September 2001 - Glasgow-haskell-users

Re: Converting [Word8] to CString
by Marcin 'Qrczak' Kowalczyk 15 Sep '01

15 Sep '01

Fri, 14 Sep 2001 23:40:42 -0700, Ashley Yakeley <ashley(a)semantic.org> pisze: > I'm looking for a function that will convert a [Word8] byte-array > to a CString (i.e. a C byte array) for the purposes of FFI. You can use newArray which allocates the C byte array using malloc so it must be freed by free, and cast the resulting pointer from Ptr Word8 to CString using castPtr. When the array is temporary, it's better (and faster) to use withArray list_of_Word8 $ \word8Ptr -> let cstring = castPtr word8Ptr in ... > And it has to be the _same_ list of bytes that comes through on > the native side. I don't unserstand this. -- __("< Marcin Kowalczyk * qrczak(a)knm.org.pl http://qrczak.ids.net.pl/ \__/ ^^ SYGNATURA ZASTÊPCZA QRCZAK

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Converting [Word8] to CString
by Ashley Yakeley 15 Sep '01

15 Sep '01

I'm looking for a function that will convert a [Word8] byte-array to a CString (i.e. a C byte array) for the purposes of FFI. foreign import "JVMBridge" "JVMBridge_FindClass" rawFindClass :: JavaVM -> CString -> IO JVMObjectRef; makeCString :: [Word8] -> IO CString; It has to work correctly with _any_ list of bytes. And it has to be the _same_ list of bytes that comes through on the native side. Note that we are only dealing with bytes here, this has nothing whatever to "characters", "text", "charsets", "Unicode", "encodings" or any of that nonsense. If this really can't be done, is there another type I can use? In some cases, the external function may call back into Haskell. -- Ashley Yakeley, Seattle WA

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14 Sep '01

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RE: Confused by profiling
by Simon Marlow 14 Sep '01

14 Sep '01

> I am confused by the GHC profiling output. I have put some abstracts > below to illustrate my confusion. > > I compiled my code with: > HFLAGS="-Wall -package lang -prof -auto-all" hmake -ghc main > and then ran it with: > ./main -t +RTS -p < test5.hs > > Here is some of main.prof: > individual inherited > COST CENTRE MODULE entries %time %alloc > %time %alloc > > [...] > parse Parser 1 0.0 0.0 > 81.4 62.3 > p_module Parser 0 0.0 0.0 > 81.4 62.3 > <|> PC_base 69517 20.3 5.7 > 81.4 62.3 > [...] > p_aexp_list Parser 0 0.0 0.0 > 0.0 0.3 > con2tag_Token# Tokens 880 0.0 0.0 > 0.0 0.0 > pIfThing PC_base 896 0.0 0.0 > 0.0 0.0 > <$ PC 0 0.0 0.0 > 0.0 0.3 > <$> PC 0 0.0 0.0 > 0.0 0.3 > pSucceed PC_base 896 0.0 0.3 > 0.0 0.3 > <*> PC_base 896 0.0 0.0 > 0.0 0.0 > <*> PC_base 896 0.0 0.0 > 0.0 0.0 > p_aexp_tuple Parser 0 0.0 0.0 > 0.0 0.3 > [...] > > and here is the code for p_aexp_list: > > p_aexp_list :: Parser Token Aexp > p_aexp_list = (Aexp_list . get_rights) > <$ pIfThing ((==) (Special '[')) > <*> pSList False p_comma p_exp > <* pIfThing ((==) (Special ']')) > > Now basically my problem is how things under p_aexp_list can > be entered > 896 times if p_aexp_list is entered 0 times - am I reading it wrong? Hmmm. I suspect it may be to do with the fact that p_aexp_list isn't a function, it's a CAF (constant applicative form - basically a top-level expression). The "entries" field counts the number of times an SCC annotation is executed, which corresponds more to "calls" than entries. I must admit I haven't thought too hard about this. It might be helpful to see what happens to the code inside the compiler: p_aexp_list = {-# SCC "p_aexp_list" #-} ... this SCC annotation gets executed once, when p_aexp_list is first entered, and you'll probably find it elsewhere on the profile under one of the CAF entries. The first time it is entered, p_aexp_list reduces to a function closure with the SCC annotation attached to it, so subsequent enters don't actually execute the SCC they just append it to the current cost-centre-stack. Perhaps the act of appending an SCC annotation when entering a function closure should bump the entry counts for all the cost centres in the stack. That might yield more reasonable-looking figures. Cheers, Simon

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RE: problems exporting haskell functions
by Simon Marlow 14 Sep '01

14 Sep '01

Hi there, > Hello, I have tried to export haskell functions, but I > haven't been able to compile anything and obtain a executable > file. My program has two parts. > - Haskell part: > module Hex where > fh :: Int -> Int > foreign export "f" fh :: Int -> Int > fh x = 7 > > - C part: > #include <stdio.h> > #include <stdlib.h> > extern int f(int x); > > int main( ){ > int a; > a = f(5); > printf("%d\n",a); > return 0; > } When you provide your own main() function, you have to arrange to initialize GHC's runtime system. I've attached some example code, and I've added some material to the User's Guide for the next release which explain how to do this. Cheers, Simon

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Confused by profiling
by Ian Lynagh 14 Sep '01

