Re: [Haskell-cafe] Why is Haskell flagging this?
Huh, that's weird, I just copy and pasted this into a new file and it worked for me. I did prepend the line module RandTest where -- ryan On Tue, Dec 21, 2010 at 6:43 PM, michael rice nowg...@yahoo.com wrote: I changed your die function to rollDie in function roll2Dice (I assume that's what you meant) but get the errors listed below. Michael import Control.Monad.State import Control.Monad import System.Random type GeneratorState = State StdGen genRandom :: Random a = GeneratorState a genRandom = State random -- similar genRandomR :: Random a = (a,a) - GeneratorState a genRandomR = State . randomR rollDie :: GeneratorState Int rollDie = genRandomR (1,6) roll2Dice :: GeneratorState Int roll2Dice = liftM2 (+) rollDie rollDie === Prelude :l craps7 [1 of 1] Compiling Main ( craps7.hs, interpreted ) craps7.hs:7:12: Not in scope: data constructor `State' craps7.hs:11:13: Not in scope: data constructor `State' Failed, modules loaded: none. Prelude --- On *Tue, 12/21/10, Ryan Ingram ryani.s...@gmail.com* wrote: From: Ryan Ingram ryani.s...@gmail.com Subject: Re: [Haskell-cafe] Why is Haskell flagging this? To: michael rice nowg...@yahoo.com Cc: David Leimbach leim...@gmail.com, Daniel Fischer daniel.is.fisc...@googlemail.com, haskell-cafe@haskell.org Date: Tuesday, December 21, 2010, 7:00 PM First, let's make some useful operations in your GeneratorState monad: -- State :: (s - (a,s)) - State s a -- random :: Random a = StdGen - (a, StdGen) genRandom :: Random a = GeneratorState a genRandom = State random -- similar genRandomR :: Random a = (a,a) - GeneratorState a genRandomR = State . randomR rollDie :: GeneratorState Int rollDie = genRandomR (1,6) roll2Dice :: GeneratorState Int roll2Dice = liftM2 (+) die die These can be used to simplify a lot of the code here. -- ryan On Fri, Dec 17, 2010 at 5:55 PM, michael rice nowg...@yahoo.comhttp://mc/compose?to=nowg...@yahoo.com wrote: Paul Graham refers to all those features as orthogonality (On Lisp, pg. 63) and you're right, Haskell has it in spades, but it takes time to understand all of it and even more time to use it effectively. One almost needs a checklist. But I think I'm catching on. I programmed this craps simulation last week. It's a problem from Problems For Computer Solution, Gruenberger Jaffray, 1965, The RAND Corp. import Control.Monad.State import System.Random type GeneratorState = State StdGen data Craps a = Roll a | Win a | Lose a deriving (Show) f :: Craps [Int] - GeneratorState (Craps [Int]) f (Roll []) = do g0 - get let (d1,g1) = randomR (1,6) g0 (d2,g2) = randomR (1,6) g1 t1 = d1+d2 put g2 case t1 of 2 - return (Lose [t1]) 3 - return (Lose [t1]) 7 - return (Win [t1]) 11 - return (Win [t1]) _ - do g2 - get let (d3,g3) = randomR (1,6) g2 (d4,g4) = randomR (1,6) g3 t2 = d3+d4 put g4 if t2 == t1 then do return (Win [t1,t2]) else if t2 == 7 then do return (Lose [t1,t2]) else f (Roll [t2,t1]) f (Roll l) = do g0 - get let (d1,g1) = randomR (1,6) g0 (d2,g2) = randomR (1,6) g1 t = d1+d2 if t == (last l) then do put g2 return (Win (reverse (t:l))) else if t == 7 then do put g2 return (Lose (reverse (t:l))) else do put g2 f (Roll (t:l)) progressive (z@(x:xs),n) (Win _) = let b = x + (last xs) in (init xs,n+b) progressive (z@(x:xs),n) (Lose _) = let b = x + (last xs) in (z ++ [b],n-b) *Main let r = evalState (sequence $ replicate 6 (f (Roll []))) (mkStdGen 987) *Main r [Win [8,12,10,3,8],Win [5,9,10,11,12,11,8,9,5],Win [7],Lose [9,7],Win [5,5],Win [5,2,6,4,6,8,5]] *Main foldl progressive ([1..10],0) r ([6],49) Function f generates the roll cycle outcomes which are then folded with the progressive betting system. In the final answer, the [6] is what's left of the original betting list [1..10]. The betting list is used to determine the bet: always bet the (first + last) of
Re: [Haskell-cafe] [darcs-users] Darcs failure
Andrew, Thanks for your report. Indeed, please direct future reports to darcs-users or b...@darcs.net darcs: bug at src/URL.hs:246 compiled Sep 12 2010 20:24:56 Another possible bug in URL.waitNextUrl: curl_multi_perform() - no running handles See http://wiki.darcs.net/BugTracker/Reporting for help on bug reporting. I think this was resolved in darcs-2.5 [1]. If not, it's at least resolved in what will become Darcs 2.8. Unfortunately, our release notes don't mention it [2], so I'm not 100% sure Cheers, Eric [1] http://bugs.darcs.net/issue1770 [2] http://wiki.darcs.net/Releases/2.5 -- Eric Kow http://www.nltg.brighton.ac.uk/home/Eric.Kow For a faster response, try +44 (0)1273 64 2905 or xmpp:ko...@jabber.fr (Jabber or Google Talk only) signature.asc Description: Digital signature ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Rendering of hask in new wiki (MSIE6)
Statistics from A tour of the Haskell Monad functions (on my site), after 15.351 pageviews: I find it surprising that nobody using google chrome ever browsed your site. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Why is Haskell flagging this?
