RE: [Haskell-cafe] Re: Properties of optimizer rule application?
| Ok, this was a bad example. Try this one: |project . project . foo | with the rules |project (project x) = project x |project (foo x) = projectFoo x | | Both rules can be applied to the expression, but you get one fusion more, | if you use the first one first. Let me guess, in order to solve that, I | should restrict the first rule to an earlier phase than the second rule. As you point out, this set of rules is not confluent: project (project foo) can reduce to --- project (projectFoo x) or to --- projectFoo x depending on the order of application. The conventional solution is not to apply the rules very carefully (which is extremely hard in general), but rather to complete the rules, by adding project (projectFoo x) = projectFoo x Now it doesn't matter which order you apply them in. You can do this by hand, although it'd be quite a nice thing to automate it in GHC. | To give a precise example: If I have a sequence of 'map's | map f0 . map f1 . ... . map fn | then there is some length where this is no longer collapsed to a single | 'map'? (a) GHC tries to do as much as possible in a single iteration of the simplifer; I think it uses an outermost-first strategy for this. (b) For each phase it runs the simplifier until nothing changes, or a maximum of N times, where N is settable by a command-line-flag -fmax-simplifier-iterations. After N it stops running that phase, even if the simplification has not terminated. | However then I wonder, how it is possible to make the compiler to | go into an infinite loop by the rule | |loop forall x,y. f x y = f y x Yes, it's possible. Remember (a) does as much as possible, which in your rule means rather a lot. In this thread Roman and I have described stuff that isn't in the manual. Henning, would you feel like elaborating the Wiki page http://haskell.org/haskellwiki/GHC/Using_rules (which already has a lot of info) to reflect what you've learned? That way it's preserved for others. thanks Simon ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: announcing darcs 2.0.0pre2
David Roundy wrote: On Thu, Jan 03, 2008 at 11:11:40AM +, Simon Marlow wrote: Anyhow, could you retry this test with the above change in methodology, and let me know if (a) the pull is still slow the first time and (b) if it's much faster the second time (after the reverse unpull/pull)? I think I've done it in both directions now, and it got faster, but still much slower than darcs1: $ time darcs2 unpull --from-tag 2007-09-25 -a Finished unpulling. 58.68s real 50.64s user 6.36s system 97% darcs2 unpull --from-tag 2007-09-25 -a $ time darcs2 pull -a ../ghc-darcs2 Pulling from ../ghc-darcs2... Finished pulling and applying. 53.28s real 44.62s user 7.10s system 97% darcs2 pull -a ../ghc-darcs2 This is still an order of magnitude slower than darcs1 for the same operation. (these times are now on the local filesystem, BTW) I've recently found the problem leading to this slowdown (I believe) and get about an order-of-magnitude improvement in the speed of a pull of 400 patches in the ghc repository. It turned out to be an issue that scaled with the size (width) of the repository, not with the number of patches (which had been the obvious suspect), which was causing trouble when applying to the pristine cache. At this point, darcs-2 outperforms darcs-1 on most tests that I've tried, so it'd be a good time to find some more performance problems, if you can... and I don't doubt that there are more out there. Certainly a lot faster, nice work! Though it's still not as fast as darcs-1 here. New figures: $ time darcs2 unpull --from-tag 2007-09-25 -a Finished unpulling. 18.83s real 15.27s user 1.53s system 89% darcs2 unpull --from-tag 2007-09-25 -a $ time darcs2 pull ../ghc-darcs2-other -a Finished pulling and applying. 10.38s real 7.69s user 1.50s system 88% darcs2 pull ../ghc-darcs2-other - I repeated the darcs-1 timings for comparison: $ time darcs unpull --from-tag 2007-09-25 -a Finished unpulling. 8.04s real 7.14s user 0.90s system 99% darcs unpull --from-tag 2007-09-25 -a $ time darcs pull ~/ghc-HEAD -a Finished pulling and applying. 7.90s real 4.90s user 0.98s system 74% darcs pull ~/ghc-HEAD -a In this case darcs-1 is pulling more patches (530 vs. 400), because I'm using the latest GHC HEAD repo. Also the darcs-1 repository being pulled from is on a different, NFS mounted, filesystem, whereas the darcs-2 timings were made using repos on the same local filesystem. In all cases I tried things a few times to let caches etc. fill up. Can you repeat these? Cheers, Simon ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] First go at reactive programming
Hi, Below is a version that was aimed at getting rid of the (Handle,IO (Request a)) tuples and as a result made it easier to remove the IO monad from some types, but I don't think it removed it completely from any methods. module Main where import Control.Applicative import Control.Concurrent import Control.Monad import Data.Reactive import Network.BSD import Network.HTTP import Network import System.IO import Text.XHtml.Strict type RequestHandler = Request - Response main = runHttpServer helloWorldHandler helloWorldHandler :: RequestHandler helloWorldHandler = Response (2,0,0) [] . prettyHtml . helloWorldDoc helloWorldDoc :: Request - Html helloWorldDoc rq = header thetitle Hello World +++ body(h1 Hello World +++ p show rq) runHttpServer :: RequestHandler - IO a runHttpServer r = socketServer = runE . fmap (handleConnection r) socketServer :: IO (Event Handle) socketServer = withSocketsDo $ do (e,snk) - mkEventShow Server sock- listenOn (PortNumber 8080) forkIO $ forever $ acceptConnection sock $ snk return e handleConnection :: Handle - RequestHandler - IO () handleConnection h r = handleToRequest h = responseSend h . runRequestHandler r handleToRequest :: Handle - IO (Result Request) handleToRequest = receiveHTTP runRequestHandler :: RequestHandler - Result Request - Result Response runRequestHandler r rq = rq `bindE` (Right . r) responseSend :: Handle - Result Response - IO () responseSend h rsp = either print (respondHTTP h) rsp close h acceptConnection :: Socket - (Handle - IO ()) - IO ThreadId acceptConnection s k = accept s = \(h,_,_) - forkIO $ k h instance Stream Handle where readLine h = hGetLine h = \l - return $ Right $ l ++ \n readBlock h n = replicateM n (hGetChar h) = return . Right writeBlock h s = mapM_ (hPutChar h) s = return . Right close = hClose ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] libmpd-haskell RFC
* Ben Sinclair [EMAIL PROTECTED] [2008-01-16 22:02:40+1100] If anybody has already used libmpd-haskell (the darcs repo version) or would like to look over it I would appreciate their comments. Thanks, Ben http://turing.une.edu.au/~bsinclai/code/libmpd-haskell/ I'd like to use it in xmonad extension to control MPD, but since all extensions live in one package (XMonadContrib), adding new dependencies is discouraged, so I chose ad-hoc solution using netcat. -- Roman I. Cheplyaka :: http://ro-che.info/ ...being in love is totally punk rock... signature.asc Description: Digital signature ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] ghc6.8: hiding uninstalled package?
