs:
for package in `cabal list | grep '\*' | tr -d '\*'`; do cabal
fetch $package; done
Then we cd .cabal/packages/hackage.haskell.org
Now we can run a command which extracts the .cabal file from each
tarball to standard output:
find . -name *.tar.gz -exec tar --wildcards *.cabal -Oxf {} \;
We could grep for 'build-depends' or something, but that gives
unreliable dirty results. (80k items, resulting in a hard to believe
87k total deps and an average of 27 deps.) So instead, we use the
Cabal library and write a program to parse Cabal files spit out the
dependencies, and we feed each .cabal into that:
find . -name *.tar.gz -exec sh -c 'tar --wildcards *.cabal
-Oxf {} | runhaskell ~/deps.hs' \;
And what is deps.hs? Turns out to be surprisingly easy to parse a
String, extract the Library and Executable AST, and grab the
[Dependency] field, and then print it out (code is not particularly
clean):
import Distribution.Package
import Distribution.PackageDescription
import Distribution.PackageDescription.Parse
main :: IO ()
main = do cbl - getContents
let desc = parsePackageDescription cbl
case desc of
ParseFailed _ - return ()
ParseOk _ d - putStr $ unlines $ map show $ map
(\(Dependency x _) - x) $ extractDeps d
extractDeps :: GenericPackageDescription - [Dependency]
extractDeps d = ldeps ++ edeps
where ldeps = case (condLibrary d) of
Nothing - []
Just c - condTreeConstraints c
edeps = concat $ map (condTreeConstraints . snd) $ condExecutables d
So what are the results? (The output of one run is attached.) I get
18,134 dependencies, having run on 3,137 files, or 5.8 dependencies
per package.
--
gwern
http://www.gwern.net
deps.txt.gz
Description: GNU Zip compressed data
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Re: [Haskell-cafe] Parsing cabal files to calculate average number of dependencies
On Fri, Jul 1, 2011 at 4:49 PM, L Corbijn aspergesoe...@gmail.com wrote: Is this including or exluding 'or'-ed dependency lists like http://hackage.haskell.org/package/hugs2yc ? Excluding, it seems. When I run the script on that tarball: $ tar --wildcards *.cabal -Oxf `find . -name *.tar.gz | g hugs2yc` | runhaskell /home/gwern/deps.hs PackageName mtl PackageName uniplate PackageName yhccore PackageName ycextra PackageName parsec PackageName directory PackageName filepath No version of base or containers appears. (mtl appears in both branches and also the general build-depends list.) -- gwern http://www.gwern.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Parsing cabal files to calculate average number of dependencies
On Fri, Jul 1, 2011 at 5:23 PM, Rogan Creswick cresw...@gmail.com wrote: I think the index tarball has all the info you need, and would be faster to retrieve / process, if you or anyone else needs to get the .cabal files again: http://hackage.haskell.org/packages/archive/00-index.tar.gz (2.2mb) Looking at it, the index tarball contains the .cabal files for all versions known to Hackage, which isn't necessarily the interesting set of cabal files - I'm usually more interested in just the cabal files of the latest version of every package. No doubt there's a scripting solution (loop over the untarred directory of packages, and take the lexically last cabal file?), but it was easier to just exploit cabal fetch's behavior of fetching only the latest version and work with those tarballs. -- gwern http://www.gwern.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Parsing cabal files to calculate average number of dependencies
Another thing you can do along the same lines is generate a script to download all the repos from packages which declare repos. Some ugly code: import Data.Maybe (fromJust) import Distribution.PackageDescription import Distribution.PackageDescription.Parse import Control.Monad (unless) main :: IO () main = do cbl - getContents let desc = parsePackageDescription cbl case desc of ParseFailed _ - return () ParseOk _ d - do let repos = repoPair $ extractHead $ extractRepos d let cmd = concatMap shellify repos unless (null cmd) $ putStrLn cmd shellify :: (RepoType, String) - String shellify (rt,url) = case rt of Darcs - darcs get ++ url Git - git clone ++ url SVN - svn clone ++ url CVS - cvs co ++ url Mercurial - hg clone ++ url _ - repoPair :: [SourceRepo] - [(RepoType, String)] repoPair = map (\x - (fromJust $ repoType x, fromJust $ repoLocation x)) extractHead :: [SourceRepo] - [SourceRepo] extractHead rs = filter (\x - isnothing x ishead x) rs where ishead sr = case repoKind sr of RepoHead - True _ - False isnothing ss = case repoType ss of Nothing - False Just _ - case repoLocation ss of Nothing - False Just _ - True extractRepos :: GenericPackageDescription - [SourceRepo] extractRepos = sourceRepos . packageDescription This generates results (with the same find command and setup as previously) like: ... git clone git://gitorious.org/maximus/mandulia.git darcs get http://darcs.cielonegro.org/HsOpenSSL/ darcs get http://darcs.cielonegro.org/HsOpenSSL/ hg clone https://bitbucket.org/bos/text-icugit clone https://github.com/bos/text-icu darcs get http://code.haskell.org/Graphalyze darcs get http://code.haskell.org/~roelvandijk/code/base-unicode-symbols git clone git://github.com/roelvandijk/base-unicode-symbols.git darcs get http://code.haskell.org/~basvandijk/code/regions git clone https://github.com/skogsbaer/xmlgen git clone git://github.com/tanakh/HongoDB.git darcs get http://repos.mornfall.net/shellish darcs get http://patch-tag.com/r/Saizan/syb-with-class/ git clone git://github.com/ekmett/eq.git git clone git://github.com/ekmett/data-lens-fd.git git clone git://github.com/ekmett/streams.git git clone git://github.com/alanz/hjsmin.git darcs get http://patch-tag.com/r/byorgey/diagrams-lib ... -- gwern http://www.gwern.net/haskell/Archiving%20GitHub ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] haskellwiki slow/unresponsive
On Mon, Jun 6, 2011 at 4:45 PM, Greg Weber g...@gregweber.info wrote: Gitit uses darcs or git to store data, but through the command line interfaces. Unfortunately to my knowledge darcs does not expose a library interface. Gitit could be made faster and more secure by interfacing with libgit2. Darcs does export a library and pretty much has ever since I first cabalized it; see http://hackage.haskell.org/package/darcs for the module listings. It's not a very useful API, however. I don't know how to use it, and John doesn't know how to use libgit2, I suspect. -- gwern http://www.gwern.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] haskellwiki slow/unresponsive
On Fri, Jun 3, 2011 at 4:17 PM, Eric Rasmussen ericrasmus...@gmail.com wrote: This is a bit of a tangent, but has anyone developed wiki software in Haskell? Gitit is the most developed one, and it's been suggested in the past that hawiki move over. It's not a good idea for a couple reasons, which I've said before but I'll repeat here: 1. Performance; there have been major issues with the Darcs backend, though mostly resolved, and we don't know how well the Git backend would scale either. Gitit has mostly been used with single-users (how I use it) or projects with light traffic (wiki.darcs.net). I don't know why hawiki is slow, but whatever it is is probably either hardware or configuration related - MediaWiki after all powers one of the most popular websites in the world. 2. Security; there have been big holes in Gitit. Some of it is simple immaturity, some of it due to the DVCS backends. Where there is one hole, there are probably more - if there aren't holes in the Gitit code proper, there probably are some in Happstack. There's no reason to think there aren't: security is extremely hard. And in that respect, Mediawiki is simply much more battle-tested. (Most popular websites in the world, again, and one that particularly invites abuse and attack.) 3. The existing hawiki content is Mediawiki centric, relying on templates and MW syntax etc. Templates alone would have to be implemented somehow, and Pandoc's MW parser is, last I heard, pretty limited. Gitit is great for what it is, and I like using it - but it's not something I would rely on for anything vital, and especially not for something which might be attacked. (This isn't paranoia; I deal with spammers every day on hawiki, and c.h.o was rooted recently enough that the memory should still be fresh in our collective minds.) -- gwern http://www.gwern.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] lambdabot hoogle
