- Glasgow-haskell-users

catchAllIO
by Steinitz, Dominic J 12 Oct '01

12 Oct '01

Can anyone help? catchAllIO seems to live in Exception but I can't find it in the documentation "4.12. Exception". Dominic. ------------------------------------------------------------------------------------------------- To receive our special fares directly by email, register at http://www.britishairways.com/registration

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Bug in ghc-502 with system "cmd > tmp"?
by Bernd Holzmüller 12 Oct '01

12 Oct '01

Hi all, I have the following problem on Windows NT using ghc 5.02 from a cygwin bash-shell. Calls to System.system of the form system $ "grep -E " ++ show str ++ " " ++ file ++ " > tmp" do not work because of the ">" (ditto with "<"). Execution yields: grep: >: No such file or directory Hugs works fine here. Any solution/workaround? Thanks, Bernd Holzmüller

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Help in calling Haskell from C
by Mark Conway Wirt 12 Oct '01

12 Oct '01

I've been using hdirect for C <-> Haskell calls, and I've hit a bit of a snag. I'm using ghc 5.00.2 and hdirect 0.17. I've been able to call Haskell from C easily enough, but I've been unable to go the other way. I've tried following the directions in the hdirect manual, and tried building the examples in the hdirect distribution. Everything works up until final linking, where I receive undefined references. The C code should initialize the Haskell run-time, as it include the startup code: extern void startupHaskell (int argc, char* argv[]); startupHaskell(argc,argv); I'm compiling via ghc with the following options: ghc -package hdirect -fglasgow-exts -static -no-hs-main and the idl is compiled as such: ihc -s -fhs-to-c --gen-headers -fuse-ints-everywhere --output-h=.... Does hdirect work with ghc 5.00.2? I'm not receiving any errors in the build process, so I think my problems are more related to a lack of documentation, as opposed to a bug. Does anyone have any information (beyond what is in the hdirect documentation) on calling ghc-compiled code from C? The undefined references I'm getting are: undefined reference to `__init_Main' undefined reference to `Main_main_closure' Thanks in advance. I've looked though the mailing list archive and haven't found anything. If this has been answered before I apologize. --Mark

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hGetContents bug?
by Andre W B Furtado 11 Oct '01

11 Oct '01

If I open a file using "openFile" from the IO module (x <- openFile "foo.txt" ReadMode) and convert it to a String via hGetContents (y <- hGetContents x) and finally try to print the file on the screen (putStrLn y) I'll get a strange result if the file contains the character 1A-hexadecimal (or 26-decimal): all characters beyond this point won't be printed on the screen. If I use openFileEx (from IOExts module) rather than openFile, some characters will be printed after the 1A/26, but not all of them. I know this special character is related to EOF or something like that in Windows platforms, but is this the expected behavior of function hGetContents? (please reply to both the list AND me) Thanks, -- Andre Furtado

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Re: IO concurrency
by Max A . K . 11 Oct '01

11 Oct '01

On Thu, Oct 11, 2001 at 01:28:39PM +0200, Volker Stolz wrote: > In local.glasgow-haskell-users, you wrote: >>> interact hIn = do >>> line <- hGetLine hIn >>> numIn <- handleToInt {-made from handleToFd & fdToInt-} >>> -- threadWaitRead numIn {-3-} > > Why should uncommenting -3- help when it happens *after* the > hGetLine? It doesn't. It helps if going before. My fault. I pasted to the msg somehow edited code, so the additional lines and comments was not checked. > Is your Tcl-app printing out "click" or "click\n", i.e. > with the additional linefeed? Command 'puts "click"' makes implicit line brake, so yes, "click\n" > Did you try disabling blocking entirely? I tried. No effect, as expected. Max.

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Problem linking a COM DLL
by Lehti, Patrick 11 Oct '01

11 Oct '01

I am still trying to build a Haskell COM component with GHC 5.02 and HDirect (from http://www.galconn.com/~sof/hdirect-0.18-src.tar.gz) I have a problem linking the DLL, I always get this error message: /usr/lib/mingw/libmingw32.a(gccmain.o)(.text+0x88):gccmain.c: multiple definition of `__main' /usr/lib/libm.a(ds00023.o)(.text+0x0): first defined here I am calling ghc with this command: >ghc --mk-dll -o QuiPeX.dll Main.o ParseAndRender.o ParseAndRenderProxy.o ParseAndRenderProxy_stub.o ComDllMain.o dll_stub.o ComDllMain_stub.o -optdll--def -optdllParseAndRender.def -fglasgow-exts -syslib com -package text By the way, the same error occurs when trying to build the comserv example! Can anybody help me with that? Patrick

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No type lib generated by hdirect
by Lehti, Patrick 10 Oct '01

10 Oct '01

I am trying to build a Haskell COM component with HDirect (from http://www.galconn.com/~sof/hdirect-0.18-src.tar.gz) and "ghc 5.02". I have problems generating the type library: it is simply not created. Even the comserv example is not working because of the same problem. Could that be a bug in that HDirect version? Patrick

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posix library for Windows?
by Dean Herington 10 Oct '01

10 Oct '01

Is the posix library (-package posix) supposed to be supported on Windows? If not (as I expect to have confirmed), what are the alternatives for process control on Windows? Dean

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Re: Ptr and ForeignPtr Questions
by Ashley Yakeley 10 Oct '01

10 Oct '01

At 2001-10-10 01:19, I wrote: > foreign import "foo" raw_foo :: Ptr () -> IO (Ptr ()); > > foo :: Ptr SomeLinkedList -> IO (ConstPtr Char); > foo = importFunction raw_foo; Actually I don't need to convert the pointers, do I? If I have (Storable SomeLinkedList), I can just declare foreign import "foo" foo :: Ptr SomeLinkedList -> IO (Ptr Char); and it should work. The only thing that's missing is a ConstPtr type... -- Ashley Yakeley, Seattle WA

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Re: Ptr and ForeignPtr Questions
by Ashley Yakeley 10 Oct '01

10 Oct '01

At 2001-09-23 23:54, I wrote: >As you point out, there are restrictions >on just what existing C functions you can bind to. If your function looks >like this: > > const char* foo (struct SomeLinkedList*); > >...you have no choice but to write 'impedance-matching' code for that >function. On second thought, I wonder if this is really true? It seems possible to declare a "raw" import and then use Haskell to adapt: foreign import "foo" raw_foo :: Ptr () -> IO (Ptr ()); foo :: Ptr SomeLinkedList -> IO (ConstPtr Char); foo = importFunction raw_foo; instance Storable SomeLinkedList where { ... }; Of course you'd need a suitable definition of importFunction: class ConvertValueToRaw t r | t -> r where { importValue :: r -> t; exportValue :: t -> r; }; class ConvertFunctionToRaw t r | t -> r where { importFunction :: r -> t; }; instance (ConvertValueToRaw tv rv) => ConvertFunctionToRaw (IO tv) (IO rv) where { importFunction rawF = do { rv <- rawF; return (importValue rv); }; }; instance (ConvertFunctionToRaw tb rb,ConvertValueToRaw ta ra) => ConvertFunctionToRaw (ta -> tb) (ra -> rb) where { importFunction rawF ta = importFunction (rawF (exportValue ta)); }; instance ConvertValueToRaw (Ptr a) (Ptr ()) where { importValue = castPtr; exportValue = castPtr; }; instance ConvertValueToRaw Word8 Word8 where { importValue = id; exportValue = id; }; etc. -- Ashley Yakeley, Seattle WA

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