This might seem like a silly question, but what's the reasoning behind the following behaviour? % ghc-pkg list dataenc /usr/lib/ghc-6.8.2/package.conf: % ghc --make -hide-package dataenc -isrc UT.hs ghc-6.8.2: unknown package: dataenc Hiding an uninstalled package doesn't seem to warrant failing compilation! /M ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Filter by several predicates at once
Are the functions passall, passany :: [a - Bool] - a - Bool passall ps v = and $ map ($v) ps passany ps v = or $ map ($v) ps or something similar defined anywhere? Such that one can write filter (passany tests) [0..10] filter (passall tests) [0..10] where tests = [5, odd] Or is there a better way of filtering by several predicates for each value without using filter p3 . filter p2 . filter p1 or filter (\v - p1 v p2 v p3 v) vs Cheers, D -- Dougal Stanton [EMAIL PROTECTED] // http://www.dougalstanton.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Filter by several predicates at once
Hi passall, passany :: [a - Bool] - a - Bool passall ps v = and $ map ($v) ps passany ps v = or $ map ($v) ps or something similar defined anywhere? Such that one can write Don't think so. One thing I have often wanted is something like: or1 a b x = a x || b x or2 a b x y = a x y || b x y Then you can do: filter ((5) `or1` odd) [0..10] filter ((5) `and1` odd) [0..10] You can imagine that or1 could get a symbol such as ||#, and or2 could perhaps be ||## (if # wasn't already really overloaded) Thanks Neil ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Compiling Blobs
Peter Verswyvelen wrote: I'm trying to build http://www.cs.york.ac.uk/fp/darcs/Blobs using GHC 6.8.2. It looks like a good Haskell program to learn from. So far I managed to modify the source code so it makes use of the new HaXML libraries, and after a lot of hacking I could build and link to wxHaskell, but my app crashes (I do get a window however, woohoo) Maybe someone else managed already? Thanks, Peter ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe Hi Peter, I have Blobs compiling and running in my machine. Its an Kubuntu Gutsy with GHC 6.6.1 and HaXml 1.19.SOMETHING (I'm using a repository version but not yet the current one) This implies some minor changes that I've as local patches, that I can send to you as soon as I find how to get a file per patch from the repository. The big issue is always to be able to get wxHaskell compiled and working properly. I'm currently using a recent (1 or 2 weeks old) version of wxHaskell from its official repository (darcs get http://darcs.haskell.org/wxhaskell) and wxGTK 2.6.3 You can find more information in INblobs (INblobs is done on top of Bblobs) webpage : http://haskell.di.uminho.pt/jmvilaca/INblobs/ or in the wxHaskell mailing list [EMAIL PROTECTED] What versions of wxWidgets are you using and in which platform? best Miguel Vilaca ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Filter by several predicates at once
Neil Mitchell wrote: Hi passall, passany :: [a - Bool] - a - Bool passall ps v = and $ map ($v) ps passany ps v = or $ map ($v) ps or something similar defined anywhere? Such that one can write nearly; using Prelude: passall ps v = all ($v) ps passany ps v = any ($v) ps One thing I have often wanted is something like: or1 a b x = a x || b x or2 a b x y = a x y || b x y yep, there's the idea of putting Bools in a typeclass that allows you to (||) functions-returning-Bool-class-instance for example, which I haven't used much but seems like a good idea (though potentially confusing, especially if the Prelude-Bool-specific names are reused) ~Isaac ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Filter by several predicates at once
On 17/01/2008, Stuart Cook [EMAIL PROTECTED] wrote: On Jan 18, 2008 1:46 AM, Isaac Dupree [EMAIL PROTECTED] wrote: nearly; using Prelude: passall ps v = all ($v) ps passany ps v = any ($v) ps Yes, thanks Isaac. That should have been obvious, argh... passall = swing all passany = swing any Whether that's any better than the pointwise version is up to you. I think in this case I will use the explicit version, because I wouldn't remember how swing worked. What is the motivation for the name? ;-) (Do I want to hear the answer...?) D -- Dougal Stanton [EMAIL PROTECTED] // http://www.dougalstanton.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Haskell and GUI
Am Dienstag, 15. Januar 2008 20:42 schrieb Conal Elliott: If you can get wxHaskell installed working, you could try Phooey and/or TV. Both are described on the Haskell wiki and available via darcs and Hackage. And they have the interesting property of being a functional approach to GUI programming (similar to FranTk). Most of the other Haskell GUI toolkits are imperative in nature. And now my shameless plug: If you can get Gtk2Hs installed and working, you could try Grapefruit which is also a functional library. In addition to GUIs, it also supports animated graphics. At the moment, it’s main downside is that it supports only a small set of widgets (buttons, labels, edit fields and boxes). See http://haskell.org/haskellwiki/Grapefruit. Best wishes, Wolfgang ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Hamming's Problem
Hi, In exercise 2 of http://www.walenz.org/Dijkstra/page0145.html we need to write a function that holds (1)The value 1 is in the sequence (2)If x and y are in the sequence, so is f(x,y), where f has the properties a. f(x,y) x b. (y1 y2) = (f(x,y1)f(x,y2)) This is a solution for this problem, but an inefficient one hammingff :: [Integer] hammingff = 1 : merge [ h x y | x - hammingff, y - hammingff ] [ h x y | y - hammingff, x - hammingff ] h x y = 2*x+3*y merge :: (Ord a) = [a] - [a] - [a] merge [] xs = xs merge ys [] = ys merge (x:xs) (y:ys) = case compare x y of LT - x : merge xs (y:ys) GT - y : merge (x:xs) ys EQ - x : merge xs ys anybody has a better solution?. Thanks Jose ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Filter by several predicates at once