On Wednesday 22 December 2010 12:03:01, Ryan Ingram wrote: Huh, that's weird, I just copy and pasted this into a new file and it worked for me. As a guess, you have mtl-1.*? In mtl-2.*, State s is made a type synonym for StateT s Identity, so there's no longer a data constructor State. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] [darcs-users] Darcs failure
On 22/12/2010 11:08 AM, Eric Kow wrote: Andrew, Thanks for your report. Indeed, please direct future reports to darcs-users or b...@darcs.net That would require me to sign up to yet another mailing list just to report one bug. And given that we're talking about a prebuilt binary being trivially broken out-of-the-box, presumably it's already a widely known bug. I think this was resolved in darcs-2.5 [1]. If not, it's at least resolved in what will become Darcs 2.8. Unfortunately, our release notes don't mention it [2], so I'm not 100% sure Right. So 2.4.4 is broken, and I just need a newer version? Presumably the only way to do that would be to build one. (?) As I understand it, apt-get and similar tools are designed to 100% prevent you having any choice whatsoever over the version numbers of stuff that gets installed. On the other hand, presumably cabal-install will happily build anything I ask it to... ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] implementing RealFloat decodeFloat
Hi everyone, I've been working on [0] Haskell bindings for [1] libqd for [2] double-double and quad-double arithmetic, and have been struggling to implement [3] RealFloat, in particular [4] decodeFloat, mostly because of its postcondition but also some issues relating to variable precision: ---8--- If decodeFloat x yields (m,n), then x is equal in value to m*b^^n, where b is the floating-point radix, and furthermore, either m and n are both zero or else b^(d-1) = m b^d, where d is the value of floatDigits x. In particular, decodeFloat 0 = (0,0). ---8--- (BTW: that should probably really be ... = abs m ...; perhaps this code could be added to the report and/or documentation, if it is correct: validDecode :: RealFloat f = f - Bool validDecode f = case decodeFloat f of (0,0) - True (m, e) - b^(d-1) = abs m abs m b^d where b = floatRadix f d = floatDigits f ) The double-double and quad-double types do not have a fixed precision, though they do have a fixed minimum precision: this means that decodeFloat will (in general) lose some precision. This is because for example in: data DoubleDouble = DoubleDouble !CDouble !CDouble dd = DoubleDouble a b the semantics are that dd = a + b, with |a||b|; coupled with the IEEE implicit leading 1 bit, this means that there may be large gaps between exponents: for example: 1 + 0.5**100 :: DoubleDouble. So far I've got a mostly working implementation thus: decodeFloat !(DoubleDouble a b) = case (decodeFloat a, decodeFloat b) of ((0, 0), (0, 0)) - (0, 0) ((0, 0), (m, e)) - (m `shiftL` f, e - f) ((m, e), (0, 0)) - (m `shiftL` f, e - f) ((m1, e1), (m2, e2)) - let fixup m e = if m mMin then fixup (m `shiftL` 1) (e - 1) else if m = mMax then fixup (m `shiftR` 1) (e + 1) else (m, e) mMin = 1 `shiftL` (ff - 1) mMax = 1 `shiftL` ff ff = floatDigits (0 :: DoubleDouble) g = e1 - e2 - f in fixup ((m1 `shiftL` f) + (m2 `shiftR` g)) (e1 - f) where f = floatDigits (0 :: CDouble) This does meet the postcondition as specified (which leads to breakage in other RealFloat methods), but has a recursion with no termination proof (so far), and is lossy in general: let check f = uncurry encodeFloat (decodeFloat f) == f check (1 + 0.5 ** 120 :: DoubleDouble) False It does however seem to meet a weaker condition: let check2 f = (decodeFloat . (`asTypeOf` f) . uncurry encodeFloat . decodeFloat $ f) == decodeFloat f check2 (1 + 0.5 ** 120 :: DoubleDouble) True Questions: 1. Is this weaker condition likely to be good enough in practice? 2. Can my implementation of decodeFloat be simplified? Thanks for any insights, Claude [0] http://hackage.haskell.org/package/qd [1] http://crd.lbl.gov/~dhbailey/mpdist/ [2] http://crd.lbl.gov/~dhbailey/dhbpapers/arith15.pdf [3] http://hackage.haskell.org/packages/archive/base/latest/doc/html/Prelude.html#t:RealFloat [4] http://hackage.haskell.org/packages/archive/base/latest/doc/html/Prelude.html#v:decodeFloat -- http://claudiusmaximus.goto10.org ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] ANNOUNCE: storable-endian
Hi cafe,
I've released storable-endian
http://hackage.haskell.org/package/storable-endian
It defines types like {{Int,Word}{16,32,64},Double,Float}{LE,BE} (for
example Int32BE) etc. with a corresponding Storable instance.
It is needed for binary interoperability with libraries or network
protocols with fixed endianness. Hope you find it useful.
