Re: [Haskell-cafe] Can i split a String by its element ?
:hoogle splitOn No results found :m + Data.Text splitOn , 2,15,33,0,8,1,16,18 interactive:1:8: Couldn't match expected type `Text' against inferred type `[Char]` ... :i splitOn splitOn :: Text - Text - [Text] -- Defined in Data.Text It seems this splitOn is not one used by you ? - e^(π.i) + 1 = 0 -- View this message in context: http://haskell.1045720.n5.nabble.com/Can-i-split-a-String-by-its-element-tp3395066p3396513.html Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] `cabal install darcs` fail !
cabal update cabal install darcs .. Installing library in /home/sw2wolf/.cabal/lib/hashed-storage-0.5.5/ghc-6.10.4 Registering hashed-storage-0.5.5... Reading package info from dist/installed-pkg-config ... done. Writing new package config file... done. cabal: Error: some packages failed to install: darcs-2.5.1 depends on haskeline-0.6.3.2 which failed to install. haskeline-0.6.3.2 failed during the configure step. The exception was: ExitFailure 1 uname -a FreeBSD mybsd.zsoft.com 8.1-RELEASE FreeBSD 8.1-RELEASE #1: Wed Sep 8 09:07:54 CST 2010 r...@mybsd.zsoft.com:/media/G/usr/obj/media/G/usr/src/sys/MYKERNEL i386 It seems that the cabal is NOT very strong, isnot it ? - e^(π.i) + 1 = 0 -- View this message in context: http://haskell.1045720.n5.nabble.com/cabal-install-darcs-fail-tp3390542p3390542.html Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] The type data constructor confused me !
data Layout a = forall l. (LayoutClass l a, Read (l a)) = Layout (l a) readsLayout :: Layout a - String - [(Layout a, String)] readsLayout (Layout l) s = [(Layout (asTypeOf x l), rs) | (x, rs) - reads s] Why is the first parameter of readsLayout (Layout l) not Layout (l a) ? Sincerely! - e^(π.i) + 1 = 0 -- View this message in context: http://haskell.1045720.n5.nabble.com/The-type-data-constructor-confused-me-tp3339226p3339226.html Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] How to write such a code elegantly ?
betterStdGen :: IO StdGen betterStdGen = alloca $ \p - do h - openBinaryFile /dev/urandom ReadMode hGetBuf h p $ sizeOf (undefined :: Int) hClose h mkStdGen $ peek p picoSec :: IO Integer picoSec = do t - ctPicosec `liftM` (getClockTime = toCalendarTime) return t The pseudo-code is : if doesFileExist /dev/urandom then myGen = betterStdGen else myGen = (mkStdGen . fromTnteger) $ picoSec How to write these pseudo-code elegantly ? Sincerely! - e^(π.i) + 1 = 0 -- View this message in context: http://haskell.1045720.n5.nabble.com/How-to-write-such-a-code-elegantly-tp3334329p3334329.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] How to write such a code elegantly ?
thanks for all of your replies. I will test your code later. Another newbie question is why has the following code indentation problem ? rollDice n = do let myGen = if doesFileExist /dev/urandom then betterStdGen else (mkStdGen . fromInteger) $ picoSec return $ (take 1 $ randomRs (1,n) myGen) !! 0 Sincerely! - e^(π.i) + 1 = 0 -- View this message in context: http://haskell.1045720.n5.nabble.com/How-to-write-such-a-code-elegantly-tp3334329p3334379.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] How to write such a code elegantly ?
rollDice n = do tmp - doesFileExist /dev/urandom myGen - if tmp then betterStdGen else (mkStdGen . fromInteger) $ picoSec return $ (take 1 $ randomRs (1,n) myGen) !! 0 works but not so elegant? - e^(π.i) + 1 = 0 -- View this message in context: http://haskell.1045720.n5.nabble.com/How-to-write-such-a-code-elegantly-tp3334329p3334395.html Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] What's the best seed for random API ?
picoSec :: IO Integer picoSec = do t - ctPicosec `liftM` (getClockTime = toCalendarTime) return t rollDice :: Int - IO Int rollDice n = do ps - picoSec return $ (take 1 $ randomRs (1,n) $ mkStdGen $ fromInteger ps) !! 0 The above code uses `ctPicosec` as seed. Is it better to use the output of /dev/urandom as seed ? Sincerely! - e^(π.i) + 1 = 0 -- View this message in context: http://haskell.1045720.n5.nabble.com/What-s-the-best-seed-for-random-API-tp3329807p3329807.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] cannot install regex-posix using cabal ?
canot it be fixed ? - e^(π.i) + 1 = 0 -- View this message in context: http://haskell.1045720.n5.nabble.com/cannot-install-regex-posix-using-cabal-tp3301201p3307465.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] Beginners help
According to map's definition, we know the 'fs' should be a list of function. so 'p' need a [a-b] as its parameter.And the result of 'p' should be a list of function which accepts [a] and return [b]. So the type of 'p' is [a-b] - [[a] - [b]] hope i make it clear. - e^(π.i) + 1 = 0 -- View this message in context: http://haskell.1045720.n5.nabble.com/Beginners-help-tp3306796p3307470.html Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] cannot install regex-posix using cabal ?
%ghc-pkg list|grep -i regex regex-base-0.93.2 %cabal install regex-posix Resolving dependencies... Configuring regex-posix-0.94.4... Preprocessing library regex-posix-0.94.4... running dist/build/Text/Regex/Posix/Wrap_hsc_make failed command was: dist/build/Text/Regex/Posix/Wrap_hsc_make dist/build/Text/Regex/Posix/Wrap.hs cabal: Error: some packages failed to install: regex-posix-0.94.4 failed during the building phase. The exception was: ExitFailure 1 How can i fix such a problem ? - e^(π.i) + 1 = 0 -- View this message in context: http://haskell.1045720.n5.nabble.com/cannot-install-regex-posix-using-cabal-tp3301201p3301201.html Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] How to use Data.ByteString ?
Hi, friends the following function works well rollDice n = getStdRandom (randomR (1,n)) :: IO Int now i want to use /dev/random to produce better random number, but it doesnot work rollDice_t n = do hd - openFile /dev/random ReadMode v - B.hGet hd 1 return (v `mod` n) + 1 No instance for (Integral B.ByteString) arising from a use of `mod' at Money.hs:15:12-20 Possible fix: add an instance declaration for (Integral B.ByteString) In the first argument of `return', namely `(v `mod` n)' In the first argument of `(+)', namely `return (v `mod` n)' In the expression: return (v `mod` n) + 1 then how to use the ByteString properly ? Sincerely!___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] How to understand the fmap here ?
The following code snippets is from xmonad: -- Given a window, find the screen it is located on, and compute -- the geometry of that window wrt. that screen. floatLocation :: Window - X (ScreenId, W.RationalRect) --... rr - snd `fmap` floatLocation w Prelude :i fmap class Functor f where fmap :: (a - b) - f a - f b It seems it is different from the definition of fmap ? sincerely! 2009-05-05 z_axis ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] about logical computation
hi, friends I am a Haskell newbie however i like it very much. After starting learn haskell, i donot find the corresponding , | , ~, , logical computation of C language. Sincerely! -- z_axis 2008-09-29 ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