On Jan 18, 2008 1:46 AM, Isaac Dupree [EMAIL PROTECTED] wrote: Neil Mitchell wrote: Hi passall, passany :: [a - Bool] - a - Bool passall ps v = and $ map ($v) ps passany ps v = or $ map ($v) ps or something similar defined anywhere? Such that one can write nearly; using Prelude: passall ps v = all ($v) ps passany ps v = any ($v) ps See also http://haskell.org/haskellwiki/Pointfree#Swing, which would let you define passall = swing all passany = swing any Whether that's any better than the pointwise version is up to you. Stuart ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] libmpd-haskell RFC
roma: * Ben Sinclair [EMAIL PROTECTED] [2008-01-16 22:02:40+1100] If anybody has already used libmpd-haskell (the darcs repo version) or would like to look over it I would appreciate their comments. Thanks, Ben http://turing.une.edu.au/~bsinclai/code/libmpd-haskell/ I'd like to use it in xmonad extension to control MPD, but since all extensions live in one package (XMonadContrib), adding new dependencies is discouraged, so I chose ad-hoc solution using netcat. We could have multiple extension packages (i.e. xmonadcontrib-network) for things that touch the network. -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Data constructors versus types
Richard A. O'Keefe [EMAIL PROTECTED] wrote: I have no idea what get/cc might be, unless it is a mistake for call/cc, but that's Scheme, not Lisp. Erm... yes. I guess it's the part of call/cc that gets the continuation before calling it. Actually, I shouldn't be talking about stuff that was used before I was even planned... -- (c) this sig last receiving data processing entity. Inspect headers for past copyright information. All rights reserved. Unauthorised copying, hiring, renting, public performance and/or broadcasting of this signature prohibited. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Data constructors versus types
Anton van Straaten [EMAIL PROTECTED] wrote: [EMAIL PROTECTED] wrote: On 2008.01.17 00:58:19 +0100, [EMAIL PROTECTED] scribbled 0.9K characters: Achim Schneider writes: Lisp is actually not really meant to be compiled, but interpreted. ... Would you mind stopping to spread dubious truths? ... I don't think it's a dubious truth. It's about as accurate as saying Television is actually not really meant to be color, but black and white. Yes, that about fits... the chroma data still has only half the resolution of luminosity. In fact, it wasn't even meant to be a programming language, just a calculus. But still, I should have written was meant not is meant. -- (c) this sig last receiving data processing entity. Inspect headers for past copyright information. All rights reserved. Unauthorised copying, hiring, renting, public performance and/or broadcasting of this signature prohibited. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ghc6.8: hiding uninstalled package?
Magnus Therning wrote: This might seem like a silly question, but what's the reasoning behind the following behaviour? % ghc-pkg list dataenc /usr/lib/ghc-6.8.2/package.conf: % ghc --make -hide-package dataenc -isrc UT.hs ghc-6.8.2 : unknown package: dataenc Hiding an uninstalled package doesn't seem to warrant failing compilation! I cannot find it, therefore I cannot hide it? XD The following is fairly widely accepted behaviour: $ rm phd-thsies rm: cannot remove `phd-thsies': No such file or directory If a file is absent and you want it absent, is that an error? (Now you might get into a long thread debating whether deletion is analogous to hiding...) If I want to hide or delete something, and the computer can't find that something, it may be because I have a typo. If the computer remains silent about it, I fail to hide or delete the true thing. I want to delete phd-thesis, but I typed phd-thsies, and I appreciate the error report. If I fail to delete phd-thesis, at worst more people read it and be enlightened :) but if I fail to hide a package and I don't know about it, the ensuing problems will be much more mysterious. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] libmpd-haskell RFC
* Don Stewart [EMAIL PROTECTED] [2008-01-17 08:56:14-0800] roma: * Ben Sinclair [EMAIL PROTECTED] [2008-01-16 22:02:40+1100] If anybody has already used libmpd-haskell (the darcs repo version) or would like to look over it I would appreciate their comments. Thanks, Ben http://turing.une.edu.au/~bsinclai/code/libmpd-haskell/ I'd like to use it in xmonad extension to control MPD, but since all extensions live in one package (XMonadContrib), adding new dependencies is discouraged, so I chose ad-hoc solution using netcat. We could have multiple extension packages (i.e. xmonadcontrib-network) for things that touch the network. It doesn't really matter -- I hardly imagine amarok user who would agree to fetchbuild libmpd-haskell in order to use some other network-related extension. -- Roman I. Cheplyaka :: http://ro-che.info/ ...being in love is totally punk rock... signature.asc Description: Digital signature ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Hamming's Problem
The author of Pugs (Perl6 implemented in Haskell) gives a nice solution to the problem of generating the Hamming numbers in the following interview: http://www.perl.com/pub/a/2005/09/08/autrijus-tang.html?page=last ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Compiling Blobs