--
Eugene Kirpichov
Senior Software Engineer,
Grid Dynamics http://www.griddynamics.com/
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[Haskell-cafe] Windows Haskell Platform download link is broken
Windows Haskell Platform download link goes nowhere :- http://hackage.haskell.org/platform/windows.html The Download Haskell for Windows is broken :- http://lambda.galois.com/hp-tmp/2010.2.0.0/HaskellPlatform-2010.2.0.0-setup.exe Aaron ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Missing Parsec library in latest stable GHC
Missing Parsec library :- scheme.o(.text+0x4fa):fake: undefined reference to `parseczm2zi1zi0zi0_TextziParserCombinatorsziParsecziCombinator_skipMany1_closure' scheme.o(.text+0x501):fake: undefined reference to `parseczm2zi1zi0zi0_TextziPaserCombinatorsziParsecziChar_space_closure' scheme.o(.text+0x5c2):fake: undefined reference to `parseczm2zi1zi0zi0_TextziParserCombinatorsziParsecziChar_oneOf_closure' scheme.o(.text+0x63a):fake: undefined reference to `mtlzm1zi1zi0zi0_ControlziMonadziTrans_zdf1_closure' GHC from :- http://www.haskell.org/ghc/dist/stable/dist/ ghc-7.0.1.20101221-i386-windows.exehttp://www.haskell.org/ghc/dist/stable/dist/ghc-7.0.1.20101221-i386-windows.exe and earlier. Aaron ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Latest Haskell Platform for Windows
Could someone please point me at a copy of the latest Haskell platform or a working GHC please. Many thanks in advance, Aaron ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Latest Haskell Platform for Windows
Maybe this one: http://hackage.haskell.org/platform/2010.2.0.0/HaskellPlatform-2010.2.0.0-setup.exe /J On 22 December 2010 17:15, Aaron Gray aaronngray.li...@gmail.com wrote: Could someone please point me at a copy of the latest Haskell platform or a working GHC please. Many thanks in advance, Aaron ___ 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] Missing Parsec library in latest stable GHC
What commands did you enter to produce this error? Ahanks, Antoine On Wed, Dec 22, 2010 at 9:54 AM, Aaron Gray aaronngray.li...@gmail.com wrote: Missing Parsec library :- scheme.o(.text+0x4fa):fake: undefined reference to `parseczm2zi1zi0zi0_TextziParserCombinatorsziParsecziCombinator_skipMany1_closure' scheme.o(.text+0x501):fake: undefined reference to `parseczm2zi1zi0zi0_TextziPaserCombinatorsziParsecziChar_space_closure' scheme.o(.text+0x5c2):fake: undefined reference to `parseczm2zi1zi0zi0_TextziParserCombinatorsziParsecziChar_oneOf_closure' scheme.o(.text+0x63a):fake: undefined reference to `mtlzm1zi1zi0zi0_ControlziMonadziTrans_zdf1_closure' GHC from :- http://www.haskell.org/ghc/dist/stable/dist/ ghc-7.0.1.20101221-i386-windows.exe and earlier. Aaron ___ 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] Latest Haskell Platform for Windows
aaronngray.lists: Could someone please point me at a copy of the latest Haskell platform or a working GHC please. Many thanks in advance, The links on haskell.org/platform should work (there was a domain change, so you'll no longer see lambda.galois.com links). -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Latest Haskell Platform for Windows
On 22 December 2010 16:41, Don Stewart d...@galois.com wrote: aaronngray.lists: Could someone please point me at a copy of the latest Haskell platform or a working GHC please. Many thanks in advance, The links on haskell.org/platform should work (there was a domain change, so you'll no longer see lambda.galois.com links). Okay, thanks. I obviously came along at the wrong time :) Aaron ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Missing Parsec library in latest stable GHC
On 22 December 2010 16:27, Antoine Latter aslat...@gmail.com wrote: What commands did you enter to produce this error? ghc scheme.hs I am still getting this on the 2010 2.0.0 release. Aaron Ahanks, Antoine On Wed, Dec 22, 2010 at 9:54 AM, Aaron Gray aaronngray.li...@gmail.com wrote: Missing Parsec library :- scheme.o(.text+0x4fa):fake: undefined reference to `parseczm2zi1zi0zi0_TextziParserCombinatorsziParsecziCombinator_skipMany1_closure' scheme.o(.text+0x501):fake: undefined reference to `parseczm2zi1zi0zi0_TextziPaserCombinatorsziParsecziChar_space_closure' scheme.o(.text+0x5c2):fake: undefined reference to `parseczm2zi1zi0zi0_TextziParserCombinatorsziParsecziChar_oneOf_closure' scheme.o(.text+0x63a):fake: undefined reference to `mtlzm1zi1zi0zi0_ControlziMonadziTrans_zdf1_closure' GHC from :- http://www.haskell.org/ghc/dist/stable/dist/ ghc-7.0.1.20101221-i386-windows.exe and earlier. Aaron ___ 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] Missing Parsec library in latest stable GHC
ghc doesn't, by default, go searching for packages to link in to the resulatant executable.. If you try 'ghc --make scheme.hs' your example will work better. You can also specify what to link manually, but --make works pretty well most of the time. In ghc version 7 '--make' is the default, but until that's more widely distributed you'll want to get used to using the switch. Take care, Antoine On Wed, Dec 22, 2010 at 10:36 AM, Aaron Gray aaronngray.li...@gmail.com wrote: On 22 December 2010 16:27, Antoine Latter aslat...@gmail.com wrote: What commands did you enter to produce this error? ghc scheme.hs Aaron Ahanks, Antoine On Wed, Dec 22, 2010 at 9:54 AM, Aaron Gray aaronngray.li...@gmail.com wrote: Missing Parsec library :- scheme.o(.text+0x4fa):fake: undefined reference to `parseczm2zi1zi0zi0_TextziParserCombinatorsziParsecziCombinator_skipMany1_closure' scheme.o(.text+0x501):fake: undefined reference to `parseczm2zi1zi0zi0_TextziPaserCombinatorsziParsecziChar_space_closure' scheme.o(.text+0x5c2):fake: undefined reference to `parseczm2zi1zi0zi0_TextziParserCombinatorsziParsecziChar_oneOf_closure' scheme.o(.text+0x63a):fake: undefined reference to `mtlzm1zi1zi0zi0_ControlziMonadziTrans_zdf1_closure' GHC from :- http://www.haskell.org/ghc/dist/stable/dist/ ghc-7.0.1.20101221-i386-windows.exe and earlier. Aaron ___ 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] Rendering of hask in new wiki (MSIE6)