14 Sep '01

Hi all I am confused by the GHC profiling output. I have put some abstracts below to illustrate my confusion. I compiled my code with: HFLAGS="-Wall -package lang -prof -auto-all" hmake -ghc main and then ran it with: ./main -t +RTS -p < test5.hs Here is some of main.prof: individual inherited COST CENTRE MODULE entries %time %alloc %time %alloc [...] parse Parser 1 0.0 0.0 81.4 62.3 p_module Parser 0 0.0 0.0 81.4 62.3 <|> PC_base 69517 20.3 5.7 81.4 62.3 [...] p_aexp_list Parser 0 0.0 0.0 0.0 0.3 con2tag_Token# Tokens 880 0.0 0.0 0.0 0.0 pIfThing PC_base 896 0.0 0.0 0.0 0.0 <$ PC 0 0.0 0.0 0.0 0.3 <$> PC 0 0.0 0.0 0.0 0.3 pSucceed PC_base 896 0.0 0.3 0.0 0.3 <*> PC_base 896 0.0 0.0 0.0 0.0 <*> PC_base 896 0.0 0.0 0.0 0.0 p_aexp_tuple Parser 0 0.0 0.0 0.0 0.3 [...] and here is the code for p_aexp_list: p_aexp_list :: Parser Token Aexp p_aexp_list = (Aexp_list . get_rights) <$ pIfThing ((==) (Special '[')) <*> pSList False p_comma p_exp <* pIfThing ((==) (Special ']')) Now basically my problem is how things under p_aexp_list can be entered 896 times if p_aexp_list is entered 0 times - am I reading it wrong? And the only place p_aexp_list is called from is p_aexp_init = p_aexp_qvar <|> p_aexp_gcon <|> p_aexp_literal <|> p_aexp_paren <|> p_aexp_tuple <|> p_aexp_list <|> p_aexp_arith <|> p_aexp_listcomp <|> p_aexp_left <|> p_aexp_right but my reading of the profile output shows it as being called from <|> which is in turn called from p_module (all lines in the second [...] are indented with at least " "). Am I missing something obvious? Thanks Ian

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RE: ghc/HopenGL/cygwin/W2K
by Simon Peyton-Jones 14 Sep '01

14 Sep '01

Clifford In the next few days we'll release GHC 5.02. The Windows version of that will not require any version of cygwin; it comes complete, and you don't need to install anything else to make it work. (Nor does it mind if you have some version of cygwin installed, a surprisingly difficult criterion to satisfy, given Window's DLL story.) So I suggest you wait a few days. I do mean days and not weeks! (There is a slightly experimental Windows binary download you can try meanwhile; I enclose the message announcing it.) I'm not certain whether HOpen/GL has 'caught up' to GHC 5.02, but I'm sure it will shortly, and any differences will be of the trivial kind. Simon | -----Original Message----- | From: Clifford Beshers [mailto:beshers@cs.columbia.edu] | Sent: 14 September 2001 04:14 | To: glasgow-haskell-users(a)haskell.org | Subject: ghc/HopenGL/cygwin/W2K | | | | | I'm trying to get to the point where I can use ghc and OpenGL | under Windows 2000. Unfortunately, I'm lost in a maze of | version numbers. | | I had cygwin-1.3.2 installed, I think, which did not match | the 1.3.1 used in the ghc-4.08 package. I tried to install | cygwin 1.3.1, but got 1.3.3 instead. Nowhere can I find a | course for 1.3.1. Nor can I find 5.00.2 compiled for | Windows, though there is some mention of W2K support in the | documentation. | | Can anyone provide me with a recent road map? I don't mind | compiling everything, if that's what it takes, I just feel | I'm wandering in the wilderness. | | Thanks, | | Clifford Beshers | | | | _______________________________________________ | Glasgow-haskell-users mailing list | Glasgow-haskell-users(a)haskell.org | http://www.haskell.org/mailman/listinfo/glasgow-| haskell-users |

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ghc/HopenGL/cygwin/W2K
by Clifford Beshers 13 Sep '01

13 Sep '01

I'm trying to get to the point where I can use ghc and OpenGL under Windows 2000. Unfortunately, I'm lost in a maze of version numbers. I had cygwin-1.3.2 installed, I think, which did not match the 1.3.1 used in the ghc-4.08 package. I tried to install cygwin 1.3.1, but got 1.3.3 instead. Nowhere can I find a course for 1.3.1. Nor can I find 5.00.2 compiled for Windows, though there is some mention of W2K support in the documentation. Can anyone provide me with a recent road map? I don't mind compiling everything, if that's what it takes, I just feel I'm wandering in the wilderness. Thanks, Clifford Beshers

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shell to run functions
by Johansson Mikael 12 Sep '01

12 Sep '01

Hello! I have problems running functions in a haskell program being able to give input and get output via the keyboard. I have a glasgow compiler and have successfully made a compiled and runned a program wich read a char and writes it back to screen. main :: IO () main = do c <- getChar putChar c But when I try to write a program with this function: f x = x mod 7 == 0 || x mod 10 == 7 || x div 10 mod 10 == 7 The IO doesn't seem to work How do I put programs like this in a IO shell. Thanks in advance. Mikael Johansson Volvo Aero Corporation Military Engines Trollhättan Dept. 7164MJ SE-461 81 Trollhättan, Sweden phone +46 520 940 61 e-mail: mikael.mj.johansson(a)volvo.com

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Re: A question about Unicode support
by Marcin 'Qrczak' Kowalczyk 11 Sep '01

11 Sep '01

Tue, 11 Sep 2001 13:19:54 -0300 (GMT), Pablo Pedemonte <ppedemon(a)sol.info.unlp.edu.ar> pisze: > Ghc 5.00.2 provides (initial) Unicode support, so I thought the > chr function would do. But it seems it still rejects Int values > greater than 0xFF. It doesn't. -- __("< Marcin Kowalczyk * qrczak(a)knm.org.pl http://qrczak.ids.net.pl/ \__/ ^^ SYGNATURA ZASTÊPCZA QRCZAK

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