Sorry guys, this email also got in my personal email box, I did not mention to send this to the cafe. And with this message this is double spam, duh. On Thu, 2008-01-17 at 20:10 +0100, Peter Verswyvelen wrote: Hi Miguel! Thanks for the reply! Yes, I also took the latest darcs version of wxHaskell, HaXml 1.19.2, and polyparse. I had to do some minor tweaks to the Blobs source code (mainly Text.Parse stuff, no big deal really). I used wxGTK 2.6.4, --with-opengl and --disable-sharing (otherwise I got link errors when linking Blobs). However I'm using GHC 6.8.2 on Fedora 8. BTW what do you think is the best distro for doing Haskell development? Now I just switched from Windows to Linux, so this is all very very new to me. However I do like the Linux way of settings things up, so I'm planning to dig a bit deeper in the Linux world. Not easy because I know a lot about Windows development, so giving that up is hard. I'll take a look at the website you mentioned. The fact to you have it running gives me confidance it is possible :) Cheers, Peter On Thu, 2008-01-17 at 14:51 +, Miguel Vilaça wrote: Peter Verswyvelen wrote: I'm trying to build http://www.cs.york.ac.uk/fp/darcs/Blobs using GHC 6.8.2. It looks like a good Haskell program to learn from. So far I managed to modify the source code so it makes use of the new HaXML libraries, and after a lot of hacking I could build and link to wxHaskell, but my app crashes (I do get a window however, woohoo) Maybe someone else managed already? Thanks, Peter ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe Hi Peter, I have Blobs compiling and running in my machine. Its an Kubuntu Gutsy with GHC 6.6.1 and HaXml 1.19.SOMETHING (I'm using a repository version but not yet the current one) This implies some minor changes that I've as local patches, that I can send to you as soon as I find how to get a file per patch from the repository. The big issue is always to be able to get wxHaskell compiled and working properly. I'm currently using a recent (1 or 2 weeks old) version of wxHaskell from its official repository (darcs get http://darcs.haskell.org/wxhaskell) and wxGTK 2.6.3 You can find more information in INblobs (INblobs is done on top of Bblobs) webpage : http://haskell.di.uminho.pt/jmvilaca/INblobs/ or in the wxHaskell mailing list [EMAIL PROTECTED] What versions of wxWidgets are you using and in which platform? best Miguel Vilaca ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Data constructors versus types
It's about as accurate as saying Television is actually not really meant to be color, but black and white. Funny, but that is actually correct, since both NTSC and PAL did a lot of tricks to carry color information using the same infrastructure as black and white TVs :) Of course that will soon be over when we all go digital, then we have jaggies and blockies because of over-compression :) Okay, ff topic. Cheers, Peter ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: ANN: A triple of new packages for talking tothe outside world
Adam Langley agl at imperialviolet.org writes: BitGet is just an API RFC at the moment, so I'm just describing it here - not trying to justify it. In BitGet there's getAsWord[8|16|32|64] which take a number of bits ($n$) and returns the next $n$ bits in the bottom of a Word$x$. Thus, getAsWord8 is what you call getBits and, if you had a 48 bit number, you could use getAsWord64 and the bottom 48-bits of the resulting Word64 would be what you want. Equally, asking for more than $x$ bits when calling getAsWord$x$ is a mistake, however I don't check for it in the interest of speed. There are also get[Left|Right]ByteString which return the next $n$ bits in a ByteString of Word8's. The padding is either at the end of the last byte (left aligned) or at the beginning of the first byte (right aligned). Ok so I should be doing something like this. I'm not clear what happens if you are reading from a socket and not all the input has arrived but I'll think about that over the weekend. Another thought: could e.g. getRightByteString be in the IO monad and then I don't have to run the Get(?) monad? Or is that a really stupid question? Dominic. import qualified Data.ByteString as B import Data.Word import IO import qualified Data.Binary.Strict.BitGet as BG test = do h - openFile foobarbaz ReadMode b - B.hGetContents h let ebms = test2 b case ebms of Left s- return s Right bms - return (concat ((map (show . B.unpack) bms))) test1 = do bm1 - BG.getRightByteString 2 bm2 - BG.getRightByteString 2 return [bm1,bm2] test2 bs = BG.runBitGet bs test1 ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Compiling Blobs
Hi Miguel! Thanks for the reply! Yes, I also took the latest darcs version of wxHaskell, HaXml 1.19.2, and polyparse. I had to do some minor tweaks to the Blobs source code (mainly Text.Parse stuff, no big deal really). I used wxGTK 2.6.4, --with-opengl and --disable-sharing (otherwise I got link errors when linking Blobs). However I'm using GHC 6.8.2 on Fedora 8. BTW what do you think is the best distro for doing Haskell development? Now I just switched from Windows to Linux, so this is all very very new to me. However I do like the Linux way of settings things up, so I'm planning to dig a bit deeper in the Linux world. Not easy because I know a lot about Windows development, so giving that up is hard. I'll take a look at the website you mentioned. The fact to you have it running gives me confidance it is possible :) Cheers, Peter On Thu, 2008-01-17 at 14:51 +, Miguel Vilaça wrote: Peter Verswyvelen wrote: I'm trying to build http://www.cs.york.ac.uk/fp/darcs/Blobs using GHC 6.8.2. It looks like a good Haskell program to learn from. So far I managed to modify the source code so it makes use of the new HaXML libraries, and after a lot of hacking I could build and link to wxHaskell, but my app crashes (I do get a window however, woohoo) Maybe someone else managed already? Thanks, Peter ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe Hi Peter, I have Blobs compiling and running in my machine. Its an Kubuntu Gutsy with GHC 6.6.1 and HaXml 1.19.SOMETHING (I'm using a repository version but not yet the current one) This implies some minor changes that I've as local patches, that I can send to you as soon as I find how to get a file per patch from the repository. The big issue is always to be able to get wxHaskell compiled and working properly. I'm currently using a recent (1 or 2 weeks old) version of wxHaskell from its official repository (darcs get http://darcs.haskell.org/wxhaskell) and wxGTK 2.6.3 You can find more information in INblobs (INblobs is done on top of Bblobs) webpage : http://haskell.di.uminho.pt/jmvilaca/INblobs/ or in the wxHaskell mailing list [EMAIL PROTECTED] What versions of wxWidgets are you using and in which platform? best Miguel Vilaca ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] libmpd-haskell RFC