On Wed, 22 Dec 2010 13:22:07 +0100, David Virebayre dav.vire+hask...@gmail.com wrote: Statistics from A tour of the Haskell Monad functions (on my site), after 15.351 pageviews: I find it surprising that nobody using google chrome ever browsed your site. That is indeed strange; below statistics for the same page from a different statistics provider: Period: 2009-07-08 .. 2010-12-22 (the total period that this counter is active) Page views: 11.164 Unique page views: 10.380 Number of new visitors: 6.358 Browsers (18 browsers were used): Page Unique page viewsviews 1. Firefox 5.4175.015 2. Chrome2.2192.052 3. Opera 1.2291.188 4. Safari 811 747 5. Mozilla 689 646 6. Internet Explorer 665 608 7. Konqueror64 58 8. Camino 39 39 9. Uzbl 75 10. Midori54 Operating Systems (15 operating systems were used): 1. Windows4.7764.443 2. Linux 4.7014.378 3. Macintosh 1.5171.410 4. FreeBSD 58 49 5. iPhone23 20 6. Android 16 13 7. SunOS 15 12 8. (not set) 12 11 9. NetBSD 86 10. iPad 77 Regards, Henk-Jan van Tuyl -- http://Van.Tuyl.eu/ http://members.chello.nl/hjgtuyl/tourdemonad.html -- ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Missing Parsec library in latest stable GHC
On Wednesday 22 December 2010 16:54:04, Aaron Gray wrote: Missing Parsec library :- scheme.o(.text+0x4fa):fake: undefined reference to `parseczm2zi1zi0zi0_TextziParserCombinatorsziParsecziCombinator_skipMany 1_closure' scheme.o(.text+0x501):fake: undefined reference to `parseczm2zi1zi0zi0_TextziPaserCombinatorsziParsecziChar_space_closure' scheme.o(.text+0x5c2):fake: undefined reference to `parseczm2zi1zi0zi0_TextziParserCombinatorsziParsecziChar_oneOf_closure' scheme.o(.text+0x63a):fake: undefined reference to `mtlzm1zi1zi0zi0_ControlziMonadziTrans_zdf1_closure' GHC from :- http://www.haskell.org/ghc/dist/stable/dist/ ghc-7.0.1.20101221-i386-windows.exehttp://www.haskell.org/ghc/dist/stab le/dist/ghc-7.0.1.20101221-i386-windows.exe and earlier. Aaron Since 6.8 iirc, GHC no longer comes with parsec, you have to install the package yourself if you want to use it, cabal install parsec also mtl is no longer one of the libraries that come with GHC, cabal install mtl HTH, Daniel ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Functor = Applicative = Monad
On 14/12/2010 08:35, Isaac Dupree wrote: On 12/14/10 03:13, John Smith wrote: I would like to formally propose that Monad become a subclass of Applicative, with a call for consensus by 1 February. The change is described on the wiki at http://haskell.org/haskellwiki/Functor-Applicative-Monad_Proposal, That page isn't written as a proposal yet, it's written as a bunch of ideas. I would be happy to see something along the lines of Bas van Dijk's work http://permalink.gmane.org/gmane.comp.lang.haskell.libraries/14740 . This is a proposal with far-reaching consequences, and with several alternative designs. I'm not sure I understand all the tradeoffs. Some parts of the proposal are orthogonal to the rest (e.g. changing fmap to map), and should probably be considered separately. Could someone please write a detailed proposal, enumerating all the pros and cons, and the rationale for this design compared to other designs? Cheers, Simon ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Missing Parsec library in latest stable GHC
On 22 December 2010 16:47, Antoine Latter aslat...@gmail.com wrote: ghc doesn't, by default, go searching for packages to link in to the resulatant executable.. If you try 'ghc --make scheme.hs' your example will work better. Are great, thanks a lot. You can also specify what to link manually, but --make works pretty well most of the time. In ghc version 7 '--make' is the default, but until that's more widely distributed you'll want to get used to using the switch. Yes it was linking before I upgraded GHC, hence my confusion :) Many thanks Antoine, Aaron Take care, Antoine On Wed, Dec 22, 2010 at 10:36 AM, Aaron Gray aaronngray.li...@gmail.com wrote: On 22 December 2010 16:27, Antoine Latter aslat...@gmail.com wrote: What commands did you enter to produce this error? ghc scheme.hs Aaron Ahanks, Antoine On Wed, Dec 22, 2010 at 9:54 AM, Aaron Gray aaronngray.li...@gmail.com wrote: Missing Parsec library :- scheme.o(.text+0x4fa):fake: undefined reference to `parseczm2zi1zi0zi0_TextziParserCombinatorsziParsecziCombinator_skipMany1_closure' scheme.o(.text+0x501):fake: undefined reference to `parseczm2zi1zi0zi0_TextziPaserCombinatorsziParsecziChar_space_closure' scheme.o(.text+0x5c2):fake: undefined reference to `parseczm2zi1zi0zi0_TextziParserCombinatorsziParsecziChar_oneOf_closure' scheme.o(.text+0x63a):fake: undefined reference to `mtlzm1zi1zi0zi0_ControlziMonadziTrans_zdf1_closure' GHC from :- http://www.haskell.org/ghc/dist/stable/dist/ ghc-7.0.1.20101221-i386-windows.exe and earlier. Aaron ___ 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] [darcs-users] Darcs failure
On Wed, Dec 22, 2010 at 5:09 AM, Andrew Coppin andrewcop...@btinternet.comwrote: On 22/12/2010 11:08 AM, Eric Kow wrote: Andrew, Thanks for your report. Indeed, please direct future reports to darcs-users or b...@darcs.net That would require me to sign up to yet another mailing list just to report one bug. Just so you know, that's not true in this case. Anyone can send to b...@darcs and darcs-users was still using human moderators last I checked. Jason ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Missing Parsec library in latest stable GHC
On 22 December 2010 16:51, Daniel Fischer daniel.is.fisc...@googlemail.comwrote: On Wednesday 22 December 2010 16:54:04, Aaron Gray wrote: Missing Parsec library :- scheme.o(.text+0x4fa):fake: undefined reference to `parseczm2zi1zi0zi0_TextziParserCombinatorsziParsecziCombinator_skipMany 1_closure' scheme.o(.text+0x501):fake: undefined reference to `parseczm2zi1zi0zi0_TextziPaserCombinatorsziParsecziChar_space_closure' scheme.o(.text+0x5c2):fake: undefined reference to `parseczm2zi1zi0zi0_TextziParserCombinatorsziParsecziChar_oneOf_closure' scheme.o(.text+0x63a):fake: undefined reference to `mtlzm1zi1zi0zi0_ControlziMonadziTrans_zdf1_closure' GHC from :- http://www.haskell.org/ghc/dist/stable/dist/ ghc-7.0.1.20101221-i386-windows.exehttp://www.haskell.org/ghc/dist/stab le/dist/ghc-7.0.1.20101221-i386-windows.exe and earlier. Aaron Since 6.8 iirc, GHC no longer comes with parsec, you have to install the package yourself if you want to use it, cabal install parsec This does not seem to be needed. import Text.ParserCombinators.Parsec seems fine. also mtl is no longer one of the libraries that come with GHC, cabal install mtl What is mtl ? Thanks, Aaron HTH, Daniel ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Why is Haskell flagging this?