On Wed, May 25, 2011 at 6:22 AM, Jacek Generowicz jacek.generow...@cern.ch wrote: I had assumed that it connected to a server. It did at one point, but Hoogle had downtime and the local hoogle command was just as good and worked offline. (Maybe my assumption was not entirely unfounded, given that the installation instructions for lambdabot blithely state that you just cabal install lambdabot, nowhere suggesting that you might need to *manually* install some of its dependencies.) Well, does every lambdabot user want mueval and hoogle installed? In those specific cases because they export libraries as well, I could add a dependency on the library; but cabal doesn't support dependencies for pure executable packages. Once I have the hoogle command line version working, it seems that lambdabot truncates its output to just the first 3 lines. Is this normal? Is there a way of customizing or changing this behaviour? It's normal, yeah. Don't want to spam #haskell with 100 lines of useless matches. Configurable? Not really. -- gwern http://www.gwern.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] lambdabot hoogle
On Wed, May 25, 2011 at 11:08 AM, Jacek Generowicz jacek.generow...@cern.ch wrote: Quite possibly not, but it would it be too much to ask, to have the documentation mention that they need to be installed separately if you intend to use them through lambdabot? I've just added them to the dependencies. I've already stumbled across mueval and hoogle as things that need to be installed separately before the full advertized features of lambdabot work. With this experience under my belt and the benefit of hindsight, I vaguely, almost, kinda, maybe see how I could have guessed that the stubborn response A Hoogle error occurred. to any hoogle command in lambdabot, means that I need to install hoogle locally: 'hoogle ...' -- A Hoogle error occurred. == install hoogle. But how on earth was I supposed to guess that in order to make 'check' work, the package to install was 'mueval', given that the error message was Terminated? 'check ...' -- Terminated == install mueval. You weren't really meant to - lambdabot isn't exactly meant for anyone who won't look at the source when something goes wrong. It's only half-maintained by me; I do easy fixes but nothing else since the lambdabot codebase is large and IMO rotten. Hmmm. What other lambdabot features rely on packages that need to be installed separately? Brainfuck and unlambda are separate executables, but they already have deps. -- gwern http://www.gwern.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] lambdabot check
On Tue, May 24, 2011 at 7:00 AM, Jacek Generowicz jacek.generow...@cern.ch wrote: I've installed lambdabot, but check within it seems to be broken: the only answer it ever gives is Terminated. For example: lambdabot check True Terminated lambdabot quickCheck works just fine in a GHCi session: Prelude :m + Test.QuickCheck [...] Prelude quickCheck True [...] +++ OK, passed 100 tests. @check these days goes through mueval. Are you sure mueval is installed working? You can try running the tests.sh script which will exercise the QuickCheck functionality among other things. -- gwern http://www.gwern.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Downloading Haskell repos from GitHub
On Fri, Apr 30, 2010 at 12:02 PM, Gwern Branwen gwe...@gmail.com wrote: On Fri, Apr 30, 2010 at 11:51 AM, Jesper Louis Andersen jesper.louis.ander...@gmail.com wrote: On Fri, Apr 30, 2010 at 5:38 PM, Gwern Branwen gwe...@gmail.com wrote: Nothing in http://develop.github.com/ seems especially useful for grabbing the git:// URLs of all repos by language - just by user. The only real list of repos by language seems to be gotten at via http://github.com/languages/Haskell/updated or http://github.com/languages/Haskell/created . (You might think http://github.com/languages/Haskell would be good, but no, it's just a few random repos by interest and not a full listing.) Github has a REST API for accessing data. Unfortunately it can't give you the wanted breakdown, but I would ask them for it. It is much simpler for you, You mean ask for a new feature? (Just a one-time list is no good since I intend to repeat it regularly to pick up new repos, just like with patch-tag.) and it does not put an extra strain on their servers due to the scraping. Well, it'd only be about 2000 HTTP hits. (98 + (20 * 98)). The downloading of the repos would probably reduce that demand to insignificance, especially the first time around when most of the repos would need to be downloaded. Usually, the github guys are helpful when you have a question. Ultimately, they never did anything about it: http://support.github.com/discussions/email/6782-contact-extending-api-to-easily-get-list-of-repos-by-language So I wrote a TagSoup scraper; then I wrote a long tutorial explaining how I wrote it, step by step. 1. my tutorial: http://www.gwern.net/haskell/Archiving%20GitHub.html 2. the script itself: http://www.gwern.net/haskell/Archiving%20GitHub.html#the-script 3. Reddit submission of #1 for those who prefer to comment there: http://www.reddit.com/r/haskell/comments/g7na5/writing_a_haskell_script_to_download_github/ (While writing the tutorial, I tweaked the script code, so I'm not 100% confident that it still works - it uses too much GitHub bandwidth (and local disk space) for me to re-run it just to see whether it still works. So if anyone does run it, I would appreciate knowing whether it still works.) -- gwern http://www.gwern.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANN: unordered-containers - a new, faster hashing-based containers library
On Wed, Feb 23, 2011 at 1:18 PM, Johan Tibell johan.tib...@gmail.com wrote: Could you manually look at some of them to see if you find something interesting. In particular `Set.size s == 0` (a common use of size in imperative languages) could be replaced by `Set.null s`. You could look at them yourself; I attached the files. I see 6 uses out of ~100 which involve an == 0 -- gwern http://www.gwern.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Why is there no splitSeperator function in Data.List
On Sat, Feb 12, 2011 at 11:00 AM, Robert Clausecker fuz...@gmail.com wrote: Is there any reason, that one can't find a function that splits a list at a seperator in the standard library? I imagined something like this: splitSeperator :: Eq a = a - [a] - [[a]] splitSeperator ',' foo,bar,baz -- [foo,bar,baz] Or something similar? This is needed so often, even if I can implement it in one line, is there any reason why it's not in the libs? See http://hackage.haskell.org/package/split The reason it's not in Data.List is because there are a bazillion different splits one might want (when I was pondering the issue before Brent released it, I had collected something like 8 different proposed splits), so no agreement could ever be reached. -- gwern http://www.gwern.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Haskell Summers of Code retrospective (updated for 2010)
2 years ago in February 2009, I wrote up a history of Summers of Code through 2008 (http://www.haskell.org/pipermail/haskell-cafe/2009-February/055489.html). But the Wheel turns, and years come and pass, leaving memories that fade into 404s; a wind rose in Mountain View, whispering of the coming Summer... I have considerably expanded and updated the coverage: http://www.gwern.net/Haskell%20Summer%20of%20Code.html It now covers the 2009 2010 SoCs, adds scads of links, flips the appraisal of some of the older SoCs as time passed and more info came to light, and adds a section discussing 12 proposals from the subreddit Trac. (It's long enough that I don't feel comfortable copying it inline as I did 2 years ago.) -- gwern http://www.gwern.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Problem with xhtml 1.5.1.1: html tags are split
On Thu, May 13, 2010 at 11:38 AM, Gwern Branwen gwe...@gmail.com wrote: On Tue, May 11, 2010 at 3:00 AM, Bjorn Bringert bj...@bringert.net wrote: I support finding a new maintainer. Alright; as the old maintainer, I guess it falls on you to advertise on -cafe and libraries. Has a request gone out yet? I didn't notice anything (maybe it got lost in all the recent haskell.org downtime), and the current Hackage page of xhtml is still listing Bjorn. Anyway, John MacFarlane has found a workaround which he's implemented in HEAD Pandoc (http://code.google.com/p/pandoc/issues/detail?id=134); from http://groups.google.com/group/pandoc-discuss/browse_frm/thread/915586b5c5e264b6# : Many people have wanted pandoc to produce more normal HTML output, without nesting, but with line breaks between block elements (where they aren't semantically significant). Something like this: ul lia a href=/foolink/a/li lianother list item/li /ul I've found that I can get this kind of output, even using Text.XHtml's renderer, by modifying the writer to insert raw newlines after block elements, and using 'showHtmlFragment' rather than 'prettyHtmlFragment'. This may be useful for other people to know. (There are quite a few users of xhtml: http://bifunctor.homelinux.net/~roel/cgi-bin/hackage-scripts/revdeps/xhtml-3000.2.0.1#direct ) -- gwern http://www.gwern.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Automatically move cursor focus in split window in haskell-mode in emacs on load (C-c C-l) command?