A comment on documentation. I find it very frustrating when libraries are described as an interface to X, where X is often an acronym that has multiple definitions on the web. Lots of clicking got me to 'Music Player Demon', but no further description or links. Just a little more information, say in a top-level README and/or the Haddock docs would be greatly appreciated. 2008/1/16 Ben Sinclair [EMAIL PROTECTED]: Hello all, If anybody has already used libmpd-haskell (the darcs repo version) or would like to look over it I would appreciate their comments. Thanks, Ben http://turing.une.edu.au/~bsinclai/code/libmpd-haskell/http://turing.une.edu.au/%7Ebsinclai/code/libmpd-haskell/ -BEGIN PGP SIGNATURE- Version: GnuPG v1.4.6 (GNU/Linux) iD8DBQFHjeRPDo+byWtWM/kRApQhAJ9eMVQR+Bd5hgmsXSF9rRvVCS8ZxACg15rl FuRALK8V7ArBSxR9FvTYUr4= =d97o -END PGP SIGNATURE- ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ghc6.8: hiding uninstalled package?
On 1/17/08, Albert Y. C. Lai [EMAIL PROTECTED] wrote: Magnus Therning wrote: This might seem like a silly question, but what's the reasoning behind the following behaviour? % ghc-pkg list dataenc /usr/lib/ghc-6.8.2/package.conf: % ghc --make -hide-package dataenc -isrc UT.hs ghc-6.8.2 : unknown package: dataenc Hiding an uninstalled package doesn't seem to warrant failing compilation! I cannot find it, therefore I cannot hide it? XD The following is fairly widely accepted behaviour: $ rm phd-thsies rm: cannot remove `phd-thsies': No such file or directory If a file is absent and you want it absent, is that an error? (Now you might get into a long thread debating whether deletion is analogous to hiding...) If I want to hide or delete something, and the computer can't find that something, it may be because I have a typo. If the computer remains silent about it, I fail to hide or delete the true thing. I want to delete phd-thesis, but I typed phd-thsies, and I appreciate the error report. If I fail to delete phd-thesis, at worst more people read it and be enlightened :) but if I fail to hide a package and I don't know about it, the ensuing problems will be much more mysterious. Fair enough. I stumbled on this behaviour because I was writing a makefile for my unit/quickcheck tests. I need to make sure that the correct module is used, hence I need to hide it if it's installed. I ended up with the following in order to work around the issue: ifeq (,$(shell ghc-pkg list dataenc | grep dataenc)) GHCOPTS = -fhpc -isrc else GHCOPTS = -fhpc -hide-package dataenc -isrc endif % : %.hs ghc --make $(GHCOPTS) $ Is there a better way to do it? /M ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re[2]: [Haskell-cafe] Filter by several predicates at once
Hello Isaac, Thursday, January 17, 2008, 5:46:20 PM, you wrote: yep, there's the idea of putting Bools in a typeclass that allows you to (||) functions-returning-Bool-class-instance for example, which I haven't used much but seems like a good idea (though potentially confusing, especially if the Prelude-Bool-specific names are reused) -- Datatypes having default values classDefaults a where defaultValue :: a instance Defaults () where defaultValue = () instance Defaults Bool where defaultValue = False instance Defaults [a]where defaultValue = [] instance Defaults (a-a) where defaultValue = id instance Defaults (Maybe a)where defaultValue = Nothing instance Defaults (a-IO a)where defaultValue = return instance Defaults a = Defaults (IO a) where defaultValue = return defaultValue instance Num a = Defaults a where defaultValue = 0 -- Datatypes that can be checked for default value classTestDefaultValue awhere isDefaultValue :: a - Bool instance TestDefaultValue Bool where isDefaultValue = not instance TestDefaultValue [a] where isDefaultValue = null instance Num a = TestDefaultValue a where isDefaultValue = (==0) infixr 3 infixr 2 ||| a ||| b | isDefaultValue a = b | otherwise= a a b | isDefaultValue a = defaultValue | otherwise= b my code contains countless examples of using these funcs: 1. here it is used to conditionally include options in cmdline: [rar, x, arcname]++ (isAddDir [-ad])++ (arcdir files [-ap++arcdir])++... 2. here it is used to get list of files where current directory may be specified as : files - dirList (dirName ||| .) 3. here it is used to show file basename or full path if basename is empty: putStr (takeBaseName file ||| file) 4. here it's used for conditional code execution: do opt_debug command testMalloc ... 5. here it is used to additionally print amount of bad sectors if it's non-zero: putStrLn$ show recoverable_sectors++ recoverable errors ++ (bad_sectors and ++show bad_sectors++ bad sectors) 6. here it's used to create tempfile in current directory unless temporary directory was explicitly specified in --tempdir option let filename = (opt_tempdir command ||| .) / $$temp$$ 7. here it is use to apply additional reorder step to sorted list only if --reorder option was specified sorted_diskfiles - (opt_reorder command reorder) (sort_files command diskfiles) (reorder has type [String] - IO [String]) -- Best regards, Bulatmailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Data constructors versus types
Achim Schneider continues to comment the Lisp history: In fact, it wasn't even meant to be a programming language, just a calculus. There is comprehensive German article (in English), by Herbert Stoyan, on this historical issue: http://www8.informatik.uni-erlangen.de/html/lisp/histlit1.html Stoyan reminds a - currently - not so obvious truth, that something like functional paradigmatics was not so popular at that time, the second half of fifties, beginning of sixties. People reasoned rather in terms of algorithms, and McCarthy was no exception. Let's cite Stoyan: To come back to functional programming, it is an important fact that McCarthy as mathematician was familiar with some formal mathematical languages but did not have a deep, intimate understanding of all their details. McCarthy himself has stressed this fact (23). His aim was to use the mathematical formalismus as languages and not as calculi. This is the root of the historical fact that he never took the Lambda-Calculus