Interesting. In that case, state f = StateT $ \s - Identity (f s) allows state to replace State in that code. On Wed, Dec 22, 2010 at 4:56 AM, Daniel Fischer daniel.is.fisc...@googlemail.com wrote: On Wednesday 22 December 2010 12:03:01, Ryan Ingram wrote: Huh, that's weird, I just copy and pasted this into a new file and it worked for me. As a guess, you have mtl-1.*? In mtl-2.*, State s is made a type synonym for StateT s Identity, so there's no longer a data constructor State. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Infinite lists in real world programs
Patai, I read your paper on Elerea. It wasn't easy :), but I think I got the picture. So I would have 2 questions : I made a simple function which turns an infinite list into a signal : fromList :: [a] - SignalGen (Signal a) fromList xs = stateful xs tail = memo . fmap head 1) It does what I want, but is it the good way to do it? 2) Since the returned signal may be used in several places and since I obtain it through the generic fmap (and not through an Elerea primitive), I guessed I had to memo it instead of simply using return. Did I guess right? 3) Concerning the functionnality added by the Param implementation, I have the impression that the same can be achieved through the use of an external signal in Simple (*). Am I right? If so, why did you make the Param alternative? (*) (ext, sink) - external 'a' driver - start $ someSigGen ext sink 'b' driver sink 'c' driver sink 'd' driver etc... 2010/12/16 Patai Gergely patai_gerg...@fastmail.fm So in the result of (a = f), the first element is taken from the first element of applying f to the first element of a; the second element is the second element in the result of applying f to the second element of a; and so on. Off the top of my head I am not sure what this corresponds to in terms of agents or where it would be useful, but I'm sure it must correspond to something interesting. In short, join corresponds to continuously sampling a stream of streams. In other words, it turns a higher-order stream into a dynamic data-flow network. That's exactly what the Elerea library [1] is good for: it allows you to do this in constant time instead of the quadratic cost of the pure implementation, but it forces you to traverse streams sequentially -- fortunately, that's exactly what you want to do most of the time. There is also a paper behind the library, which might help a bit in getting a clearer picture [2] (the paper also has an updated version in the process of being published). Gergely [1] http://hackage.haskell.org/package/elerea [2] http://sgate.emt.bme.hu/documents/patai/publications/PataiWFLP2010.pdf -- http://www.fastmail.fm - One of many happy users: http://www.fastmail.fm/docs/quotes.html ___ 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] Matlab Style Logic Operations ala V1.*(V20) on Vectors and Matrices with HMatrix ??
Hi Henning, You definitly caught me on that little Germanism :-) About Your comments - a lot to learn and take in, but it really helps. - Thanks a lot. I just manged to get the Matrix masking running code looks like (code A see below). Two quick questions: question 1. u see the two commented lines I tried to get ur original line running, but didn't know how to specify f ## Code import Numeric.LinearAlgebra import Graphics.Plot matrix1 = fromLists [[0 .. 5],[30 .. 35],[50 .. 55]] matrix2 = fromLists [[-1,2],[-3,4],[5,-6]] -- matrix1 = buildMatrix 3 4 ( (r,c) - fromIntegral r * fromIntegral c) (34) -- posPart v = mapVector (\a - if a=0 then a else 0) v -- function2map a1 a2 = (\a1 a2 - if a1=0 then a2/a1 else a1/a2) matrixfunction x y = liftMatrix2 (zipVectorWith(\a1 a2 - if a2=0 then a1 else 0)) x y matrix3 = matrixfunction matrix1 matrix2 disp = putStr . disps 2 main = do disp matrix1 disp matrix2 -- disp matrix3 mesh matrix1 # question 2: - the compiler comes up with some weired data type problem -- ghci has no problem this line : matrixTest_Fail.hs:5:10: Ambiguous type variable `t' in the constraints: `Element t' arising from a use of `fromLists' at matrixTest_Fail.hs:5:10-38 `Num t' arising from the literal `1' at matrixTest_Fail.hs:5:22 Possible cause: the monomorphism restriction applied to the following: matrix2 :: Matrix t (bound at matrixTest_Fail.hs:5:0) Probable fix: give these definition(s) an explicit type signature or use -XNoMonomorphismRestriction ## Code # import Numeric.LinearAlgebra import Graphics.Plot matrix1 = fromLists [[1,2],[3,4],[5,6]] matrix2 = fromLists [[1,2],[3,4],[5,6]] disp = putStr . disps 2 main = do disp matrix1 # -- View this message in context: http://haskell.1045720.n5.nabble.com/Matlab-Style-Logic-Operations-ala-V1-V2-0-on-Vectors-and-Matrices-with-HMatrix-tp3312601p3315761.html Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Identity type
On Tue, Dec 14, 2010 at 10:31 AM, Pierre-Etienne Meunier pierreetienne.meun...@gmail.com wrote: Is there something like an identity type, transparent to the type-checker, in haskell ? For instance, I'm defining an interval arithmetic, with polynomials, matrices, and all that... defined with intervals. The types are : No, such a thing doesn't exist. In fact, it would make the type system undecidable if it did exist. I only know this because a long while ago I really wanted such a thing to exist then tried to work out the consequences and realized it would break the type system. I have found liberal use of 'newtype-deriving' has mitigated my need for it in the specific cases I was interested in. John ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] [darcs-users] Darcs failure
On 23 December 2010 00:09, Andrew Coppin andrewcop...@btinternet.com wrote: Presumably the only way to do that would be to build one. (?) As I understand it, apt-get and similar tools are designed to 100% prevent you having any choice whatsoever over the version numbers of stuff that gets installed. On the other hand, presumably cabal-install will happily build anything I ask it to... Not all Linux package managers provide one version and one version only (though admittedly most do). -- Ivan Lazar Miljenovic ivan.miljeno...@gmail.com IvanMiljenovic.wordpress.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Proof in Haskell
On 22/12/2010 14:48, Artyom Shalkhakov wrote: ..Do you want to prove a property of a function formally, using some kind of formal logic? I am aware that functional languages do not do proofs at term level, but the motivation for my question is to get a precise reason why this is so. The replies from the café have clearly articulated the reasons. Thanks to all, Pat This message has been scanned for content and viruses by the DIT Information Services E-Mail Scanning Service, and is believed to be clean. http://www.dit.ie ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Matlab Style Logic Operations ala V1.*(V20) on Vectors and Matrices with HMatrix ??