On Sun, Jan 30, 2011 at 11:30 AM, JETkoten jetko...@gmail.com wrote: The way it defaults to now is that the cursor stays in the topmost editing half of the split screen, and I inevitably begin typing and mess up my code and have to do some backspacing and then mouse over to the bottom half. :) I checked on #haskell and #emacs last night, and someone suggested either doing it with elisp or keyboard macros, but I'm not sure how to do the first, and I think the second is not what I'm looking for. I'd like for haskell-mode to otherwise remain the same, and to still use the same C-c C-l key sequence, but I'd just like it to always be set up to add the step in the load sequence of jumping the cursor focus down to the lower half of the split for me. From my .emacs; ;Default behaviour is to always jump to the GHCi window. ;Jump back automatically unless errors. (defadvice haskell-ghci-load-file (after name) (other-window 1)) (ad-activate 'haskell-ghci-load-file t) -- gwern http://www.gwern.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Building lambdabot
On Thu, Jan 20, 2011 at 3:24 AM, Max Bolingbroke batterseapo...@hotmail.com wrote: On 20 January 2011 01:51, Gwern Branwen gwe...@gmail.com wrote: It had a lot of issues which meant it wouldn't build anywhere, where at least the Hackage version worked at some point. I spent this evening working on fixing issues (rewriting the show package to use QuickCheck 2 rather than QuickCheck 1 was not fun!) and have uploaded a lambdabot and show that compile for me on GHC 6.12.1 The show package almost compiles on GHC 7, but: * You need to loosen the base upper bound to 4.4 * If using base = 4, you need to depend on the syb package as well (current version 0.3) Would this break GHC 6.12 builds? Since I do not have GHC 7 installed and, given the breakage I experienced when I installed it the other day and tried to cabal-install my usual tools, will not have it installed any time soon, I am leery of any GHC 7-related changes. data-memocombinators is only the tip of the iceberg; I believe much of lambdabot would need modifications. (Apparently Control.OldException has gone away, which alone guarantees many changes.) So there wouldn't be much point to changing show. -- gwern http://www.gwern.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Building lambdabot
On Thu, Jan 20, 2011 at 12:45 PM, Max Bolingbroke batterseapo...@hotmail.com wrote: On 20 January 2011 17:30, Gwern Branwen gwe...@gmail.com wrote: * You need to loosen the base upper bound to 4.4 * If using base = 4, you need to depend on the syb package as well (current version 0.3) Would this break GHC 6.12 builds? Thats why I suggested the flag stanza. Cabal has a weird kind of flag semantics where it will try every possible combination of flags until it finds one that builds. The solution I suggested uses this behaviour to either depend on base = 4 4.4 WITH syb, OR base 4 WITHOUT syb. Because of the default flag setting of True, the first possibility will be tried first, but it if fails Cabal will just fall back on base 4. In short, it should work perfectly for either GHC 7 or 6.12 clients (modulo syntax issues - I haven't actually tried the syntax I sent you). No, there's another issue. I've recorded this version; hunk ./show/show.cabal 25 +Flag base4 + Description: Build with base-4 + Default: False + hunk ./show/show.cabal 32 - build-depends: base4, random, QuickCheck=2.4, smallcheck=0.4 + build-depends: random, QuickCheck=2.4, smallcheck=0.4 + if flag(base4) +build-depends: base=4 4.4, syb = 0.3 0.4 + else +build-depends: base4 Notice the flag defaults to False, not True. When I tried it with True, I got: $ cabal install Resolving dependencies... cabal: dependencies conflict: base-3.0.3.2 requires syb ==0.1.0.2 however syb-0.1.0.2 was excluded because syb-0.3 was selected instead syb-0.1.0.2 was excluded because show-0.4.1 requires syb ==0.3.* -- gwern http://www.gwern.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Building lambdabot
On Thu, Jan 20, 2011 at 5:33 PM, Max Bolingbroke batterseapo...@hotmail.com wrote: On 20 January 2011 20:50, Gwern Branwen gwe...@gmail.com wrote: Notice the flag defaults to False, not True. When I tried it with True, I got: $ cabal install Resolving dependencies... cabal: dependencies conflict: base-3.0.3.2 requires syb ==0.1.0.2 however syb-0.1.0.2 was excluded because syb-0.3 was selected instead syb-0.1.0.2 was excluded because show-0.4.1 requires syb ==0.3.* Suprising. It certainly seems to contradict my understanding of how Cabal works (which is derived from http://www.haskell.org/cabal/release/cabal-latest/doc/users-guide/authors.html#conditional-resolution) Anyway, I'm glad that you have recorded a patch which at least gives GHC 7 a chance of working. If I knew where the repo was I would try it out (it doesn't seem to be linked anywhere from http://hackage.haskell.org/packages/archive/show/0.4.1/show.cabal). It's just a folder in the lambdabot repo, as is lambdabot-utils and unlambda and brainfuck. -- gwern http://www.gwern.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Building lambdabot
On Tue, Jan 18, 2011 at 3:41 PM, Max Bolingbroke batterseapo...@hotmail.com wrote: That sounds like a good thing to do. Also, oo you know if there's any reason that the most recent lambdabot is not pushed to Hackage? That might make things even easier for others who wish to install it. It certainly confused me! Cheers, Max It had a lot of issues which meant it wouldn't build anywhere, where at least the Hackage version worked at some point. I spent this evening working on fixing issues (rewriting the show package to use QuickCheck 2 rather than QuickCheck 1 was not fun!) and have uploaded a lambdabot and show that compile for me on GHC 6.12.1 -- gwern http://www.gwern.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Building lambdabot
On Fri, Jan 7, 2011 at 11:00 AM, Max Bolingbroke batterseapo...@hotmail.com wrote: Well, I tried to see if I could reproduce your problem but didn't get to this stage. It looks like v4.2.2.1 from Hackage hasn't been updated for donkeys years and breaks massively because of at least the new exceptions library, mtl 2.0 and the syb package being split off from base. I haven't commented before because most of the issues seemed to be Mac specific, which I know nothing about, but avoid the Hackage packages for lambdabot. You should be working out of darcs for lambdabot and its split-out packages like show or unlambda: http://code.haskell.org/lambdabot/ Darcs lambdabot ought to work reasonably well with GHC 6.12.1, which is what I have. -- gwern http://www.gwern.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] ANN: archiver 0.1 and 0.2
I'd like to announce a small utility and library which builds on my
WebArchive plugin for gitit: archiver
http://hackage.haskell.org/package/archiver Source is available via
`darcs get http://community.haskell.org/~gwern/archiver/`.
The library half is a simple wrapper around the appropriate HTTP
requests; the executable half reads a text file and loops as it
(slowly) fires off requests and deletes the appropriate URL.
That is, 'archiver' is a daemon which will process a specified text
file, each line of which is a URL, and will one by one request that
the URLs be archived or spidered by http://www.webcitation.org * and
http://www.archive.org ** for future reference. That is, WebCite and
the IA will store a copy of the HTML and hopefully all the non-dynamic
resources the web pages need. (An example would be
http://bits.blogs.nytimes.com/2010/12/07/palm-is-far-from-game-over-says-former-chief/
and http://webcitation.org/5ur7ifr12)
Usage of archiver might look like `while true; do archiver ~/.urls.txt
gwe...@gmail.com; done`***.
There are a number of ways to populate the source text file. For
example, I have a script `firefox-urls` which is called in my crontab
every hour, and which looks like this:
#!/bin/sh
set -e
cp `find ~/.mozilla/ -name places.sqlite` ~/
sqlite3 places.sqlite SELECT url FROM moz_places, moz_historyvisits \
WHERE moz_places.id =
moz_historyvisits.place_id and visit_date strftime('%s','now','-1
day')*100 ORDER by \
visit_date; ~/.urls.txt
rm ~/places.sqlite
This gets all visited URLs in the last time period and prints them out
to the file for archiver to process. Hence, everything I browse is
backed-up.
More useful perhaps is a script to extract external links from
Markdown files and print them to stdout:
import System.Environment (getArgs)
import Text.Pandoc (defaultParserState, processWithM,
readMarkdown, Inline(Link), Pandoc)
main = getArgs = mapM readFile = mapM_ analyzePage
analyzePage x = processWithM printLinks (readMarkdown defaultParserState x)
printLinks (Link _ (x, _)) = putStrLn x return undefined
printLinks x = return x
So now I can take `find . -name *.page`, pass the 100 or so Markdown
files in my wiki as arguments, and add the thousand or so external
links to the archiver queue (eg. `find . -name *.page | xargs
runhaskell link-extractor.hs ~/.urls.txt`); they will eventually be
archived/backed up and when combined with a tool like link-checker
means that there never need be any broken links since one can either
find a live link or use the archived version.
General comments: I've used archiver for a number of weeks now. It has
never caught up with my Firefox-generated backlog since WebCite seems
to have IP-based throttling so you can't request more often than once
per 20 seconds, according to my experiments, so I removed the hinotify
'watch file' functionality. It may be I was too hasty in removing it.
* http://en.wikipedia.org/wiki/WebCite
** http://en.wikipedia.org/wiki/Internet_Archive
*** There are sporadic exceptions from somewhere in the network or
HTTP libraries, I think
http://linkchecker.sourceforge.net/
--
gwern
http://www.gwern.net
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Re: [Haskell-cafe] Haskell and a complete mail client lib?
