- Glasgow-haskell-users

Transformational Patterns?
by Pete Kazmier 25 Jul '06

25 Jul '06

After reading the paper "Pattern Guards and Transformational Patterns" by Martin Erwig and Simon Peyton Jones, I'm left wondering about the status of transformational patterns? Can we expect to see these at some point in GHC? Or have they gone by the wayside in favor of some other alternative? When I had finished reading the paper, I was disappointed to find out that they were not implemented as I was convinced of the merits based on the arguments presented in the paper. Thanks, Pete [1] http://research.microsoft.com/~simonpj/Papers/pat.htm

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-fasm vs. -fvia-c
by Joel Reymont 25 Jul '06

25 Jul '06

On Jul 25, 2006, at 2:09 PM, Duncan Coutts wrote: > You can also cut compile times by compiling fewer non-core > libraries and > by using -fasm rather than -fvia-C. I heard recently that GHC does not generate code that gcc likes and so there's a push to improve asm generation. What stage is that push at? Do I cripple my GHC build in any way by using asm as opposed to via-c? Thanks, Joel -- http://wagerlabs.com/

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Internships on GHC and Haskell at MSR Cambridge
by Simon Peyton-Jones 25 Jul '06

25 Jul '06

Gentle Haskellers Would you be interested in working for three months at Microsoft Research, Cambridge, on a project related to GHC or Haskell? MSR Cambridge now takes interns *year-round*, not just in the summer months. Simon Marlow and I are keen to attract motivated and well-qualified folk to work with us on our research, and on improving or developing GHC. If you or one of your students is interested, you can find more details here http://hackage.haskell.org/trac/ghc/wiki/Internships Our next empty slot is the Oct-Dec period, but you are welcome to apply for some later period. Simon PJ PS: There are lots of other programming-language folk at MSR (F#, security, probabilistic languages...), and stuff beyond that (machine learning, systems and networks...); see http://research.microsoft.com/aboutmsr/labs/cambridge/

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Text.Regex.Posix regcomp
by Rich Fought 24 Jul '06

24 Jul '06

Hello, I have a server application that I am building using GHC 6.4 (yes, an update to 6.4.2 is on the horizon, but not in the immediate future - unless it fixes this problem :) ) under MSYS/MinGW. Things work pretty well, but under stress testing the app eventually throws a Windows memory access violation (c0000005) exception out of the exact same location in the regcomp function every time. When it occurs is not deterministic - it could be after 20 requests or 2000 (usually higher, though). Various Windows debuggers shows it as a memory read error. regcomp is called several times with each incoming request. I'm pretty sure it's not a multi-threading issue, as there is only one client sending requests over and over again. Can anyone suggest some ideas or debugging tips? TIA, Rich

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Data Parallel Haskell and GHC 6.5
by Joel Reymont 24 Jul '06

24 Jul '06

Folks, Do I still need to use the separate branches described at http:// www.cse.unsw.edu.au/~chak/project/dph/ to use Data Parallel Haskell and the Concurrent array library? Thanks, Joel -- http://wagerlabs.com/

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regex.h included with GHC 6.4.2
by Rich Fought 24 Jul '06

24 Jul '06

Am I crazy or is there an error in regex.h included with GHC? On line 110 there appears to be an extraneous or unterminated 'extern "C" {' Regards, Rich

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Re: Text.Regex.Posix regcomp
by Rich Fought 21 Jul '06

21 Jul '06

Thanks, upgrading to 6.4.2 seems to have done the trick. I've obviously put it off too long! Rich

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<<loop>> problems
by Chad Scherrer 20 Jul '06

20 Jul '06

Hi, I have some code that just says <<loop>> when it's run. I found a FAQ that says something about finalizers, but I'm not using those (at least not consciously). Here is my main: import qualified Data.ByteString.Lazy.Char8 as L main = do ls <- liftM L.lines $ L.readFile "output.txt" mapM_ (print . score . readUArray . L.words) ls ... and the types of some other pieces (I'm not sure how much you care to see) score :: (IArray a Double) => a Int Double -> Double readUArray :: [Data.ByteString.Lazy.ByteString] -> UArray Int Double Is this a bug, or am I doing something wrong? Thanks! -- Chad Scherrer "Time flies like an arrow; fruit flies like a banana" -- Groucho Marx

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Possible memory leak?
by Chris Kuklewicz 19 Jul '06

19 Jul '06

I was working on pulling library calling code from JRegex into Text.Regex.Lazy and I am wondering if this code for compiling regex.h regular expressions is a potential memory leak: > regcomp pattern flags = do > regex_fptr <- mallocForeignPtrBytes (#const sizeof(regex_t)) > r <- withCString pattern $ \cstr -> > withForeignPtr regex_fptr $ \p -> > c_regcomp p cstr (fromIntegral flags) > if (r == 0) > then do addForeignPtrFinalizer ptr_regfree regex_fptr > return (Regex regex_fptr) > else error "Text.Regex.Posix.regcomp: error in pattern" -- ToDo The (r/=0) path calls error, but never attaches the finalizer. And the man page for regex says: > The regfree() function frees any dynamically-allocated storage associated > with the compiled RE pointed to by preg. The remaining regex_t is no > longer a valid compiled RE and the effect of supplying it to regexec() or > regerror() is undefined. So it looks like the c_regcomp might allocate memory associated with regex_fptr even in the event of an error, so this case needs the same finalizer. I have not re-compiled GHC, but I have attached a small untested patch to change the code to always trigger the finalizer when there is an error: > regcomp pattern flags = do > regex_fptr <- mallocForeignPtrBytes (#const sizeof(regex_t)) > addForeignPtrFinalizer ptr_regfree regex_fptr > r <- withCString pattern $ \cstr -> > withForeignPtr regex_fptr $ \p -> > c_regcomp p cstr (fromIntegral flags) > if (r == 0) > then return (Regex regex_fptr) > else do finalizeForeignPtr regex_fptr > error "Text.Regex.Posix.regcomp: error in pattern" -- ToDo Cheers, Chris --- Text/Regex/Posix-orig.hsc 2006-07-18 11:06:55.000000000 +0100 +++ Text/Regex/Posix.hsc 2006-07-18 11:18:57.000000000 +0100 @@ -79,13 +79,14 @@ -> IO Regex -- ^ Returns: the compiled regular expression regcomp pattern flags = do regex_fptr <- mallocForeignPtrBytes (#const sizeof(regex_t)) + addForeignPtrFinalizer ptr_regfree regex_fptr r <- withCString pattern $ \cstr -> withForeignPtr regex_fptr $ \p -> c_regcomp p cstr (fromIntegral flags) if (r == 0) - then do addForeignPtrFinalizer ptr_regfree regex_fptr - return (Regex regex_fptr) - else error "Text.Regex.Posix.regcomp: error in pattern" -- ToDo + then return (Regex regex_fptr) + else do finalizeForeignPtr regex_fptr + error "Text.Regex.Posix.regcomp: error in pattern" -- ToDo -- ----------------------------------------------------------------------------- -- regexec

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Recompiling the darcs tree after a pull
by Joel Reymont 19 Jul '06

19 Jul '06

I get a lot of errors like this: utils/Panic.lhs:27:0: Failed to load interface for `Config': Bad interface file: stage1/main/Config.hi mismatched interface file versions: expected 6050, found 390518464 Do you guys always clean after a pull or is there an easy way to get a list of *.hi (and *.o) files to delete? Thanks, Joel -- http://wagerlabs.com/

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