conversion rules as a sound basis for LISP implementation. So, I believe it is not so briliant an idea to confound the Church calculus with Lisp! We have also the text of the Master himself, available on-line: http://www-formal.stanford.edu/jmc/history/lisp/lisp.html The chapter on the prehistory: http://www-formal.stanford.edu/jmc/history/lisp/node2.html#SECTION000200 00 begins: My desire for an algebraic list processing language for artificial intelligence work on the IBM 704 computer arose in the summer of 1956 during the Dartmouth Summer Research Project on Artificial Intelligence which was the first organized study of AI. During this meeting, Newell, Shaw and Simon described IPL 2, a list processing language for Rand Corporation's JOHNNIAC... So, sorry, but McCarthy since the very beginning thought about making a usable computer language, not a calculus. When discussing the evolution of FLPL, the *third* point mentions Church for the first time: c. To use functions as arguments, one needs a notation for functions, and it seemed natural to use the -notation of Church (1941). I didn't understand the rest of his book, so I wasn't tempted to try to implement his more general mechanism for defining functions. Church used higher order functionals instead of using conditional expressions. ... See also the article of Paul Graham: http://lib.store.yahoo.net/lib/paulgraham/jmc.ps === Before somebody once more accuses me of pedantry, or says publicly here that I am aggressive towards people: You know that spreading half-truths, and also plain rubbish on Internet is extremely easy. Wherever you look, you find plenty of occasions to err, it suffices to put yourself in a mode of a dead person from the movie The sixth sense of M. Night Shyamalan, with Bruce Willis, and Haley Joel Osment. The boy says to the other main personage (unaware of his own condition) that dead people see only what they WANT to see... And somehow the false information spreads easier than the true one. THIS list, which, independently of the freedom to chat about anything, is still targeted at serious comp. sci. problems, and I think that the fact that somebody is young and inexperienced, is not a justification to make false claims, just because this and that had XXX years less than myself in order to read some easily available texts. Of course, anybody may say dubious truths, I am ashamed of myself, but from time to time I explode. Sorry about this. Jerzy Karczmarczuk ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: ANN: A triple of new packages for talking tothe outside world
On Jan 17, 2008 11:05 AM, Dominic Steinitz [EMAIL PROTECTED] wrote: I'm not clear what happens if you are reading from a socket and not all the input has arrived but I'll think about that over the weekend. At the moment, BitGet deals with strict ByteStrings only. One could use it within a standard Get monad by getting a strict ByteString from the lazy input. I believe that lazy ByteStrings got fixed a while back so that reading from a socket doesn't block reading a whole block. (i.e. if you trickle data, byte by byte, to a socket a lazy ByteString should return a spine of 1 byte strict ByteStrings.) A fully lazy BitGet would also be possible, of course, I've just not written it yet ;) Adam Langley agl at imperialviolet.org writes: Another thought: could e.g. getRightByteString be in the IO monad and then I don't have to run the Get(?) monad? Or is that a really stupid question? If it were in the IO monad, I guess that you're suggesting that it read from a handle? If that were the case, the remainder of the last byte would have to be discarded because one can only read whole bytes from a Handle and there's no mechanism for pushing back into it. It's certainly possible to do, but I think a quick wrapper around a BitGet would be the way to do it. If it's particually desirable I can add it, although I'll admit that it seems a bit odd and I'm wondering what your use case is. Cheers AGL -- Adam Langley [EMAIL PROTECTED] http://www.imperialviolet.org 650-283-9641 ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Compiling Blobs
Peter Verswyvelen wrote: However I'm using GHC 6.8.2 on Fedora 8. BTW what do you think is the best distro for doing Haskell development? they all suck if you want to be able to try/use the latest stuff, in my experience; just install a GHC and cabal stuff in your home directory (you can install more than one GHC-version there if you want to test things with multiple versions...). There's a semi-good reason for this: distros don't like to package broken things, and usually something breaks with each different version of GHC, but not necessarily something you're relying on, and as you're doing Haskell development you may be able to help fix it. so that is, you compile (configure) things with --prefix=$HOME (or --prefix=$HOME/unix or so if you don't like your home-directory being cluttered with names like bin, lib etc.). and when using cabal you also, if it's a system-wide-installed ghc, need to give --user when configuring. And then you add whatever-you-put-for-prefix/bin to your path, e.g. in ~/.bashrc adding PATH=$HOME/bin:$PATH so that the programs (ghc, happy, alex, xmonad, whatever) will be found if you want to run them. Did I leave anything important out? now, there might be a distro system that actually worked well for this. Maybe in a couple years and once cabal-install is reasonably stable, some unconventional distro like GoboLinux or NixOS might meet my standards :-) ~Isaac ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Data constructors versus types