2010/10/27 Don Stewart d...@galois.com: gue.schmidt: Hi all, do we Haskellers have a complete Mail client library? As always, look on Hackage: http://www.google.com/search?hl=enas_sitesearch=hackage.haskell.org/packageas_q=email Besides the tagged packages, there are a few other places one could look if one searched the package listings carefully: - http://hackage.haskell.org/package/HaskellNet - http://hackage.haskell.org/package/postmaster - http://hackage.haskell.org/package/pop3-client Are any of these *complete*? Dunno. But I suspect you do not actually need to do everything one could possibly do with email. -- gwern http://www.gwern.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] back doors into the IO monad
On Sun, Oct 24, 2010 at 10:22 AM, Nicolas Pouillard nicolas.pouill...@gmail.com wrote: On Sun, 24 Oct 2010 00:28:37 +0200, Manlio Perillo manlio_peri...@libero.it wrote: Hi. What are the available methods to execute IO actions from pure code? I know only unsafePerformIO and foreign import (to call a non pure foreign function). unsafeCoerce is a back door for almost everything. The mueval tests also include this fun example: 'runST (unsafeIOToST (readFile /etc/passwd))' -- gwern http://www.gwern.net/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Haskell web development entries on the Wiki
On Sat, Oct 2, 2010 at 4:13 PM, Michael Snoyman mich...@snoyman.com wrote: I understand the advantages to splitting into multiple pages, but on the other hand it *does* make it more difficult to locate information. My guess is a good search function on the wiki will make that point moot. Overall, looks like you've done a great job, thanks! A few minor comments: * Should we rename HAppS to Happstack everywhere? I think we should. No one is using the old HAppS code, so references are just misleading. -- gwern ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Haskell Platform, Hackage and Cabal : The 2nd Year : Status Report
On Fri, Oct 1, 2010 at 5:00 PM, Matthias Kilian k...@outback.escape.de wrote: On Fri, Oct 01, 2010 at 09:29:32PM +0100, Malcolm Wallace wrote: The slides are here: http://donsbot.wordpress.com/2010/10/01/hackage-cabal-and-the-haskell-platform-the-second-year/ And the video is here: http://www.vimeo.com/15462768 And is there any way to just *download* the video? For people not using adobe flash? I believe Vimeo lets logged in users download the video. For example, when I visit the link I see: * 640x360, 496.1MB * Uploaded Fri October 01, 2010 * Download this video -- gwern ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Haskell at bettercodes.org
On Wed, Sep 22, 2010 at 11:15 AM, David Sankel cam...@gmail.com wrote: I can understand why it would be slightly better for any website to not require JavaScript clients since it becomes a bit more accessible. I'm confused though about why being a professional developer site would make this feature even more important. Care to expand on that? Thanks, David I would guess it's because developers are much more likely to be using all manner of weird wonderful methods of access, like a text browser (elinks) from a command-line over a packet-radio link to the sub-Saharan bush, as they try to develop a script to download the site and compile everything into Brainfuck. Or something. A 'normal' person, on the other hand, wouldn't know a non-Safari/Firefox/IE/Chrome browser if it smacked them upside the head. -- gwern ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Changing my Profile
On Tue, Aug 24, 2010 at 2:48 AM, David Virebayre dav.vire+hask...@gmail.com wrote: 2010/8/23 Christopher Done chrisd...@googlemail.com: Any suggestions would be appreciated. Isn't there the possibility to mute a thread in gmail ? You need to activate keyboard shortcuts, then ? gives you a list of keys. m seems to be used to mute a thread, but I didn't try it so I don't know what it does exactly. David. Muting applies a 'mute' label and removes any future emails from your inbox. However, it doesn't change the read/unread status. If I were to try to tackle this problem in Gmail, I think what I would do is try to create a filter which makes only emails sent to both gwe...@gmail.com and haskell-cafe@haskell.org, say, and have the filter remove from inbox mark read matching emails. So in theory I'd only see the one copy sent by haskell.org. (If one can't directly match on being sent to 2 addresses, I'm sure there's some more indirect approach using labels and multiple filters.) There's also 1 or 2 mailman options which do something similar with suppressing duplicates. -- gwern ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: The site has been exploited (again)
On Sun, Jul 11, 2010 at 2:28 PM, Mike Dillon m...@embody.org wrote: begin Mike Dillon quotation: Being that there is only one active admin on the Haskell.org wiki (User:Ashley Y), I believe the fact that this page is editable by any user is a policy decision to allow the community to contribute. The page could be protected, but then only two administrators could edit it (assuming John Peterson decided to become active again after two years of not working on the wiki): http://www.haskell.org/haskellwiki/?title=Special%3AListusersgroup=sysop As for whether or not moving this particular wiki to a Haskell-based solution would be a good idea, I don't see it being a win. I don't know of any Haskell-based wikis that support MediaWiki syntax, so the effort would involve converting all the existing content to some other format. Being that MediaWiki's syntax is the most widespread wiki syntax at the moment, I don't see how that would do anything but make it harder for people to contribute. One more thing. On a wiki with active administrators, this user would have been blocked. That hasn't happened. The last block was in August 2009: http://www.haskell.org/haskellwiki/?title=Special%3ALogtype=block If there is not someone regularly watching the wiki at all times, it would probably be prudent to protect some of the higher profile pages once there are more admins able to edit them. -md Ashley has made me admin; I've spent the last 1.5 hours deleting all the vandalism and indef blocking the accounts. I have Recent Changes in my RSS reader, so hopefully in the future there will be no greater than 24 hours delay before vandalism is dealt with. A MW upgrade will also help (eg. currently checkuser* seems to be unavailable). * http://www.mediawiki.org/wiki/Extension:CheckUser -- gwern ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] HaskellWiki and Wikipedia
On Sat, Jun 19, 2010 at 2:45 PM, Mike Dillon m...@embody.org wrote: Actually, it looks like MediaWiki:Newarticletext probably needs to be edited as well since that's what you see when you click through a red link. The others are for the top text after a search using Go and Search respectively. Unfortunately, this MediaWiki install doesn't appear to have interwiki links enabled; either that or the default wikipedia: interwiki doesn't work in this version or configuration. It's also horribly ancient, so it's hard to find docs on what is actually supported in the installed version since most docs out there reflect at least some of the changes that have happened in the software in the last five years. -md Interwiki link do work, however, the interwiki map seems to be extremely old. For example, an interwiki to Ward's Wiki (Meatball), one of the oldest interwikis around, will work: http://haskell.org/haskellwiki/?title=User%3AGwerndiff=35010oldid=11424 -- gwern ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Language Shootout reverse-complement benchmark
On Tue, Jun 1, 2010 at 10:25 AM, David Leimbach leim...@gmail.com wrote: I'm still trying to figure out what the point of the shootout really is. If there's no dedicated folks working with a language there, trying to make things run faster, a language will come out looking inefficient potentially. There's a lot of compile flags and optimizations that can make a difference in probably all of the languages listed on that page. 'Out of the crooked timber of humanity, no straight thing was ever made.' I guess all you can get from the shootout is a sense of what a particular language or set of tools is capable of in the hands of the programmers who submit implementations. It doesn't really give you a concrete idea as to how to evaluate a programming language. It does still seem kind of fun for some reason though :-) Dave The Shootout has a number of valuable purposes: 1) Concrete evidence that language X *can*, somehow, be as fast as language Y 2) Public examples of techniques to do #1, again concrete 3) Exposes where libraries/compilers can do better (this has happened many times with GHC and Haskell libraries) 4) Motivates people to work on creating/fixing #2 and #3 -- gwern ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] How efficient is read?
On Tue, May 11, 2010 at 12:16 AM, Tom Hawkins tomahawk...@gmail.com wrote:
The tarball was missing its Rules.hs; as it happens, GHC has a module
named Rules.hs as well, hence the confusing error. I've uploaded a
fresh one that should work.
Thanks. This builds and installs fine.
But I think there is something wrong with the generated parser. It
doesn't look for (..) groupings. For example:
data Something = Something Int (Maybe String)
deriving Show {-! derive : Parse !-}
There is nothing in the generated parser to look for parens around the
Maybe in case it is a (Just string).
Am I missing something?
I don't know. If you could check whether the original Drift has that
error as well, then I suspect Drift's author, Meachem, would be
interested to know. (I only maintain drift-cabalized as a packaging
fork; I tried not to change any actual functionality.)
--
gwern
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Re: [Haskell-cafe] How efficient is read?
On Mon, May 10, 2010 at 4:50 PM, Tom Hawkins tomahawk...@gmail.com wrote: In fact, if you just want Read-like functionality for a set of Haskell datatypes, use polyparse: the DrIFT tool can derive polyparse's Text.Parse class (the equivalent of Read) for you, so you do not even need to write the parser yourself! Cabal install DrIFT-cabalized complains. What is the module Rules? I've never seen it before. Is there a quick fix? I didn't see a build-depends line in my ~/.cabal/config file. e0082...@e0082888-laptop:~$ cabal install DrIFT-cabalized Resolving dependencies... Configuring DrIFT-cabalized-2.2.3.1... Preprocessing executables for DrIFT-cabalized-2.2.3.1... Building DrIFT-cabalized-2.2.3.1... src/DrIFT.hs:19:17: Could not find module `Rules': It is a member of the hidden package `ghc-6.12.2'. Perhaps you need to add `ghc' 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: DrIFT-cabalized-2.2.3.1 failed during the building phase. The exception was: ExitFailure 1 The tarball was missing its Rules.hs; as it happens, GHC has a module named Rules.hs as well, hence the confusing error. I've uploaded a fresh one that should work. -- gwern ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Haskell and scripting
On Wed, May 5, 2010 at 4:29 PM, Limestraël limestr...@gmail.com wrote: Yes, the xmonad approach is very neat, but I see 2 major (IMO) drawbacks to it: 1) The end-user has to have GHC, and all the necessary libraries to compile the configuration 2) A scripting language should be simple and QUICK to learn : Haskell is clean, powerful but its learning takes time For basic customization, many XMonad users (judging by questions on #xmonad) have little to no Haskell experience and get by. Further, it's easier to step down the power than to increase it; because we use Haskell, it's possible to have simpler configuration options like xmonad-light* * http://braincrater.wordpress.com/2008/08/28/announcing-xmonad-light/ isn't a very good explanation of xmonad-light, but I don't know of any others -- gwern ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Haskell and scripting
On Mon, May 3, 2010 at 5:47 PM, Kyle Murphy orc...@gmail.com wrote: That's also the approach Yi uses. I'm fairly certain there's a library on hackage that makes writing up programs in that style fairly trivial, http://hackage.haskell.org/package/dyre -- gwern ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Typing Haskell in Haskell
On Sat, May 1, 2010 at 10:05 AM, Aaron Gray aaronngray.li...@googlemail.com wrote: Hi, I am relatively new to Haskell. I am attempting to get Typing Haskell in Haskell to work on HUGS or GHC. http://web.cecs.pdx.edu/~mpj/thih/ I am getting an error on loading SourcePrelude :- Hugs :l SourcePrelude ERROR .\PPrint.hs - Can't find imported module Pretty And I cannot find a Pretty module, the module and Language.Haskell.Pretty does not seem to be what is required. Any help welcome, Aaron I strongly suggest you only bother with GHC and not try Hugs. As far as THIH, I cabalized and uploaded it a while ago: http://hackage.haskell.org/package/thih You should have better luck with that. -- gwern ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Downloading Haskell repos from GitHub
Along the lines of http://blog.patch-tag.com/2010/03/13/mirroring-patch-tag/ for downloading all patch-tag.com repositories, I've begun to wonder how to download all Github repositories since more and more people seem to be using it. Nothing in http://develop.github.com/ seems especially useful for grabbing the git:// URLs of all repos by language - just by user. The only real list of repos by language seems to be gotten at via http://github.com/languages/Haskell/updated or http://github.com/languages/Haskell/created . (You might think http://github.com/languages/Haskell would be good, but no, it's just a few random repos by interest and not a full listing.) I looked at the HTML, and it looks possible to use tagsoup to get all 98 pages and then parse the entries to get the HTTP URLs of the repos, and then turn *that* into git:// URLs suitable for shelling out to 'git clone', but I can't help but wonder if maybe there's a better approach someone more familiar with Github would know. -- gwern ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Downloading Haskell repos from GitHub
On Fri, Apr 30, 2010 at 11:51 AM, Jesper Louis Andersen jesper.louis.ander...@gmail.com wrote: On Fri, Apr 30, 2010 at 5:38 PM, Gwern Branwen gwe...@gmail.com wrote: Nothing in http://develop.github.com/ seems especially useful for grabbing the git:// URLs of all repos by language - just by user. The only real list of repos by language seems to be gotten at via http://github.com/languages/Haskell/updated or http://github.com/languages/Haskell/created . (You might think http://github.com/languages/Haskell would be good, but no, it's just a few random repos by interest and not a full listing.) Github has a REST API for accessing data. Unfortunately it can't give you the wanted breakdown, but I would ask them for it. It is much simpler for you, You mean ask for a new feature? (Just a one-time list is no good since I intend to repeat it regularly to pick up new repos, just like with patch-tag.) and it does not put an extra strain on their servers due to the scraping. Well, it'd only be about 2000 HTTP hits. (98 + (20 * 98)). The downloading of the repos would probably reduce that demand to insignificance, especially the first time around when most of the repos would need to be downloaded. Usually, the github guys are helpful when you have a question. Any suggested method besides the obvious http://github.com/contact ? -- gwern ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] The instability of Haskell libraries
On Fri, Apr 23, 2010 at 7:17 PM, Ivan Lazar Miljenovic ivan.miljeno...@gmail.com wrote: Keith Sheppard keiths...@gmail.com writes: Set up a server to poll the Source-Repository head of every hackage package that includes one in it's cabal file, then rerun the build any time a change is detected. This may be a good excuse to implement a pluggable continuous integration server in haskell too along the lines of what Hudson is for java... maybe an idea for the next GSoC Several problems with this: 1) Is this going to support every VCS under the sun? We only need to support 3 or 4 to get 99% of the stuff on Hackage that lives in a VCS at all. 2) Not all head repositories are kept stable/buildable at all times. Perfect, meet better. Wait, no no - aw goddammit Perfect! Why do you do this every single time? *You* get to mop the floor this time. 3) I can see this getting expensive wrt space and network usage. Not really. I do much the same thing locally. Most repos hardly ever change. My own local repos - which includes all of patch-tag, a few GHCs, some intermediate builds, and whatnot - is about 4.5G. By my calculations* that's about 25¢ of hard-drive space. * http://forre.st/storage#sata -- gwern ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] problem with cabal on snow leopard
On Sat, Apr 17, 2010 at 5:30 PM, Carter Schonwald carter.schonw...@gmail.com wrote: Hello all, I can't seem to find it documented anywhere as to the default directories that cabal puts its information in (its certainly not in ~/.cabal ), as I'm finding that even when I try to do a reinstall of the haskell platform, cabal thinks that all the libraries i removed are still there. how can i fix this? thanks -Carter ~/.cabal doesn't store regular Haskell stuff; if you try one of the few uncabalized autotools-based Haskell packages, you'd see your other Cabal-based libs progs picking it up. Cabal installs stuff and registers it with GHC, which maintains the master database of what's installed; eg. 'ghc-pkg list'. This is usually kept in ~/.ghc: find ~/.ghc/ : .ghc/ .ghc/ghci_history .ghc/i386-linux-6.10.4 .ghc/i386-linux-6.10.4/package.conf -- gwern ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] What is the consensus about -fwarn-unused-do-bind ?
On Fri, Apr 9, 2010 at 10:20 AM, Neil Brown nc...@kent.ac.uk wrote: Ivan Lazar Miljenovic wrote: As of 6.12.1, the new -fwarn-unused-do-bind warning is activated with -Wall. This is based off a bug report by Neil Mitchell: http://hackage.haskell.org/trac/ghc/ticket/3263 . However, does it make sense for this to be turned on with -Wall? For starters, why should this warning apply only to do blocks and not to explicit usage of , etc.? That is, the following code (as specified in the above bug report) generates an error: do doesFileExist foo return 1 yet this doesn't: doesFileExist foo return 1 The comments in that bug report actually mention My patch does not warn on uses of , only in do-notation, where the situation is more clear cut. I take to be an explicit sign that the user wants to ignore the result of the first action, whereas in do-notation it may be an accident. So I think it was the right decision. Relevant link: http://neilmitchell.blogspot.com/2008/12/mapm-mapm-and-monadic-statements.html 2. Use some function of type (Monad m) = m a - m () instead of doing _ -. 3. Duplicate the parser combinators in question so that I have one version that returns a value and another that does the main parser and then returns (); then use this second combinator in do blocks where I don't care about the returned value. 4. Put -fno-warn-unused-do-bind in the .cabal file. The first two options don't appeal to me as being excessive usage of boilerplate; the third involves too much code duplication. However, I am loath to just go and disable a warning globally. I'd be tempted by number two, but I it's more typing to write ignore $ than _ -, so maybe 1 is the best option after all. I've frequently encountered the annoyance of monadic return values -- but to satisfy type signatures rather than avoid this warning. For example, I have a CHP parallel operator: (||) :: CHP a - CHP b - CHP (a,b) and a function writeChannel :: Chanout a - a - CHP (). But if you try to write a function like: It's actually going to be named 'void': http://hackage.haskell.org/trac/ghc/ticket/3292 I don't think it's made it into a stable release yet. -- gwern ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Simple game: a monad for each player
On Thu, Apr 8, 2010 at 4:08 PM, Yves Parès limestr...@gmail.com wrote:
Hello Cafe,
I have a question about program design.
