- Glasgow-haskell-users

RE: unsafeness of unsafeInterleaveIO
by Simon Marlow 13 Jun '05

13 Jun '05

On 11 June 2005 02:23, Remi Turk wrote: > On Sat, Jun 11, 2005 at 01:55:57AM +0200, Thomas Jäger wrote: >>> Just looking at the documentation for System.IO.unsafeInterleaveIO, >>> what exactly is unsafe about it? >> >> It can create "pure values" that trigger side effects during their >> evaluation. This can be abused to do IO outside of an IO monad >> (actually, hGetContents can already be used for that purpose). >> >> In the worst case, it can even crash the RTS: >>> import Control.Concurrent.STM >>> import System.IO.Unsafe >>> >>> main :: IO () >>> main = atomically =<< unsafeInterleaveIO (atomically $ return $ >>> return ()) >> >> Thomas > > Stares at a core-dump. > I wonder whether this would be worth a bug-report, or perhaps a > warning in STM's docs about (understandable) undefined behaviour > in this case. Interestingly, Tomasz Zielonka's FakeSTM [1] > survives it. Yes, the STM implementation can't cope with nested transactions - I noticed this once before when using unsafePerformIO. I'll see if it would be possible to raise an exception when a nested atomically is detected. Cheers, Simon

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unsafeness of unsafeInterleaveIO
by Andre Pang 11 Jun '05

11 Jun '05

G'day all, Just looking at the documentation for System.IO.unsafeInterleaveIO, what exactly is unsafe about it? -- % Andre Pang : trust.in.love.to.save <http://www.algorithm.com.au/>

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benchmarking 6.4 vs 5.02.3
by Serge D. Mechveliani 10 Jun '05

10 Jun '05

I wrote about ghc-5.02.1 taking 13 times less memory than ghc-6.4 to compute a certain example like merge-sort. Now, I compare ghc-5.02.3 and ghc-6.4 on the same machine. The needed time and memory occur the same all right. The resources grow almost as O(n*log(n)), as expected. My error was that it was -H used for 5.03 instead of -M. With -M, they need the same time and space. Sorry for confusion. ----------------- Serge Mechveliani mechvel(a)botik.ru

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5.02.3 built
by Serge D. Mechveliani 10 Jun '05

10 Jun '05

I managed to install ghc-5.02.3 i86x binary on recent Debian Linux. It required libreadline.so.3, and I linked it symbolically to existing libreadline.so.4.3, Similarly, libncurses.so.4 linked to higher. My docon-2.06 looks to build and run correct under all this. Now, we shall compare 6.4 to 5.02.3 ... ----------------- Serge Mechveliani mechvel(a)botik.ru

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RE: 5.02
by Simon Marlow 10 Jun '05

10 Jun '05

On 10 June 2005 11:36, Christian Maeder wrote: > Simon Marlow wrote: >> On 10 June 2005 08:58, Serge D. Mechveliani wrote: >> >>> Now, I indeed, intend to compare 6.4 to 5.02 on several examples, >>> downloaded ghc-5.02.3 and tried to make it with ghc-6.4 >> >> Yes, that's unlikely to work. > > I was able to install the binaries from ghc-5.04.2-1.i386.rpm (with > rpm2cpio though). I did not know that ghc-5.02.3 is exceptional. Is it > really? Not that I'm aware of, but in general compiling an old compiler with a new compiler isn't guaranteed to work. Old features or libraries that we used in 5.02 may have gone away, for example. > 6.4 produces better and faster code than 6.2.2 and 5.04.2 for our > application. Great! Cheers, Simon

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RE: 5.02
by Simon Marlow 10 Jun '05

10 Jun '05

On 10 June 2005 08:58, Serge D. Mechveliani wrote: > Now, I indeed, intend to compare 6.4 to 5.02 on several examples, > downloaded > ghc-5.02.3 and tried to make it with ghc-6.4 Yes, that's unlikely to work. Cheers, Simon

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runghc <- ghc
by Serge D. Mechveliani 10 Jun '05

10 Jun '05

I wrote recently about replacing "runghc configure" with "ghc -configure" and such. But I observe now `runhaskell' instead of `runghc' in docs on Cabal. I always wrote a typo runghc (probably, had copied it from somewhere), and it works! `runhaskell' may make difference to my suggestion, because some functionality may tend to have Haskell-wide command names ... I see. ----------------- Serge Mechveliani mechvel(a)botik.ru

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runghc <- ghc
by Serge D. Mechveliani 10 Jun '05