On Wed, 22 Dec 2010, gutti wrote: question 1. u see the two commented lines I tried to get ur original line running, but didn't know how to specify f What 'f' ? Do you mean matrixfunction f x y = liftMatrix2 (zipVectorWith f) x y ? ## Code import Numeric.LinearAlgebra import Graphics.Plot matrix1 = fromLists [[0 .. 5],[30 .. 35],[50 .. 55]] matrix2 = fromLists [[-1,2],[-3,4],[5,-6]] -- matrix1 = buildMatrix 3 4 ( (r,c) - fromIntegral r * fromIntegral c) (34) -- posPart v = mapVector (\a - if a=0 then a else 0) v -- function2map a1 a2 = (\a1 a2 - if a1=0 then a2/a1 else a1/a2) matrixfunction x y = liftMatrix2 (zipVectorWith(\a1 a2 - if a2=0 then a1 else 0)) x y matrix3 = matrixfunction matrix1 matrix2 disp = putStr . disps 2 main = do disp matrix1 disp matrix2 -- disp matrix3 mesh matrix1 # question 2: - the compiler comes up with some weired data type problem -- ghci has no problem this line : matrixTest_Fail.hs:5:10: Ambiguous type variable `t' in the constraints: `Element t' arising from a use of `fromLists' at matrixTest_Fail.hs:5:10-38 `Num t' arising from the literal `1' at matrixTest_Fail.hs:5:22 Possible cause: the monomorphism restriction applied to the following: matrix2 :: Matrix t (bound at matrixTest_Fail.hs:5:0) Probable fix: give these definition(s) an explicit type signature or use -XNoMonomorphismRestriction ## Code # import Numeric.LinearAlgebra import Graphics.Plot matrix1 = fromLists [[1,2],[3,4],[5,6]] matrix2 = fromLists [[1,2],[3,4],[5,6]] Before type inference can work, you need to fix the type of at least one number of a set of numbers with known equal type. E.g. matrix1 = fromLists [[1,2],[3,4],[5,6::Double]] or even better, add a type signature: matrix1 :: Matrix Double ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANNOUNCE: storable-endian
On Wed, 22 Dec 2010, Eugene Kirpichov wrote:
Hi cafe,
I've released storable-endian
http://hackage.haskell.org/package/storable-endian
It defines types like {{Int,Word}{16,32,64},Double,Float}{LE,BE} (for
example Int32BE) etc. with a corresponding Storable instance.
It is needed for binary interoperability with libraries or network
protocols with fixed endianness. Hope you find it useful.
How about type constructors LittleEndian and BigEndian?
newtype LittleEndian a = LittleEndian a
Maybe using some type classes you can even get rid of Template Haskell and
get plain Haskell 98?
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Re: [Haskell-cafe] Data.Typeable TypeRep Ord instance.
On Sat, Dec 4, 2010 at 2:08 PM, Serguey Zefirov sergu...@gmail.com wrote: Why TypeRep does have equality and doesn't have ordering? It would be good to have that. Yes, I have wanted that too. It would make maps from types to values possible/efficient. There is a very critical path in jhc that use type-indexed data structures that I have to implement a very hacky workaround for no Ord instance for TypeRep John ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANNOUNCE: storable-endian
On Thu, 23 Dec 2010, Henning Thielemann wrote:
On Wed, 22 Dec 2010, Eugene Kirpichov wrote:
It defines types like {{Int,Word}{16,32,64},Double,Float}{LE,BE} (for
example Int32BE) etc. with a corresponding Storable instance.
How about type constructors LittleEndian and BigEndian?
newtype LittleEndian a = LittleEndian a
Maybe using some type classes you can even get rid of Template Haskell and
get plain Haskell 98?
Yes, I think you could have (given a module Data.Storable.LittleEndian as
LE)
instance LE.Storable a = Storable (LittleEndian a) where
sizeOf (LittleEndian a) = sizeOf a
alignment (LittleEndian a) = alignment a
peek p = fmap LittleEndian $ LE.peek p
poke p (LittleEndian a) = LE.poke p a
class LE.Storable a where
LE.peek :: Ptr a - IO a
LE.poke :: Ptr a - a - IO ()
instance LE.Storable Word16 where
LE.peek p = getWord16le (castPtr p)
LE.poke p = putWord16le (castPtr p)
...