Let's say I have a simple sequential game (a TicTacToe for instance, but
with more than 2 players).
I have a Player datatype which is like:
data Player m = Player {
plName :: String, -- unique for each player
plTurn :: GameGrid - m Move -- called whenever the player must play
}
As you may guess, the 'm' type variable is intended to be a Monad.
The goal is that every player has his own monad. For instance :
- a human player needs to interact with the program, so its monad would be
IO, or an instance of MonadIO.
- a network player, which transparently sends the game state and receives
moves through network, must also have access to IO to play.
- an AI doesn't need to interact with the outside of the program, so its
monad can be the one we want (e.g. Identity).
First, do you think it is a good way to design the program?
I want the game to be totally independent of the players who are currently
playing. They can be humans, AIs, AIs and network players and humans, and so
on.
But when running the game, the program cannot switch from a player's monad
to another.
If we want every player to run in his own monad, I think we have to stack
every players' monad, and lift their actions each time they have to play.
This is not a problem, the sole condition now is that every player has type:
(Monad m, MonadTrans m) = Player m.
But I think it's a little bit of overkill, and it may be a little bit
complicated to implement such a thing.
What I try to avoid is having every player running in IO monad.
Do you have any suggestion?
-
Yves Parès
Your desires remind me of the MonadPrompt package
http://hackage.haskell.org/package/MonadPrompt, which IIRC, has been
used in some game demos to provide abstraction from IO/test
harness/pure AI etc.
--
gwern
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Re: [Haskell-cafe] [OT?] Haskell-inspired functions for BASH
On Tue, Apr 6, 2010 at 11:17 AM, Stephen Tetley stephen.tet...@gmail.com wrote: On 6 April 2010 15:09, Mario Blažević mblaze...@stilo.com wrote: A question of my own: is there any written design (an academic paper would be perfect) of a functional shell language? Olin Shivers has written a detailed paper on Scsh. ftp://www-swiss.ai.mit.edu/pub/su/scsh/scsh-paper.ps The link might be down permanently (it is for me at the moment), maybe the paper is on Citeseer or similar. There is also the Scsh manual. Best wishes Stephen The Scsh manual is worth reading just for the introductory material. Part of the problem is that both Clean and Scheme have relatively easy and powerful 'eval' ability. (Esther exploits the interesting feature of Clean that lets you serialize functions to disk.) Haskell doesn't, so much. The GHC API isn't too great to work with here; it's hard enough to evaluate straight Haskell fragments, and to serve as a shell, you really need new syntax; for example, you want literals for program names. (Who would use a shell which forces you to write 'run ghci [foo.lhs]', instead of 'ghci foo.lhs'?) But many filenames break in Haskell; 'ssh-agent', 'g++-4.4', 'bf_tar', etc. -- gwern ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Hackage accounts and real names
On Sun, Apr 4, 2010 at 5:28 PM, David House dmho...@gmail.com wrote: Hi, An issue came up on #haskell recently with Hackage accounts requiring real names. The person in question (who didn't send this email as he's wishing to remain anonymous) applied for a Hackage account and was turned down, as he refused to offer his real name for the username. Those of us in the conversation thought this a bit of an odd policy, and were wondering where this came from. It also emerged that a couple of other people had been held back from getting Hackage accounts because of this reason. It must've been put in place in the past year or two; I've never made any bones about using a pseudonym, and I had no trouble getting a Hackage account back when it was starting up. -- gwern ___ 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 Thu, Apr 1, 2010 at 11:13 AM, Jeremy Shaw jer...@n-heptane.com wrote: fps is what we now call bytestring. Alas, hsplugins is dead. hsplugins is useful, but needs to be rewritten for modern GHC :( - jeremy I never looked into hsplugins too carefully. Did it offer anything that Hint doesn't now offer? -- gwern ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANN: Salvia-1.0.0
On Tue, Mar 23, 2010 at 9:27 AM, Bas van Dijk v.dijk@gmail.com wrote: On Tue, Mar 23, 2010 at 2:13 PM, Sebastiaan Visser sfvis...@cs.uu.nl wrote: Nice! This is certainly worth it. I'm glad you like it. Sebastiaan, I made the same mistake as threadmanager does: I forgot to block before installing the deleteMyPid exception handler in the forked thread. I added a new patch that adds the necessary block and unblock: http://bifunctor.homelinux.net/~bas/salvia/ BTW What's the git equivalent of 'darcs send -o filename' which saves the patches to filename? I would rather send my patches as email attachements instead of copying my repository to my webserver. (Note this is the first time I used git) I use ' git format-patch origin'. -- gwern ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Prelude.undefined
On Wed, Mar 3, 2010 at 10:56 AM, Tom Hawkins tomahawk...@gmail.com wrote: On Wed, Mar 3, 2010 at 7:24 AM, Alexander Dunlap alexander.dun...@gmail.com wrote: On Tue, Mar 2, 2010 at 9:06 PM, Tom Hawkins tomahawk...@gmail.com wrote: How do I track down an reference to an undefined value? My program must not be using a library correctly because the program makes no direct use of 'undefined'. Running with +RTS -xc yields: While the debugger, etc., are very useful tools, I find that often the easiest way to track down this sort of bug is to test your code function-by-function. The debugger was not that helpful, so I may have to resort to this. Is there any work being done to improve reporting for these type of errors? It seems to be a fairly common problem. You try the Interlude? http://hackage.haskell.org/package/interlude -- gwern ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Has anybody translated Douglas Hofstadter's Scientific American articles introducting Scheme to a general audience into Haskell?
On Tue, Mar 2, 2010 at 1:04 AM, Benjamin L. Russell dekudekup...@yahoo.com wrote: There is an interesting, if somewhat dated, suggestion on Lambda the Ultimate (see http://lambda-the-ultimate.org/node/1748) that someone translate Doug Hofstadter's Scientific American columns introducing Scheme to a general audience into Haskell. (I came across this link while adding full titles and links to the HaskellWiki Books and tutorials page (see http://www.haskell.org/haskellwiki/Books_and_tutorials), where I clicked on the link to Tutorials (see http://www.haskell.org/haskellwiki/Tutorials), which contained a link to a Haskell vs. Scheme (see http://www.reddit.com/r/programming/tb/nq1k) article, which described the post containing the suggestion.) According to a comment by Ehud Lamm (see http://lambda-the-ultimate.org/node/1748#comment-21292) on the above post, the columns are in Hoftstadter's book _Metamagical Themas: Questing For The Essence Of Mind And Pattern_ [1] (see http://www.amazon.com/Metamagical-Themas-Questing-Essence-Pattern/dp/0465045669). Has anybody translated Hofstadter's articles from Scheme into Haskell? -- Benjamin L. Russell I have scans of the column and have meant to translate them; but you know how it is... -- gwern ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Function to detect duplicates
2010/2/23 Jonas Almström Duregård jonas.dureg...@gmail.com: Hi Rafael, I assume you will perform this operation on some very large lists, or performance would not be an issue. Have you tested if your optimized version is better than your initial one? You should compare your implementation against something like this: import qualified Data.Set as Set noneRepeated :: (Ord a) = [a] - Bool noneRepeated = accum Set.empty where accum _ [] = True accum s (x:xs) | Set.member x s = False | otherwise = accum (Set.insert x s) xs Also there is some discussion about the nub function that relates to this topic, e.g. http://buffered.io/2008/07/28/a-better-nub/. /Jonas Or better yet, http://www.haskell.org/pipermail/libraries/2008-October/010778.html Much more thorough and practical w/r/t to actually getting faster nubs in the libraries. -- gwern ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] What happened in Ohloh?
