October 2003 - Glasgow-haskell-users

Performance Tests in Haskell
by Andreas.Schroeder＠gillardon.de 16 Oct '03

16 Oct '03

Hi all, i have changed the compilation flags and the codes as you said. It seems to me that it worked, since the runtime of my test stabilized at 2002ns. Before, i got sometimes 4004ns. The bigger runtime part is now (as far as i can guess, see below why) the screen output. That brings me to two issues for performance tests in Haskell: 1. how can i do performance tests if the tests are small? In imperative languages, you cycle through 1000 times and divide the runtime by 1000. How can i do something similar in haskell? 2. How do i get haskell to do something _without_ printing anything on the screen? For now, i do something like main = do startt <- getCPUTime putStr $ (show testAIBD1) ++ ", " ++ (show testZins1) endt <- getCPUTime putStr $ "\tTook " ++ (show $ (endt - startt) `div` ((10^6) * 5)) ++ " ns\n" where testAIBD1 is a sum of 40 calculation results and also is testZins1. Another issue: with foreign C calls i have the problem to link automatically. i type something like > ghc --make Main.hs -fglasgow-exts -O2 -fliberate-case-threshold100 -funbox-strict-fields -fvia-C while having compiled the external C HAIBDUtil.c with HAIBDUtil.h to HAIBDUtil.o. As result, i get Chasing modules from: Main.hs Compiling AIBD ( AIBD.hs, ./AIBD.o ) Compiling Main ( Main.hs, ./Main.o ) Linking ... AIBD.o(.text+0x11e0):ghc1052.hc: undefined reference to `caibd' shure, "caibd" is the called C procedure from AIBD. well then, i type > ghc Main.o AIBD.o HAIBDUtil.o -o HAIBD.exe then everything is fine, and i get my executable. Now i wanted to profile, and added the options "-prof --auto-all" to the first ghc command. When trying to link, i get lot's of undefined references: > ghc Main.o AIBD.o HAIBDUtil.o -o HAIBD.exe AIBD.o(.text+0x425):ghc1364.hc: undefined reference to `CC_LIST' AIBD.o(.text+0x430):ghc1364.hc: undefined reference to `CC_LIST' AIBD.o(.text+0x439):ghc1364.hc: undefined reference to `CC_ID' AIBD.o(.text+0x444):ghc1364.hc: undefined reference to `CC_ID' (...) AIBD.o(.text+0x5fc):ghc1364.hc: undefined reference to `CCCS' AIBD.o(.text+0x605):ghc1364.hc: undefined reference to `CCCS' AIBD.o(.text+0x626):ghc1364.hc: undefined reference to `PushCostCentre' (...) Obviously (see "PushCostCentre" as last misssing reference), something for profiling is missing. What is it? Regards, Andreas Schroeder |---------+-----------------------------------------> | | Andreas.Schroeder(a)gillardon.de| | | Gesendet von: | | | glasgow-haskell-users-bounces@| | | haskell.org | | | | | | | | | 16.10.2003 09:37 | | | | |---------+-----------------------------------------> >-------------------------------------------------------------------------------------------------------------------| | | | An: glasgow-haskell-users(a)haskell.org | | Kopie: chak(a)cse.unsw.edu.au | | Thema: Re: GHC with MS .Net 2003 C compiler | >-------------------------------------------------------------------------------------------------------------------| Hi all, hi Manuel, thanks for the help. Yes, i read the user docs for "earlier, faster, thriftier, smaller ..." or a permutation of this, but i do not _really_ remember from my university time what strict functions are. Is by strict meant as in Formal OO that a function is trict iff its result is _|_ iff any of its arguments is _|_ ? I will try to use data Genauigkeit = Absolut {wert, intervall :: !Double} | Intervall !Double is that what you meant? I will read the strictness flag documentation. Thanks for the hints. Regards, Andreas Schroeder |---------+-----------------------------------------> | | Manuel M T Chakravarty | | | <chak(a)cse.unsw.edu.au> | | | Gesendet von: | | | glasgow-haskell-users-bounces@| | | haskell.org | | | | | | | | | 16.10.2003 07:02 | | | Bitte antworten an chak | | | | |---------+-----------------------------------------> > -------------------------------------------------------------------------------------------------------------------| | | | An: Andreas.Schroeder(a)gillardon.de | | Kopie: glasgow-haskell-users(a)haskell.org | | Thema: Re: GHC with MS .Net 2003 C compiler | > -------------------------------------------------------------------------------------------------------------------| Andreas.Schroeder(a)gillardon.de wrote, Generally, did you look at http://haskell.org/ghc/docs/latest/html/users_guide/faster.html > module AIBD(aibd, rechneZins, rechneRate, rechneKapital) where > import Foreign(unsafePerformIO) > > type Funktion = Double -> Double > > data Genauigkeit = Absolut {wert, intervall :: Double} > | Intervall Double See the paragraph under "Use strictness annotations" on the above web page on how to use strictness annotations to speed this data type up. > istOk :: Genauigkeit -> Double -> Double -> Bool > istOk (Absolut w i) x _ = abs (x-w) <= i > istOk (Intervall i) _ dx = abs dx <= i > > sekantenVerfahren :: Funktion -> Genauigkeit -> Genauigkeit -> Int -> > Double -> Double > sekantenVerfahren f gx gy tiefe start = sekantenIter f tiefe gx gy x1 x2 y1 > y2 where > x1 = start > x2 = start + start * 0.1 > y1 = f x1 > y2 = f x2 > sekantenIter _ 0 _ _ _ x2 _ _ = x2 > sekantenIter f tiefe gx gy x1 x2 y1 y2 = > let > x3 = x2 - y2 * (x2 - x1) / (y2 - y1) > y3 = f x3 > dy = y3 - y2 > dx = x3 - x2 > in > if (istOk gx x3 dx) && (istOk gy y3 dy) then x3 > else sekantenIter f (tiefe-1) gx gy x2 x3 y2 y3 Code like this may benefit from using the option "-O2" and possibly also "-fliberate-case-threshold100" http://haskell.org/ghc/docs/latest/html/users_guide/flag-reference.html#AEN… > foreign import ccall "HAIBDUtil.h caibd" caibd :: Double -> Double -> > Double -> Int -> IO Double > > aibd:: Double -> Double -> Double -> Int -> Double > aibd kapital zins rate jahre = unsafePerformIO (caibd kapital zins rate > jahre) > {- > does the same than > aibd:: Double -> Double -> Double -> Int -> Double > aibd kapital _ _ 0 = kapital > aibd kapital zins rate jahre = aibd (kapital + kapital * zins - rate) > zins rate (jahre-1) > -} Two comments with -O2 -fliberate-case-threshold100 the Haskell version may be as fast as the C version. If not, better foreign import as a pure functions foreign import ccall "HAIBDUtil.h caibd" caibd :: Double -> Double -> Double -> Int -> Double and omit the unsafePerformIO. Cheers, Manuel _______________________________________________ Glasgow-haskell-users mailing list Glasgow-haskell-users(a)haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users _______________________________________________ Glasgow-haskell-users mailing list Glasgow-haskell-users(a)haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users