10 Jun '05

Dear GHC developers, Why do you introduce the runghc command for Cabal, while everyting is done by the `ghc' driver ? We have ghc -c ghc --make ... Cabal is a part of GHC. So, it is natural to continue: ghc -configure ghc -build ghc -install And the user would not need to deal with a new notion of `runghc'. With kind regards, ----------------- Serge Mechveliani mechvel(a)botik.ru

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5.02
by Serge D. Mechveliani 10 Jun '05

10 Jun '05

On Jun 09, 2005 Simon Marlow wrote: > On 09 June 2005 11:47, Serge D. Mechveliani wrote: > > >> A difference of 2.5Mb is really very small. If you could show that > >> the space usage is linear in one case and flat in another, then we > >> have a problem. > > > > But a ratio 2600 K / 200 K for n = 55000 is not so small. > > > > I never tested this, but what if in this mergeSort-like example the > > space sizes are > > space.6.4(n) = 13*space.5.02(n) > > > > (which has the above ratio for n = 55000) > > ? > > If you can demonstrate that GHC 6.4 uses 13 times more space than 5.02 > on your example, then that's a performance bug - but all you showed so > far is that 6.4 uses 2.5Mb more space. i.e. you need to do a few more > measurements for different values of n. I hope, this will be impossible to demonstrate. This measurement report for 55000 was stored several years ago. Now, I indeed, intend to compare 6.4 to 5.02 on several examples, downloaded ghc-5.02.3 and tried to make it with ghc-6.4 on recent Debian Linux. But it falied. It looks difficult to port 5.02.x to recent Debian Linux. ---------------------------------------------------- ---------------------------------------------------- ... ... > primop-primop-info.hs-incl ../../glafp-utils/mkdependC/mkdependC -f ... /usr/bin/ghc -M -optdep-f -optdep.depend ... -recomp -Rghc-timing -H16M -O utils/Bag.lhs utils/BitSet.lhs ... /StixPrim.lhs main/Config.hs rename/ParseIface.hs parser/Parser.hs main/ParsePkgConf.hs utils/FastTypes.lhs:41: warning: extra tokens at end of #else directive utils/FastTypes.lhs:62: warning: extra tokens at end of #endif directive ... nativeGen/MachMisc.lhs:72: unterminated argument list invoking macro "IF_ARCH_alpha" <<ghc: 147259508 bytes, 65 GCs, 2329439/5098104 avg/max bytes residency (4 samples), 20M in use, 0.06 INIT (0.00 elapsed), 1.60 MUT (6.64 elapsed), 0.33 GC (0.36 elapsed) :ghc>> make[2]: *** [depend] Error 1 make[1]: *** [boot] Error 1 make[1]: Leaving directory `/home/mechvel/ghc/5.02.3/ghc-5.02.3/ghc' make: *** [all] Error 1 ------------------------------------------------ ------------------------------------------------ ----------------- Serge Mechveliani mechvel(a)botik.ru

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RE: [Haskell] Template Haskell Question: Spliced expr. of type TypeQ
by Simon Peyton-Jones 09 Jun '05

09 Jun '05

[Redirecting to GHC users] I'm afraid I never got around to implementing splices in types, I'm afraid. Interestingly, you are the first person who's asked for them. I forget the details... it's not a massive job to implement them, but not trivial either. If this is important for other people too, feel free to let me know. Simon | -----Original Message----- | From: haskell-bounces(a)haskell.org [mailto:haskell-bounces@haskell.org] On Behalf Of Eike M. | Scholz(a)gmx.de | Sent: 06 June 2005 23:10 | To: haskell(a)haskell.org | Subject: [Haskell] Template Haskell Question: Spliced expr. of type TypeQ | | Hi, | | maybe someone can help me with this: | | I was wandering if I could do something similar to Depended Types | using Template-Haskell. The documentation of GHC (6.2.2 and | 6.4) says that a splice may occur in place of a type, but I | get a parse error when I try that. | | So here is what I did: | | made a Module Templates: | | module Templates where | | expr = [| 1337*7331 |] | decl = [d| hello = putStr "Hello\n"|] | ty = [t| Int |] | | | and made test file: | | import Templates | | $(decl) -- works well (tested with ghci) | | e = $(expr) -- works also well | | i :: ($tyr) -- gives a parse error | i = 1 | | | I would be really happy if someone knows how to make the last example | must be written, or if that works at all. (If not, maybe the | Documentation should get updated) | | and thanks you for reading this posting, anyway. | | -- Eike | | _______________________________________________ | Haskell mailing list | Haskell(a)haskell.org | http://www.haskell.org/mailman/listinfo/haskell

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