I find this much cleaner and simpler to extend to other types.
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Re: [Haskell-cafe] Why is Haskell flagging this?
see also: http://hackage.haskell.org/packages/archive/mtl/latest/doc/html/Control-Monad-State-Lazy.html#v:state On 22 December 2010 20:02, Ryan Ingram ryani.s...@gmail.com wrote: Interesting. In that case, state f = StateT $ \s - Identity (f s) allows state to replace State in that code. Ozgur ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] $ do?
-BEGIN PGP SIGNED MESSAGE-
Hash: SHA1
On 12/15/10 02:36 , Roman Cheplyaka wrote:
Regarding the rationale, I'm not so sure and I'd like to hear an
explanation from someone competent. But I assume it has something
to do with the fact that if you supply a 'do' argument, you cannot
supply any more arguments (because 'do' extends to the right as far as
possible). Not that I'm convinced that it is a valid reason to prohibit
such construct.
Hm? do {...} would work, as would using indentation per usual layout rules
(the next argument would be indented no farther than the do). It'd
certainly be more confusing to read, though.
- --
brandon s. allbery [linux,solaris,freebsd,perl] allb...@kf8nh.com
system administrator [openafs,heimdal,too many hats] allb...@ece.cmu.edu
electrical and computer engineering, carnegie mellon university KF8NH
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Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/
iEYEARECAAYFAk0SsvUACgkQIn7hlCsL25XM6wCcDvu9G3fc9M5Vv6d2EKZ64X8t
k7YAn0hvoyq0KpmAAEyAD4HIWX8HsMTY
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Re: [Haskell-cafe] Behaviour of System.Directory.getModificationTime
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 On 12/17/10 06:22 , Arnaud Bailly wrote: Thanks for your answers. I am a little bit surprised, I thought timestamps were on the milliseconds scale. POSIX timestamps are seconds. - -- brandon s. allbery [linux,solaris,freebsd,perl] allb...@kf8nh.com system administrator [openafs,heimdal,too many hats] allb...@ece.cmu.edu electrical and computer engineering, carnegie mellon university KF8NH -BEGIN PGP SIGNATURE- Version: GnuPG v2.0.10 (Darwin) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAk0Ss28ACgkQIn7hlCsL25XpygCgziZm1KyO+dP00ACtIrfsueJg 0dQAoI6hNz3oSmiIO2kAiXtRmowWwAg1 =wAHu -END PGP SIGNATURE- ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] parsec2 vs. parsec3... again
Yeah, I know this has been discussed a number of times, but I have some concrete questions I haven't seen asked before. And the parsec 3 is now as fast as parsec 2 thing I've seen around doesn't seem to be true for me. I have an app that does a lot of parsing of small expressions. It's currently parsec2 operating on lots of little Texts (after an unpack, of course). A few parsing functions show up near the top of the profile output, so I thought an obvious improvement would be to parse Text directly and avoid the overhead and garbage of unpacking. Since parsec3 is now supposed to be as fast as parsec2 I thought I would give it a try. Parsec3 is 3.1.0, parsec 2 is 2.1.0.1: parsec2, String: total time = 10.66 secs (533 ticks @ 20 ms) total alloc = 2,340,113,404 bytes (excludes profiling overheads) parsec3, String: (this is just after upgrading the library and editing it to fix breakage from Parser being a type alias now) total time = 13.76 secs (688 ticks @ 20 ms) total alloc = 2,706,625,256 bytes (excludes profiling overheads) parsec3, Text: (wrote a Text instance similar to the one for ByteString, updated imports, no longer unpacking to String) total time = 15.96 secs (798 ticks @ 20 ms) total alloc = 3,338,005,896 bytes (excludes profiling overheads) This is not very encouraging! Especially strange is how Text generates *more* allocation... I'd expect less since it doesn't unpack all the Texts. The parsing functions are no longer at the top of the profile, but there are new 'unParser' and 'parsecMap' and 'parserBind' up at or near the top. 'unParser' just looks like it's unwrapping the Parsec newtype, so I don't fully understand how it's the most expensive, but it's called on every bind so it does get called a lot. There are no obvious super expensive ones, just lots and lots of them that add up. Parsec 3's unParser covers up the parsing function I wrote, so it's now hard to tell what the expensive parsing function actually is. I've seen a few remarks that you can't just throw together parsers and expect them to be fast, you have to profile them, but nothing on how to actually interpret the results of profiling. For instance, here's one of the main expensive parsers: p_unsigned_float :: P.CharParser st Double p_unsigned_float = do i - P.many P.digit f - P.option (P.char '.' P.many1 P.digit) if (null i null f) then P.pzero else do let int = List.foldl' (\total c - 10 * total + fromIntegral (Char.digitToInt c)) 0 i frac = foldr (\c total - (total + fromIntegral (Char.digitToInt c)) / 10) 0 f return (int + frac) There's an obvious problem where I get the digits as a String and then parse that with list functions, but I can't see any way to get parsec to return a chunk of Text. This is roughly how parsec itself parses numbers, in Text.Parsec.Token. So, my current options are either figure out some way to speed up parsec3+Text, revert to parsec2+String and give up, or try an entirely different parsing library. I've heard attoparsec is fast but I'd have to switch to utf8 bytestring which is a big change, and Text seems like the more correct choice anyway. Any ideas or experience? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Why is Haskell flagging this?
Thanks for the tip, Ozgur. It worked for me. Is this what you had in mind, Ryan? Michael == import Control.Monad.State.Lazy import Control.Monad import System.Random type GeneratorState = State StdGen data Craps a = Roll a | Win a | Lose a deriving (Show) genRandomR :: Random a = (a,a) - GeneratorState a genRandomR = state . randomR rollDie :: GeneratorState Int rollDie = genRandomR (1,6) roll2Dice :: GeneratorState Int roll2Dice = liftM2 (+) rollDie rollDie f :: Craps [Int] - GeneratorState (Craps [Int]) f (Roll []) = do g0 - get let (throw1,g1) = runState roll2Dice g0 put g1 case throw1 of 2 - return (Lose [throw1]) 3 - return (Lose [throw1]) 7 - return (Win [throw1]) 11 - return (Win [throw1]) _ - do g1 - get let (throw2,g2) = runState roll2Dice g1 put g2 if throw2 == throw1 then do return (Win [throw1,throw2]) else if throw2 == 7 then do return (Lose [throw1,throw2]) else do f (Roll [throw1,throw2]) f (Roll z@(throw1:throws)) = do g0 - get let (throw,g1) = runState roll2Dice g0 put g1 if throw == throw1 then do return (Win (z ++ [throw])) else if throw == 7 then do return (Lose (z ++ [throw])) else do f (Roll (z ++ [throw])) --- On Wed, 12/22/10, Ozgur Akgun ozgurak...@gmail.com wrote: From: Ozgur Akgun ozgurak...@gmail.com Subject: Re: [Haskell-cafe] Why is Haskell flagging this? To: Ryan Ingram ryani.s...@gmail.com Cc: haskell-cafe@haskell.org, Daniel Fischer daniel.is.fisc...@googlemail.com Date: Wednesday, December 22, 2010, 7:37 PM see also: http://hackage.haskell.org/packages/archive/mtl/latest/doc/html/Control-Monad-State-Lazy.html#v:state On 22 December 2010 20:02, Ryan Ingram ryani.s...@gmail.com wrote: Interesting. In that case, state f = StateT $ \s - Identity (f s) allows state to replace State in that code. Ozgur -Inline Attachment Follows- ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] UTF-8 in Haskell.
Hi, Recently, I am reading ssh hackage (http://hackage.haskell.org/package/ssh). When at the part of deal with string, I got confused. I am not sure if this is a bug for the hackage, or I am just misunderstanding. An ascii char takes a Word8. So this works (LBS stands for Data.ByteString.Lazy): toLBS :: String - LBS.ByteString toLBS = LBS.pack . map (fromIntegral . fromEnum) But a UTF-8 char takes a Int (Word32). Then I think the above code would break the data, right? If so, OK, then I think I could make a packInt which turns an Int into 4 Word8 first. Thus under all situation (ascii, UTF-8, or even UTF-32), my program always send 4 bytes through the network. Is that OK? -- 竹密岂妨流水过 山高哪阻野云飞 ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] ANN: cabal-dev 0.7.3.1 -- now with ghci!
Cabal-dev is now capable of launching ghci with the project's package database and local modules (if the package under development exposes a library). For example: # First, invoke cabal-dev install the package to populate the # package database: $ cabal-dev install snip $ cabal-dev ghci GHCi, version 6.12.3: http://www.haskell.org/ghc/ :? for help Loading package ghc-prim ... linking ... done. Loading package integer-gmp ... linking ... done. Loading package base ... linking ... done. Loading package ffi-1.0 ... linking ... done. Prelude The ghci shell should have access to all the libraries your application/library is using, as well as any modules that your library exposes. Note that this is not quite as natural as your traditional ghci shell, namely: Source modifications are not visible without exiting, re-issuing `cabal-dev install` *and* `cabal-dev ghci`. This will eventually get better, but that's where things are right now. The reason for this is that `cabal-dev ghci` just issues ghci with the cabal-dev package database (and excluding the user package db, to best reflect what cabal-dev does when it causes compilation). Cabal-dev is available on hackage and github: - http://hackage.haskell.org/package/cabal-dev - https://github.com/creswick/cabal-dev There is a short write-up with a (slightly) longer example here: - http://blog.ciscavate.org/2010/12/cabal-dev-sandboxing-your-haskell-development-and-now-with-ghci.html --Rogan smime.p7s Description: S/MIME Cryptographic Signature ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] UTF-8 in Haskell.
On Dec 22, 2010, at 9:29 PM, Magicloud Magiclouds wrote: Thus under all situation (ascii, UTF-8, or even UTF-32), my program always send 4 bytes through the network. Is that OK? Generally, no. Haskell strings are sequences of Unicode characters. Each character has an integral code point value, from 0 to 0x10, but technically, the code point itself is just a number, not a pattern of bits to be exchanged. That is an encoding. In any protocol you need know the encoding before you exchange characters as bytes or words. In some protocols it is implicit, in others explicit in header or meta data, and in yet others (IRC comes to mind) it is undefined (which makes problems for the user). The UTF-8 encoding uses a variable number of bytes to represent each character, depending on the code point, not Word32 as you suggested. Converting from Haskell's String to various encodings can be done with either the text package or utf8-string package. - Mark ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] UTF-8 in Haskell.
On Thu, Dec 23, 2010 at 2:01 PM, Mark Lentczner ma...@glyphic.com wrote: On Dec 22, 2010, at 9:29 PM, Magicloud Magiclouds wrote: Thus under all situation (ascii, UTF-8, or even UTF-32), my program always send 4 bytes through the network. Is that OK? Generally, no. Haskell strings are sequences of Unicode characters. Each character has an integral code point value, from 0 to 0x10, but technically, the code point itself is just a number, not a pattern of bits to be exchanged. That is an encoding. In any protocol you need know the encoding before you exchange characters as bytes or words. In some protocols it is implicit, in others explicit in header or meta data, and in yet others (IRC comes to mind) it is undefined (which makes problems for the user). The UTF-8 encoding uses a variable number of bytes to represent each character, depending on the code point, not Word32 as you suggested. Converting from Haskell's String to various encodings can be done with either the text package or utf8-string package. - Mark I see. I just realize that, in this case (ssh), I could use CString to avoid all problems about encoding. -- 竹密岂妨流水过 山高哪阻野云飞 ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