[EMAIL PROTECTED] wrote: [McCarthy's] aim was to use the mathematical formalismus as languages and not as calculi. This is the root of the historical fact that he never took the Lambda-Calculus conversion rules as a sound basis for LISP implementation. So, I believe it is not so briliant an idea to confound the Church calculus with Lisp! It's difficult to extricate the two, as Lisp McCarthy's experience shows. The decision to use lambda notation without the accompanying semantics would have been fine if Lisp had not also had first-class functions. But with first-class functions, and without lexical scoping semantics, Lisp suffered from scoping bugs which were only resolved once Lisp's 'lambda' was changed to follow Church's semantics, as Sussman and Steele originally did for Scheme. When CL adopted lexical scoping, it was seen as a choice, but it wasn't really much of a choice. The choice was between continuing with a fundamentally buggy language and working around those bugs somehow, or fixing it by adopting Church's lexical scoping rules. Wherever you look, you find plenty of occasions to err, it suffices to put yourself in a mode of a dead person from the movie The sixth sense of M. Night Shyamalan, with Bruce Willis, and Haley Joel Osment. I see dead languages... Anton ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Reflection.Emit in Haskell
As a .NET (C#/F#) programmer learning Haskell, I would love to know the best online sources about run-time compilation etc. like Reflection.Emit in .NET. I am making heavy use of this .NET API to compile customized (regular-expressions-) FSAs at run-time and want to learn how I might achieve the same in Haskell. Book or online article references specific to this issue will be highly appreciated ^_^ Best Regards, Cetin Sert INF 521, 4-6-2 69120 Heidelberg Germany http://www.corsis.de ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Data constructors versus types
[EMAIL PROTECTED] wrote: [...] I heard it somewhere trustworthy. Instinctively, I would guess somewhere into the direction of Graham, but I'm not sure at all. On the other hand, you can be absolutely sure that I didn't get it off the next warez-board nor from Bill Gates. The Story, afaicr, went along the lines of Professor writes something for a cool paper about some calculus, student gets hold of it, implements it and completely baffles the professor, he didn't ever dare to think about letting that one run on a computer. It might be one of those apples that didn't fall off trees while Newton had his idea about gravity, but then it's a complete, nice story with a nice morale on its own. After all, lisp's history isn't as important for me than its semantics, and everything I read about it was kind of accidental, it just wasn't uninteresting enough to skip. -- (c) this sig last receiving data processing entity. Inspect headers for past copyright information. All rights reserved. Unauthorised copying, hiring, renting, public performance and/or broadcasting of this signature prohibited. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] shootout using 6.6?
http://shootout.alioth.debian.org/gp4/haskell.php Anyone know if the Language Shootout is actually using GHC 6.6 or is that a typo? Thanks, Greg ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] shootout using 6.6?
garious: [1]http://shootout.alioth.debian.org/gp4/haskell.php Anyone know if the Language Shootout is actually using GHC 6.6 or is that a typo? It's using 6.6 till the gentoo 6.8 package is more widely distributed. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] STM in F#
http://cs.hubfs.net/blogs/hell_is_other_languages/archive/2008/01/16/4565.aspx I imagine this can only ease the process of learning Haskell, and broaden the base of possible Haskellers, as more people on using .NET stuff become familiar with modern typed FP. -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] STM in F#
On 17 Jan 2008, at 7:02 PM, Don Stewart wrote: http://cs.hubfs.net/blogs/hell_is_other_languages/archive/ 2008/01/16/4565.aspx I imagine this can only ease the process of learning Haskell, and broaden the base of possible Haskellers, as more people on using .NET stuff become familiar with modern typed FP. Indeed, these days I think the main advantage of Haskell is not the feature set (the same features can be used nicely in Perl (well, nicely for Perl), or not-so-nicely in Python), but rather, the fact that Haskell is *designed* for such things, so it's syntax makes things that are verbose in Perl or Python natural. jcc ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Reflection.Emit in Haskell
Cetin Sert schrieb: As a .NET (C#/F#) programmer learning Haskell, I would love to know the best online sources about run-time compilation etc. like Reflection.Emit in .NET. I am making heavy use of this .NET API to compile customized (regular-expressions-) FSAs at run-time and want to learn how I might achieve the same in Haskell. Book or online article references specific to this issue will be highly appreciated ^_^ I am not familiar with C# but I think what you looking for is the GHC api which allows you to compile haskell expressions at runtime. Look for metaplug on hackage (http://hackage.haskell.org/cgi-bin/hackage-scripts/package/metaplug-0.1.1). In its source you ll find an example on how to use the api. You may of course use metaplug itself. I must warn you though that the GHC api is not the best documented and maintained. Currently (ghc 6.8.1) f.i. it seems that reloading modules is broken. The most official docu is here: http://www.haskell.org/haskellwiki/GHC/As_a_library. regards, Martin ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANNOUNCE: HStringTemplate -- An Elegant, Functional, Nifty Templating Engine for Haskell