On Fri, Feb 19, 2010 at 5:20 PM, Paul Johnson p...@cogito.org.uk wrote: If you go to http://www.ohloh.net/languages/compare?l0=haskellmeasure=projects and look at the number (not percentage) of Haskell projects you see it rise exponentially until the start of 2008 and then suddenly drop away. Does anyone know what happened? Assuming this is just an artefact because they aren't scanning Haskell project hosts, can we get them to fix it? I believe in early 2008 Don Stewart was on a kick where he used tailor to convert Darcs repos of Haskell projects to Git repos (which Ohloh understands), and he's stopped doing that. The fix would involve making their software understand darcs; their response hasn't been too enthusiastic or helpful (basically, 'if you guys do all the work and meet our idiosyncratic standards, maybe we'll use it'): http://www.ohloh.net/forums/3491/topics/1138?page=2 I'd like to use this kind of graph at work as evidence that Haskell is on a growth trajectory. Paul. -- gwern ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Haskell and the Job Market, e.g. with Google
On Thu, Feb 11, 2010 at 11:49 AM, Hans van Thiel hthiel.c...@zonnet.nl wrote: Hello, Somewhat in response to the original post about Haskell engineers I, II and III. This confirms the remark that Haskell experience is now being appreciated, though not (yet) used (very much). Steven Grant, recruiter from Google, asked me to bring to his attention anyone who might be suitable, so that's what I'm doing. start quote We are currently aggressively recruiting for a large number of engineers in EMEA. I spotted your extensive open source experience and was particularily interested to see you have worked with Haskell. I am not looking for a Haskell developer but more interested in people that have worked in exotic languages such as Haskell or Erlang or Scheme. The roles we have are heavily open sourced based and will be mainly working with Python, C, Linux, shell etc and are based in Dublin, London or Zurich. If you have any interest in discussing these further, drop me an email to stevengr...@google.com and we can discuss. end quote From a second email: start quote The job specs are below. http://www.google.ie/support/jobs/bin/answer.py?answer=34884 http://www.google.ie/support/jobs/bin/answer.py?answer=34883 The roles are within a very specialist team within Google. They are a hybrid type role and are responsible for making our products reliable scalable and more efficient. end quote Get in touch with Steven: Steven Grant European IT Staffing Phone: +353 1 543 5083 Google Ireland Ltd., Barrow Street, Dublin 4, Ireland Registered in Dublin, Ireland Registration Number: 368047 I think this is interesting even to those who are not looking for a job right now, since it shows the current mind-set regarding Haskell, at a major and leading IT company. Best Regards, Hans van Thiel I would be far from the first to remark that the 'Python Paradox' (http://www.paulgraham.com/pypar.html) has moved on and become the Scala/Haskell Paradox. -- gwern ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Links to darcs.haskel.org in the haskellwiki
On Mon, Feb 8, 2010 at 5:35 PM, Henning Thielemann schlepp...@henning-thielemann.de wrote: Ketil Malde schrieb: Henk-Jan van Tuyl hjgt...@chello.nl writes: There are a lot of links in the haskellwiki that point to projects at darcs.haskel.org; I hope that anyone who moves a project, looks the links up and updates them. An example of a page with several obsolete links is I check my own pages once in a while with Google webmaster tools, which tells me about these things (and provides other useful information as well). Perhaps this is useful for the Haskell wiki as well? Bulk updates in Wikis are not very funny. I have also searched for links to my darcs.haskell.org repositories in HaskellWiki and I hope I have updated them all, which is very cumbersome. It would be cool if there would be a way to access the Wiki contents like a file system, such that I can use 'grep' and friends for such tasks. http://en.wikipedia.org/wiki/Wikipedia:WikipediaFS It was working when I last tried it a year or 3 ago; no idea whether it still does or would work with Hawiki. Also, it's 'on demand' loading. -- gwern ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Anyone up for Google SoC 2010?
On Fri, Feb 5, 2010 at 6:20 AM, Sittampalam, Ganesh ganesh.sittampa...@credit-suisse.com wrote: Gwern Branwen wrote: On Wed, Feb 3, 2010 at 8:14 PM, Henk-Jan van Tuyl hjgt...@chello.nl wrote: On Wed, 03 Feb 2010 23:34:34 +0100, Neil Mitchell ndmitch...@gmail.com wrote: Hi Gwern, Please update: haskell-src-exts - haskell-src **Unknown** This project was an unqualified success. haskell-src-exts is now one of the most commonly used Haskell libraries, achieved the goals in the project proposal, and is an essential piece of Haskell infrastructure. You can see this using Roel van Dijk's reversed dependencies overview [1]: 23 direct and 57 indirect dependencies on haskell-src-exts-1.8.0 Regards, Henk-Jan van Tuyl And how many of those used haskell-src-exts *before* the SoC project? And would have used it regardless? You can't point to a popular project which got a SoC student, and say look at how popular it is - obviously the SoC student was hugely successful. Regardless of that, is there any reason to disregard Neil's summary and not update your page? Ganesh I prefer to wait. haskell-src-exts was popular before, it was popular after. The question is not whether the patches were applied, or whether the mentor told Google it was successful, but whether it was the best possible use of the SoC slot. If features do not get used, then it wasn't a good SoC. If you know 3 or 4 uses of the new haskell-src-exts features in (relatively) major applications like hlint, then I'll concede the point and mark it a success. -- gwern ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Anyone up for Google SoC 2010?
On Fri, Feb 5, 2010 at 3:38 PM, Niklas Broberg niklas.brob...@gmail.com wrote: I'm at a loss as to what criteria is actually used to judge success here. It seems to me a bit like the eternal discussion between basic research and applied research. Just because something (research/library/project) doesn't have an immediate, palpable impact and/or delivers a visible tool, that certainly doesn't imply that it doesn't have merit or won't have as profound an impact on the domain, if more diffuse than a tool (or other palpable deliverable) would. /Niklas There may be an eternal discussion on it, but it seems pretty clear to me which side SoC comes down on: http://code.google.com/soc/ Through Google Summer of Code, accepted student applicants are paired with a mentor or mentors from the participating projects, thus gaining exposure to real-world software development scenarios and the opportunity for employment in areas related to their academic pursuits. In turn, the participating projects are able to more easily identify and bring in new developers. Best of all, more source code is created and released for the use and benefit of all. or http://socghop.appspot.com/document/show/program/google/gsoc2009/faqs#goals # Google Summer of Code has several goals: * Get more open source code created and released for the benefit of all * Inspire young developers to begin participating in open source development * Help open source projects identify and bring in new developers and committers * Provide students the opportunity to do work related to their academic pursuits during the summer (think flip bits, not burgers) * Give students more exposure to real-world software development scenarios (e.g., distributed development, software licensing questions, mailing-list etiquette) -- gwern ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Anyone up for Google SoC 2010?
On Wed, Feb 3, 2010 at 8:14 PM, Henk-Jan van Tuyl hjgt...@chello.nl wrote: On Wed, 03 Feb 2010 23:34:34 +0100, Neil Mitchell ndmitch...@gmail.com wrote: Hi Gwern, Please update: haskell-src-exts - haskell-src **Unknown** This project was an unqualified success. haskell-src-exts is now one of the most commonly used Haskell libraries, achieved the goals in the project proposal, and is an essential piece of Haskell infrastructure. You can see this using Roel van Dijk's reversed dependencies overview [1]: 23 direct and 57 indirect dependencies on haskell-src-exts-1.8.0 Regards, Henk-Jan van Tuyl And how many of those used haskell-src-exts *before* the SoC project? And would have used it regardless? You can't point to a popular project which got a SoC student, and say look at how popular it is - obviously the SoC student was hugely successful. -- gwern ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Failure to load hmatric
On Tue, Feb 2, 2010 at 1:59 PM, d...@patriot.net wrote:
OK, I'm working on matrix stuff in Haskell now (I've been trying to get
the professor to approve that) and when I use cabal install to install
hmatrix, it fails at HUnit with:
---
Configuring HUnit-1.2.2.1...
Preprocessing library HUnit-1.2.2.1...
Preprocessing executables for HUnit-1.2.2.1...
Building HUnit-1.2.2.1...
[1 of 5] Compiling Test.HUnit.Terminal ( Test/HUnit/Terminal.hs,
dist/build/Test/HUnit/Terminal.o )
[2 of 5] Compiling Test.HUnit.Lang ( Test/HUnit/Lang.hs,
dist/build/Test/HUnit/Lang.o )
[3 of 5] Compiling Test.HUnit.Base ( Test/HUnit/Base.hs,
dist/build/Test/HUnit/Base.o )
[4 of 5] Compiling Test.HUnit.Text ( Test/HUnit/Text.hs,
dist/build/Test/HUnit/Text.o )
[5 of 5] Compiling Test.HUnit ( Test/HUnit.hs,
dist/build/Test/HUnit.o )
/usr/bin/ar: creating dist/build/libHSHUnit-1.2.2.1.a
Test/HUnit/Lang.hs:22:1: lexical error at character 'i'
cabal: Error: some packages failed to install:
HUnit-1.2.2.1 failed during the building phase. The exception was:
exit: ExitFailure 1
Short term question: what the heck do I do with this?
Long term question: how can I handle cabal failures of this type without
bothering the list every time?
Dave Barton
University of Toronto
Well, the obvious thing to do is to look at the line causing the
error. The line and surrounding lines are:
---
-- Imports
-- ---
import Data.List (isPrefixOf)
21: #if defined(__GLASGOW_HASKELL__) || defined(__HUGS__)
import Data.Dynamic
import Control.Exception as E
#else
import System.IO.Error (ioeGetErrorString, try)
#endif
---
Line 12 is the first CPP directive in the file; GHC doesn't understand
CPP unless you tell it to. So one could look at the hunit.cabal and
try to figure out why CPP wasn't enabled, or one could add into the
first line of the file
'{-# LANGUAGE CPP #-}'
and work around it.
But you can't start if you don't know what the problem is.
--
gwern
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Re: [Haskell-cafe] Anyone up for Google SoC 2010?
On Tue, Feb 2, 2010 at 5:11 PM, Johan Tibell johan.tib...@gmail.com wrote: On Tue, Feb 2, 2010 at 2:06 PM, Neil Mitchell ndmitch...@gmail.com wrote: I'd also be happy to mentor. Where is the official place to collect project ideas? We used trac previously, are we still using it or are we now on Reddit? Is there a way to prune the reddit list? Some of the projects (like 'text') are already done. Also, voting doesn't work well for reddit as we're still seeing votes from last year. -- Johan You can prune them personally with 'hide', and I suppose the subreddit moderator can delete expired entries. -- gwern ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] HList darcs repo missing?
On Mon, Jan 25, 2010 at 3:47 PM, Jake Wheat jakewheatm...@googlemail.com wrote: Hello all, I was looking for the HList darcs repo at: http://darcs.haskell.org/HList/ but it seems to be missing. Has it been moved somewhere else? Thanks, Jake Wheat It was there as of 15 September 2009 when I sent Oleg my last patch. Maybe some of the server changes since messed around with it? -- gwern ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Broken registration link on hackage trac
On Mon, Jan 18, 2010 at 6:17 PM, Ian Lynagh ig...@earth.li wrote: On Mon, Jan 18, 2010 at 07:35:31PM +, Andy Gimblett wrote: I want to register an account on hackage's trac instance, but the register an account link on the start page: http://hackage.haskell.org/trac/hackage/wiki/WikiStart is broken. Fixed - thanks for the report. Thanks Ian While we're fixing things, has anyone else noticed that the QuickCheck mailing list seems to be broken? -- gwern ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] cabal install vacuum-cairo
On Sun, Jan 17, 2010 at 9:55 AM, Ozgur Akgun ozgurak...@gmail.com wrote: Cafe, I've been trying to install vacuum-cairo using cabal but I couldn't have it installed because of the missing packages cairo, svg and gtkcairo. What should I do to install vacuum-cairo? Thanks for any help in advance, Those packages are provided by http://www.haskell.org/gtk2hs/ cabal-install didn't pull them in because they are too difficult to cabalize hence not on Hackage. -- gwern ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Compilers
On Sat, Nov 29, 2008 at 8:02 PM, John Meacham j...@repetae.net wrote:
On Sat, Nov 29, 2008 at 11:41:03PM +0100, Daniel Fischer wrote:
Great, nothing I don't already have, so download the source tarball, unpack
and
./configure --prefix=$HOME
checking for a BSD-compatible install... /usr/bin/install -c
checking whether build environment is sane... yes
... more configure output ...
checking for drift-ghc... no
configure: error: DrIFT not found get it from
http://repetae.net/computer/haskell/DrIFT/
Huh?
da...@linux:~/jhc/jhc-0.5.20080307 which DrIFT
/home/dafis/.cabal/bin/DrIFT
da...@linux:~/jhc/jhc-0.5.20080307 DrIFT --version
Version DrIFT-2.2.3
Oh golly. I never put DrIFT on cabal, apparently whomever tried to
cabalize it didn't include the ghc driver script, and also appeared to
just drop the documentation from the package altogether. It is things
like that that make it very hard to get behind cabal, why was DrIFT
crippled just so it can be put on cabal? If cabal wasn't powerful enough
to compile DrIFT, and we already had a perfectly good way of compiling
it, why the need to shoehorn it in and cause this problem? sigh.
...
John
Thought I'd mention that
http://hackage.haskell.org/package/DrIFT-cabalized 2.2.3.1 includes a
drift-ghc.hs (compiles to /home/gwern/bin/bin/DrIFT-cabalized-ghc)
which is a clone of the drift-ghc.in shell script you allude to:
import Data.List (isInfixOf)
import System.Cmd (rawSystem)
import System.Environment (getArgs)
import System.Exit (ExitCode(ExitSuccess))
import Paths_DrIFT_cabalized (getBinDir)
main :: IO ExitCode
main = do args - getArgs
case args of
(a:b:c:[]) - conditional a b c
_ - error This is a driver script allowing DrIFT to be
used seamlessly with ghc.\n \
\ in order to use it, pass '-pgmF drift-ghc -F'
to ghc when compiling your programs.
conditional :: FilePath - FilePath - FilePath - IO ExitCode
conditional orgnl inf outf = do prefix - getBinDir
infile - readFile inf
if {-! `isInfixOf` infile then do
putStrLn (prefix ++ DriFT-cabalized ++
inf ++ -o ++ outf)
rawSystem inf [-o, outf]
else do writeFile outf ({-# LINE 1
\ ++ orgnl ++ #-})
readFile inf = appendFile outf
return ExitSuccess
{- GHC docs say: -pgmF cmd
Use cmd as the pre-processor (with -F only).
Use -pgmF cmd to select the program to use as the preprocessor.
When invoked, the cmd pre-processor is given at least three arguments
on its command-line:
1. the first argument is the name of the original source file,
2. the second is the name of the file holding the input
3. third is the name of the file where cmd should write its output to. -}
John: I would appreciate you pointing out if I have made a mistake
anywhere in that and not actually replicated the functionality of the
shell script. (I think I have, but I didn't really understand what the
first echo was supposed to do and just copied its functionality.)
--
gwern
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Re: [Haskell-cafe] Design question, HTML for GUIs?
2010/1/10 Günther Schmidt gue.schm...@web.de: Hi everyone, as probably most people I find the GUI part of any application to be the hardest part. It just occurred to me that I *could* write my wxHaskell desktop application as a web app too. When the app starts, a haskell web server start listening on localhost port 8080 for example and I fire up a browser to page localhost:8080 without the user actually knowing too much about it. Is that a totally stupid idea? Which haskell web servers would make good candidates? No; Happstack. See Gitit for an example - it is a wiki, but people use it locally all the time, such as myself or Don Stewart. -- gwern ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ghc -e
On Wed, Jan 6, 2010 at 7:23 PM, Tony Morris tonymor...@gmail.com wrote: ghc -e import Control.Monad; forM [[1,2,3]] reverse As of 6.10.2, the bug whereby the GHC API lets you use functions from anywhere just by naming them (Java-style) has not been fixed: $ ghc -e Control.Monad.forM [[1,2,3]] reverse package flags have changed, resetting and loading new packages... interactive:1:25: Warning: Defaulting the following constraint(s) to type `Integer' `Num t' arising from the literal `3' at interactive:1:25 In the expression: 3 In the expression: [1, 2, 3] In the first argument of `forM', namely `[[1, 2, 3]]' interactive:1:25: Warning: Defaulting the following constraint(s) to type `Integer' `Num t' arising from the literal `3' at interactive:1:25 In the expression: 3 In the expression: [1, 2, 3] In the first argument of `forM', namely `[[1, 2, 3]]' [[3],[2],[1]] it :: [[Integer]] (0.01 secs, 1710984 bytes) -- gwern ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ghc -e
On Wed, Jan 6, 2010 at 7:35 PM, Tony Morris tonymor...@gmail.com wrote: Gwern Branwen wrote: On Wed, Jan 6, 2010 at 7:23 PM, Tony Morris tonymor...@gmail.com wrote: ghc -e import Control.Monad; forM [[1,2,3]] reverse As of 6.10.2, the bug whereby the GHC API lets you use functions from anywhere just by naming them (Java-style) has not been fixed: $ ghc -e Control.Monad.forM [[1,2,3]] reverse package flags have changed, resetting and loading new packages... interactive:1:25: Warning: Defaulting the following constraint(s) to type `Integer' `Num t' arising from the literal `3' at interactive:1:25 In the expression: 3 In the expression: [1, 2, 3] In the first argument of `forM', namely `[[1, 2, 3]]' interactive:1:25: Warning: Defaulting the following constraint(s) to type `Integer' `Num t' arising from the literal `3' at interactive:1:25 In the expression: 3 In the expression: [1, 2, 3] In the first argument of `forM', namely `[[1, 2, 3]]' [[3],[2],[1]] it :: [[Integer]] (0.01 secs, 1710984 bytes) I see the same on GHC 6.10.4. $ ghc -e Control.Monad.forM [[1,2,3]] reverse [[3],[2],[1]] What would it be fixed to? What is wrong with how it is? Presumably one then have to use some sort of flag to ask for Control.Monad specifically to be visible. What's wrong with it is that this is not merely GHCi behavior, this is universal GHC API behavior and wildly insecure: http://hackage.haskell.org/trac/ghc/ticket/2452 -- gwern ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