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Re: GHC with MS .Net 2003 C compiler
by Andreas.Schroeder＠gillardon.de 16 Oct '03

16 Oct '03

Hi all, hi Manuel, thanks for the help. Yes, i read the user docs for "earlier, faster, thriftier, smaller ..." or a permutation of this, but i do not _really_ remember from my university time what strict functions are. Is by strict meant as in Formal OO that a function is trict iff its result is _|_ iff any of its arguments is _|_ ? I will try to use data Genauigkeit = Absolut {wert, intervall :: !Double} | Intervall !Double is that what you meant? I will read the strictness flag documentation. Thanks for the hints. Regards, Andreas Schroeder |---------+-----------------------------------------> | | Manuel M T Chakravarty | | | <chak(a)cse.unsw.edu.au> | | | Gesendet von: | | | glasgow-haskell-users-bounces@| | | haskell.org | | | | | | | | | 16.10.2003 07:02 | | | Bitte antworten an chak | | | | |---------+-----------------------------------------> >-------------------------------------------------------------------------------------------------------------------| | | | An: Andreas.Schroeder(a)gillardon.de | | Kopie: glasgow-haskell-users(a)haskell.org | | Thema: Re: GHC with MS .Net 2003 C compiler | >-------------------------------------------------------------------------------------------------------------------| Andreas.Schroeder(a)gillardon.de wrote, Generally, did you look at http://haskell.org/ghc/docs/latest/html/users_guide/faster.html > module AIBD(aibd, rechneZins, rechneRate, rechneKapital) where > import Foreign(unsafePerformIO) > > type Funktion = Double -> Double > > data Genauigkeit = Absolut {wert, intervall :: Double} > | Intervall Double See the paragraph under "Use strictness annotations" on the above web page on how to use strictness annotations to speed this data type up. > istOk :: Genauigkeit -> Double -> Double -> Bool > istOk (Absolut w i) x _ = abs (x-w) <= i > istOk (Intervall i) _ dx = abs dx <= i > > sekantenVerfahren :: Funktion -> Genauigkeit -> Genauigkeit -> Int -> > Double -> Double > sekantenVerfahren f gx gy tiefe start = sekantenIter f tiefe gx gy x1 x2 y1 > y2 where > x1 = start > x2 = start + start * 0.1 > y1 = f x1 > y2 = f x2 > sekantenIter _ 0 _ _ _ x2 _ _ = x2 > sekantenIter f tiefe gx gy x1 x2 y1 y2 = > let > x3 = x2 - y2 * (x2 - x1) / (y2 - y1) > y3 = f x3 > dy = y3 - y2 > dx = x3 - x2 > in > if (istOk gx x3 dx) && (istOk gy y3 dy) then x3 > else sekantenIter f (tiefe-1) gx gy x2 x3 y2 y3 Code like this may benefit from using the option "-O2" and possibly also "-fliberate-case-threshold100" http://haskell.org/ghc/docs/latest/html/users_guide/flag-reference.html#AEN… > foreign import ccall "HAIBDUtil.h caibd" caibd :: Double -> Double -> > Double -> Int -> IO Double > > aibd:: Double -> Double -> Double -> Int -> Double > aibd kapital zins rate jahre = unsafePerformIO (caibd kapital zins rate > jahre) > {- > does the same than > aibd:: Double -> Double -> Double -> Int -> Double > aibd kapital _ _ 0 = kapital > aibd kapital zins rate jahre = aibd (kapital + kapital * zins - rate) > zins rate (jahre-1) > -} Two comments with -O2 -fliberate-case-threshold100 the Haskell version may be as fast as the C version. If not, better foreign import as a pure functions foreign import ccall "HAIBDUtil.h caibd" caibd :: Double -> Double -> Double -> Int -> Double and omit the unsafePerformIO. Cheers, Manuel _______________________________________________ Glasgow-haskell-users mailing list Glasgow-haskell-users(a)haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users

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reexport warnings
by Serge D. Mechveliani 16 Oct '03

16 Oct '03

Dear GHC and Haskell experts, I need advice on the following question. My application program (called DoCon), being ported recently to ghc-6.0.1, needs to provide the user (program) with the following visibility scope of items: all the proper DoCon export + most of Haskell standard library + FiniteMap, and maybe some others (please, help FiniteMap, Set to become standard!). What is the best way to organize this? I arrange this by reexporting a large part of Haskell library from certain particular DoCon module DExport. This is put so because most mathematician users are lazy to search among proper Haskell libraries: they had already imported DoCon+(Haskell library) from DoCon, and do not want to search any more among List, Ratio, etc. -------------------------------------------------------------- module DExport -- All the export of DoCon + part of GHC exploited by DoCon. -- -- Set the line import DExport -- -- if you are lazy to find more precisely which modules your -- program needs. (module DPrelude, module Categs, ... -- DoCon proper export ... module Data.FiniteMap, module Prelude, module List, module Ratio, module Random ) where import Data.FiniteMap import List hiding (minimum, maximum, sort, sortBy) import Prelude hiding (minimum, maximum, ) import Ratio import Random import DPrelude -- DoCon proper import ... ------------------------------------------------- Is this a reasonable way to arrange the thing? Now, the ghc-6.0.1 compiler reports Compiling DExport ... Warning: `++' is exported by `module Prelude' and `module List' .. Warning: `foldr' is exported by `module Prelude' and `module List' .. Warning: `concat' is exported by `module Prelude' and `module List' ... I think that these overlaps are harmless, and the compiler will still set the intended definitions for (++), foldr, etc., without any danger. Aslo proper DoCon export fron DExport has many similar overlaps. I think that it is often useful to be able to import an item from different modules. Is this reasonable? Generally, I accept these overlap warnings as useful ones. But at the installation, such strange numerous warnings on DExport will frighten the user. Therefore, Makefile has, probably, to compile the last module DExport with this kind of messages switched off. Right? Thank you in advance for your advice. Answer, please, to mechvel(a)botik.ru ----------------- Serge Mechveliani mechvel(a)botik.ru

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Re: overlapping instances
by Arie Peterson 15 Oct '03

15 Oct '03

>What would have GHC do for the "convert :: String -> String" case? >(You'd like "convert = id" here but it's not clear to me what the >general rule should be.) > > mike The general rule should be that convert :: a -> a = id, no matter what other instances are available. Is there any way to tell GHC so? It would be nice to be able to define 'precedences'. Arie

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overlapping instances
by Arie Peterson 15 Oct '03

15 Oct '03

Hi all, In an attempt to design a elegant way to serialise things to any serialised form, I came up with the following exotic solution: ### {-# OPTIONS -fallow-undecidable-instances -fallow-overlapping-instances #-} module Convertable where class Convertable a b where convert :: a -> b instance Convertable a a where convert = id instance (Convertable a b,Convertable b c) => Convertable a c where convert = (convert :: b -> c) . (convert :: a -> b) class (Convertable a b,Convertable b a) => Equivalent a b ### Happily surprised to see GHC swallow this, I continued by adding ### {-# OPTIONS -fallow-undecidable-instances -fallow-overlapping-instances #-} module Serialise where import Convertable import Data.PackedString (PackedString,packString,unpackPS) instance Convertable String PackedString where convert = packString instance Convertable PackedString String where convert = unpackPS instance (Show a) => Convertable a String where convert = show instance (Read a) => Convertable String a where convert = read ### But now GHC complains about overlapping instances: "Overlapping instance declarations: Serialise.hs:16: Convertable String a Convertable.hs:7: Convertable a a" Why can't GHC decide that the "Convertable String a" instance is more specific? Apparently, there is no problem with the combination of "Convertable a a" and "Convertable a String": if I leave out "read", all is well. What is the difference with the above? In the manual one can find: "GHC is also conservative about committing to an overlapping instance. For example: class C a where { op :: a -> a } instance C [Int] where ... instance C a => C [a] where ... f :: C b => [b] -> [b] f x = op x From the RHS of f we get the constraint C [b]. But GHC does not commit to the second instance declaration, because in a paricular call of f, b might be instantiate to Int, so the first instance declaration would be appropriate. So GHC rejects the program. If you add -fallow-incoherent-instances GHC will instead silently pick the second instance, without complaining about the problem of subsequent instantiations." I do not understand why GHC can't choose between C [Int] (whenever f is parametrised with Int) or C [a] (whenever f is parametrised with anything else). (While checking the type of f, it is clear that the constraint C [b] is always met.) (Adding -fallow-incoherent-instances did not change anything.) Thanks a lot for putting up with my English and my dubious type constructions :-). Regards, Arie Peterson BTW: I would like to use this opportunity to express my content: I think haskell is a wonderful language (never, ever anymore javascript :s) and GHC is a, uhm, glorious compiler :-).