Graham, I'm sort of playing fast and loose with referential transparency here, as I actually am with stringTemplateFileGroup as well. They both use unsafeIO to do what they want, and in corner cases could give silly, though not dangerous results (i.e., in the sense of being hazardous to your program, these calls are substantially less worrisome than head). stringTemplateFileGroup could conceivably be in IO, if it was strict in reading all the files in the directory it was passed, but cacheSTGroup would force every access to a group to take place in IO, which would make the library somewhat of a pain to work with. My semi-justification for this is that its referentially- transparent-enough for most use cases, in that just about the only thing one would be doing with a StringTemplate result would be outputting it again in some form anyway. In my experience, being able to hot-edit templates for a live app is a key benefit of a templating system, and forcing everything into IO to get that seems like an undue burden on end-users. On the other hand, I'm also open to implementing an IO API that's safe and renaming the current functions to something somewhat scarier, or moving both them and their IO equivs to distinct modules so that end users could choose which to import. A number of options seem reasonable here. --Sterl. (btw, I fixed the typo you emailed me about in the repo, and also made a few other changes I documented at http:// fmapfixreturn.wordpress.com/) On Jan 16, 2008, at 8:19 PM, Graham Fawcett wrote: On Jan 14, 2008 2:47 AM, Sterling Clover [EMAIL PROTECTED] wrote: HStringTemplate is a port of Terrence Parr's lovely StringTemplate (http://www.stringtemplate.org) engine to Haskell. This is very cool. Your docs describe a function, cacheSTGroup: cacheSTGroup :: Int - STGen a - STGen a Given an integral amount of seconds and a group, returns a group cached for that span of time. Does not cache misses. How does this work without breaking referential transparency? Shouldn't it be in the IO monad if it is time-dependent? Graham ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Reflection.Emit in Haskell
That would be possible, but wouldn't Template Haskell also be an option? Peter Martin Lütke wrote: Cetin Sert schrieb: As a .NET (C#/F#) programmer learning Haskell, I would love to know the best online sources about run-time compilation etc. like Reflection.Emit in .NET. I am making heavy use of this .NET API to compile customized (regular-expressions-) FSAs at run-time and want to learn how I might achieve the same in Haskell. Book or online article references specific to this issue will be highly appreciated ^_^ I am not familiar with C# but I think what you looking for is the GHC api which allows you to compile haskell expressions at runtime. Look for metaplug on hackage (http://hackage.haskell.org/cgi-bin/hackage-scripts/package/metaplug-0.1.1). In its source you ll find an example on how to use the api. You may of course use metaplug itself. I must warn you though that the GHC api is not the best documented and maintained. Currently (ghc 6.8.1) f.i. it seems that reloading modules is broken. The most official docu is here: http://www.haskell.org/haskellwiki/GHC/As_a_library. regards, Martin ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] STM in F#
Reminds me of a song, I'm dreaming of a ... dotnet Haskell... I find it such a petty no real work seems to be done on that. Okay, the performance might not be optimal. Okay, you might have two huge frameworks that overlap. Okay, using the .NET stuff would mean some kind of automatic IO monadic wrapper generator, but surely with the .NET reflection support, this would be possible. But look at the advantages... Of course Haskell is a research language, and avoid success at all cost is the goal. But unfortunately, IMHO Haskell does make a lot of sense, so... Ah well, I should stop nagging about this :-) Jonathan Cast wrote: On 17 Jan 2008, at 7:02 PM, Don Stewart wrote: http://cs.hubfs.net/blogs/hell_is_other_languages/archive/2008/01/16/4565.aspx I imagine this can only ease the process of learning Haskell, and broaden the base of possible Haskellers, as more people on using .NET stuff become familiar with modern typed FP. Indeed, these days I think the main advantage of Haskell is not the feature set (the same features can be used nicely in Perl (well, nicely for Perl), or not-so-nicely in Python), but rather, the fact that Haskell is *designed* for such things, so it's syntax makes things that are verbose in Perl or Python natural. jcc ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] STM in F#
On Fri, 2008-01-18 at 07:32 +0100, Peter Verswyvelen wrote: Reminds me of a song, I'm dreaming of a ... dotnet Haskell... I find it such a petty no real work seems to be done on that. No one is stopping you. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Reflection.Emit in Haskell
Hello Cetin,
Friday, January 18, 2008, 12:52:27 AM, you wrote:
As a .NET (C#/F#) programmer learning Haskell, I would love to know
the best online sources about run-time compilation etc. like
hs-plugins (unix-only afair), and GHC-as-a-library
Reflection.Emit in .NET. I am making heavy use of this .NET API to
compile customized (regular-expressions-) FSAs at run-time and want
to learn how I might achieve the same in Haskell. Book or online
article references specific to this issue will be highly appreciated ^_^
it was Runtime_Compilation page on old Haskell wiki, written by Andrew
Bromage and me. in short, some form of run-time compilation works
without actual compiling code. in particular, RegEx package compiles
regexps on the fly. my own program includes very simple variant of
run-time compiled regexps:
-- Compiled regexpExample
data RegExpr = RE_End --
| RE_Anything-- *
| RE_AnyStr RegExpr -- '*':bc*
| RE_FromEnd RegExpr -- '*':bc
| RE_AnyChar RegExpr -- '?':bc
| RE_CharChar RegExpr-- 'a':bc
-- |Compile string representation of regexpr into RegExpr
compile_RE s = case s of
- RE_End
*- RE_Anything
'*':cs | cs `contains` '*' - RE_AnyStr (compile_RE cs)
| otherwise - RE_FromEnd (compile_RE$ reverse s)
'?':cs - RE_AnyChar (compile_RE cs)
c :cs - RE_Char c (compile_RE cs)
-- |Check match of string s with regexpr re
match_RE re s = case re of
RE_End- null s
RE_Anything - True
RE_AnyStr r - any (match_RE r) (tails s)
RE_FromEnd r - match_RE r (reverse s)
RE_AnyChar r - case s of
- False
_:xs - match_RE r xs
RE_Char c r - case s of
- False
x:xs - x==c match_RE r xs
-- |Check match of string s with regexpr re, represented as string
match re {-s-} = match_RE (compile_RE re) {-s-}
actually, you will not find anything unusual here. the code for
matching with RegExpr is just constructed at runtime (as tree of
closures) which makes matching quite efficient
--
Best regards,
Bulatmailto:[EMAIL PROTECTED]
___
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe
