- Glasgow-haskell-users

RE: DiffArray Performance
by Simon Marlow 03 Nov '03

03 Nov '03

> Hello again, > > Another thought.. > > Could it be that sTree0 is cyclic that accounts for this > dramatic slow down? I'm not to sure how DiffArray are > implemented, but if it's how I would do it it seems you > would end up with a massive chain of indirections. Possible. It is possible to get an O(n) slowdown by using DiffArrays, but only if you index the original array after making updates to it. If you use the array in a single-threaded way, then indexing should be O(1) and additionally update should be O(1) compared to O(n) for ordinary arrays. It's possible that your use of array here is being implemented as a sequence of updates, which will lead to highly suboptimal behaviour: > > > sTree0 :: STree > > > sTree0 = STree (array (0,9) [(n,(sTree0,[]))| n <- [0..9]]) I haven't checked the DiffArray implementation, though (it would be nice if someone could investigate DiffArray and fix any perf problems they find). Cheers, Simon

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RE: GHC and Kinds
by Simon Peyton-Jones 03 Nov '03

03 Nov '03

| type Kind = Type | | What does this mean? It means that Kinds are represented by Types. Admittedly, Kinds only use a small fragment of what Types can represent, namely Arrow, and type constructor applications. So * is represented by a TyConApp with a TyCon that is called typeCon. The really annoying thing about Kinds is that there's occasionally a bit of sub-kinding. In particular error :: forall a. String -> a We want to allow error "foo" :: Int# so the kind of 'a' can't be *, nor # (the kind of unboxed types). It's an "open" kind, written "?"; both * and # are sub-kinds of ?. You should nevertheless be able to encode your kind system in the same way as GHC does. But I have been thinking that it's over-kill to use Types for Kinds, and leads to no real saving. I may well split the two types in the future. Simon

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RE: mips64 and gmp observation
by Simon Marlow 03 Nov '03

03 Nov '03

> The same is true on IA64, if you look at the configure script there's > a little hack of mine... > > if test "$HaveLibGmp" = "NO"; then > if test "$HostArch_CPP" = "ia64"; then > AC_MSG_ERROR([You need to install libgmp (the in-tree version > does not work on IA64).]) > fi; > fi; > > It's probably broken for 64-bit architectures in general. I guess I should import a more up-to-date GMP at some point. Cheers, Simon

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RE: GHC changes
by Simon Marlow 03 Nov '03

03 Nov '03

> I have made some changes to the GHC source > code (6.0.1) and I would really welcome your > feedback, whether they are ok for my task > (first step: introduce record expressions > of the shape 'struct {x1=e1,x2=e2,...,xn=en}'): > > * added > > ("struct", ITstruct, bit glaExtsBit), > > to ghcExtensionKeywordsFM and > ITstruct to Token in Lex.lhs GHC's lexer is now based on an Alex specification, so this will be different in future GHCs. > 'struct' { ITstruct } > > to the token part of Parser.y (please tell me, why > in the lexer we declare ITstruct to represent > the keyword "struct" and in the parser specification > we turn back to 'struct'), In the parser 'struct' is just a token used in the grammar file, it doesn't represent an actual Haskell string. > How can I speed up the recompilation process? I just want to > check, whether my > changes are compilable or not, is it possible to switch off > optimization and > other time consuming transformations? You should definitely turn off optimisation when developing GHC. The Building Guide describes how to do this: http://www.haskell.org/ghc/docs/latest/html/building/building-guide.html Cheers, Simon

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RE: Question about profiling in GHC...
by Simon Marlow 03 Nov '03

03 Nov '03

> Yes, it's probably garbage collection. To be sure, you can > run your program > with the "-t" RTS option, which will create a file in the > current working > directory named "foo.stat" if the executable is named "foo". > The resulting > file will contain the total amount of time spent, the mutator > time, and the > GC time. (I recently ran into this problem myself...) The way we normally do this is to add '+RTS -sstderr' to the command line (avoids the pesky foo.stat file). Cheers, Simon