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GHC Lexer
by Steffen Mazanek 15 Oct '03

15 Oct '03

Hello, to add a new keyword, say "struct" to the GHC, I have added ITstruct to data type Token in module Lex.lhs. Further on I have adapted ghcExtensionKeywordsFM. Is this already sufficient for lexing? In LexCore there is a function lexKeyword without a comment. It is called by lexer if the first character is %. What does this mean? Thank you, Steffen

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ghc-6.0.1 solaris 2.9 readline problem
by Matt Fairtlough 14 Oct '03

14 Oct '03

I've just installed the solaris2.8 binary package for ghc-6.0.1 I confess that I am running solaris2.9, which may be the cause of the problem, in which case I suppose I need to wait. But perhaps my problem is more general. I am trying to build HaLeX, a library for processing automata and regular expressions. I have readline.h and history.h in /usr/local/include/readline, so the following error message is puzzling to me: HaLeX:make ghc --make -I./src -i./src -package util -O2 ./src/Main.hs -o ./bin/halex Chasing modules from: ./src/Main.hs Compiling RegExp ( ./src/RegExp.hs, ./src/RegExp.o ) ./src/RegExp.hs:20: Warning: `RegExp' is exported by `RegExp' and `RegExp(..)' In file included from /tmp/ghc18853.hc:6: /home/matt/lib/ghc-6.0.1/include/HsReadline.h:5: readline/readline.h: No such file or directory /home/matt/lib/ghc-6.0.1/include/HsReadline.h:6: readline/history.h: No such file or directory make: *** [halex] Error 1 I've searched for this issue but only found references to building ghc5 any help much appreciated. Matt. -- Matt Fairtlough Room 115 http://www.dcs.shef.ac.uk/~matt Verification and Testing Group m.fairtlough(a)dcs.shef.ac.uk Room 115, Dept. of Computer Science Tel: (0)114-22-21826 University of Sheffield Fax: (0)114-22-21810 Regent Court, 211 Portobello Street, Sheffield S1 4DP, UK

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GHC with MS .Net 2003 C compiler
by Andreas.Schroeder＠gillardon.de 14 Oct '03

14 Oct '03

Hi all, i am just evaluating Haskell (GHC) for the use in the company i work. I have done some performance tests with Haskell, Java and C++ for some finance mathematical algorithms (you know, some folks are addicted to performance - not i). Unfortunately, pure Haskell did not perform very well. I then used a hybrid solution with some foreing called C code (25 lines of C) to get some boost on performance after some profiling analysis on "where is all the time gone?". I don't know exactly why, but even with the optimize flags on, the hybrid haskell solution takes six times longer than the C++ version compiled with the MS .Net 2003 C++ compiler. This one is even three times faster than the cygwin C++ compiler itself. That's what made me think: could i use the MS .Net 2003 C compiler to get the GHC libraries object code and then link them with the generated C code from GHC compiled again with the MS compiler? If it's possible, how to? Can anyone anticipate a performance improvement (like i do - well, at least i hope)? Btw, if you're interested, java (JDK 1.4.2_01 Server JVM) takes twice the time of MS .Net compiled C++ for my test. If you want, i can also post the Haskell code i tested. Regards, Andreas Schroeder

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Haddock warnings for unresolved prelude functions
by Juanma Barranquero 10 Oct '03

10 Oct '03

I'm using Haddock 0.5, compiled for GHC 6.0.1, and I get warnings when "haddock"ing a simple module: Warning: module not found: Prelude Warning: MyModule: the following names could not be resolved: Prelude.[] Bool Eq I can see what's happening: I'm not passing Prelude.hs to Haddock, but I'm using pPrelude functions. But I don't want to pass it a Prelude.hs and don't want the warnings either. Is there any way to force it to be silent about unresolved Prelude functions? (I tried --no-implicit-prelude, but the warnings are still there). Thanks, /L/e/k/t/u

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getSignalMask ghc6.0.1
by Shawn P. Garbett 09 Oct '03

09 Oct '03

I'm trying to understand the ghc signal implementation. I can't do much with the provided examples, because getSignalMask exits the program with: Fail: invalid argument Action: getSignalMask Reason: Invalid argument I'm using FreeBSD 5.0 with ghc6.0.1. Is there any tutorials or explanations about posix signals/threads in ghc out there? Shawn

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