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RE: UArray question....
by Simon Marlow 03 Nov '03

03 Nov '03

> In GHC/FFI, is there some way (is it possible ?) to > access DIRECTLY an array of UArray type (immutable) in a > sequential contiguous memory buffer (in C side, for > example) without to need to copy the array elements one > by one ? GHC hackers and implementors are wellcome... :-) > My interest is to transmit the array over a network using > MPI, but avoiding marshalling overheads. > > It is easy to do this with StorableArray's in the IO > monad, of course, but I need to use UArray. I've been pondering this issue for a while. In fact, I have a replacement for StorableArray which addresses this issue, amongst others. I provide the following function: unsafeStorableArrayToIOUArray :: StorableArray i e -> IOUArray i e This function works in O(1) time in GHC's implementation, because it uses the same representation type for StorableArray and IOUArray (well, in my hacked version of StorableArray this is true). The function has an 'unsafe' prefix, because it only works when the representations of the two arrays are the same (currently true for all 'e' except Bool). >From an IOUArray, you can get a UArray by using unsafeFreeze. A better way might be to have an immutable StorableArray type, that you can get by freezing a StorableArray, and that also supports passing to C. This involves a lot of extra code, though. Cheers, Simon

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mips64-sgi-irix unreg success!
by dons＠cse.unsw.edu.au 02 Nov '03

02 Nov '03

Hey all, mips-sgi-irix builds and runs unregisterised from CVS! $ uname -a IRIX64 edison 6.5 07141529 IP30 mips $ ghc-inplace --version The Glorious Glasgow Haskell Compilation System, version 6.3 $ cat test.hs import System.Info main = do putStrLn System.Info.arch putStrLn System.Info.os $ ghc-inplace test.hs mipseb irix It runs the testsuite unregisterised, not to shabby for a weird box: OVERALL SUMMARY for test run started at Tue Oct 21 18:26:48 PDT 2003 1070 total tests, which gave rise to 1844 test cases, of which 0 caused framework failures 167 were skipped 1520 expected passes 14 expected failures 0 unexpected passes 143 unexpected failures I used the ports of GNU software that come with the "freeware" bundle for Irix, to save booting other software too. Use the following environment, at least on the above variety of mips machine: ghc-6.3 from cvs gcc-3.3 gmake-3.80 external libgmp Then: export MAKE=gmake export LDFLAGS=-L/usr/freeware/lib64 export CPPFLAGS=-I/usr/freeware/include export CFLAGS=-mabi=64 cat >> mk/build.mk <<END SRC_CC_OPTS+=-mabi=64 SRC_HC_OPTS+=-optc-mabi=64 -opta-mabi=64 -optl-mabi=64 SRC_CC_OPTS+=-L/usr/freeware/lib64 SRC_HC_OPTS+=-L/usr/freeware/lib64 END And you will have to comment out the vfork #define in libraries/base/cbits/{system.c,rawSystem.c}, as Irix vfork doesn't appear to be available without some other symbols being present. I will make a bindist available soon. Cheers, Don

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(no subject)
by andrew＠acooke.org 01 Nov '03

01 Nov '03

3 Importance: Normal a follow-up to close (hopefully) this thread. i couldn't repeat the error on other platforms (windows + rh9) and started to become suspicious that my system was unstable (it's been rock solid for years). first suspect was the kernel, but compiling a kernel triggered another error and then a bios warning - turns out that a fan has failed on the motherboard. so i guess that the memory problems are related to overheating (memcheck86 didn't detect any problems). no bug to report here. thanks for the help from various people via email. if anyone happens to know of a source of replacement chipset fans for AOpen mobos in S America I'd be grateful for a contact... ;-/ cheers, andrew andrew cooke said: > > no, i'm not sure it's segfaulting (i should have used a less specific > term), but i am seeing memory related errors. i've had messages in the > syslog that describes a null pointer passed to the kernel and i've also > just seen an error on stderr that says > > internal error: evacuate: strange closure type 39216 > Please report this as a bug to glasgow-haskell-bugs(a)haskell.org, > or http://www.sourceforge.net/projects/ghc/ > > the trouble is that when if first got the error with ghc5, i updated my > system. not only ghc, but also a slew of other packages. now i'm worried > that there are two different errors (one possibly related to X or > Mozilla), or even that ghc is merely the victim of an error in some other > program. > > i'm about to run the program on windows, using the parameters that gave > that message, to see if i can reproduce it. so far my attempts to > restrict the program scope and repeat the error have failed. > > once i'm a little clearer on what's happening i'll file a bug report. i > just wondered whether there was any way of getting the system to give more > informative errors when it dies (eg recompiling ghc in some kind of debug > mode). > > cheers, > andrew > > ps. just got a segmentation fault re-running the code that previously > gave the error above :o/ > > Volker Stolz said: > >> In local.glasgow-haskell-users, you wrote: >>> I have a ghc program that appears to be causing a memory error (either >>> segfaulting or tripping up X and killing my session). >> >> Are you sure it's segfaulting? You might simply run low on memory and >> your system starts killing processes to free up memory. >> Maybe you can find more details in the syslog. >> -- >> http://www-i2.informatik.rwth-aachen.de/stolz/ *** PGP *** S/MIME >> rage against the finite state machine >> >> > > > -- > http://www.acooke.org/andrew > _______________________________________________ > Glasgow-haskell-users mailing list > Glasgow-haskell-users(a)haskell.org > http://www.haskell.org/mailman/listinfo/glasgow-haskell-users > > -- http://www.acooke.org/andrew

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Useful info from crash?
by andrew cooke 01 Nov '03

01 Nov '03

Hi, I have a ghc program that appears to be causing a memory error (either segfaulting or tripping up X and killing my session). The program is rather disorganised, so I'm trying to reduce it to something more compact before submitting a report. Is there anything that would help me locate the source of the error so I know what to include/exclude, apart from trial and error? The error occured with both ghc5 (whatever is in debian stable) and 6.0.1 (again from debian package). Thanks, Andrew -- http://www.acooke.org/andrew

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Template Haskell...
by MR K P SCHUPKE 31 Oct '03

31 Oct '03

With reference to the future of template haskell - it would be nice if you could express the following: stringType :: String -> Q [Dec] stringType s = do x <- gensym "x" y <- gensym "y" return [ Newtype [] s [] (Constr s [(Strict,Tcon (TconName "String"))]) [], Proto ("show"++s) (Tapp (Tapp (Tcon Arrow) (Tcon (TconName s))) (Tcon (TconName "ShowS"))), Fun ("show"++s) [Clause [Pcon s [Pvar x]] (Normal (App (Var "showString") (Var x))) []], Instance [] (Tapp (Tcon (TconName "Show")) (Tcon (TconName s))) [ Fun "showsPrec" [Clause [Pwild,Pvar x] (Normal (App (Var ("show"++s)) (Var x))) []]], Instance [] (Tapp (Tcon (TconName "Eq")) (Tcon (TconName s))) [ Fun "==" [Clause [Pcon s [Pvar x],Pcon s [Pvar y]] (Normal (App (App (Var "==") (Var x)) (Var y))) []]] ] AS stringType :: String -> Q [Dec] stringType s = [| newtype $s = $s String show$s :: $s -> ShowS show$s ($s x) = showString x instance Show $s where showsPrec _ x = show$s x instance Eq $s where ($s x) ($s y) = (x==y) |] Maybe with a more specific type like : stringType :: TypeName -> Q [Dec] where TypeName would enforce the first letter must be capital rule. NOTE: to work this would require show$s to crate a function name from show prepended to the type name... Why is this not possible with the current template-haskell, and would this be possible with the proposed extensions (if not, why not, as the above seems very easy to read?) Regards, Keead Schupke.

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