September 2001 - Glasgow-haskell-users

A question about Unicode support
by Pablo Pedemonte 11 Sep '01

11 Sep '01

Hi all! The question is really simple: how can I convert an Int into a Char? 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. So, what function shoud I use? Thanks in advance. Regards, Pablo

1 0

Re: GHC FFI Return Type Bug
by Marcin 'Qrczak' Kowalczyk 10 Sep '01

10 Sep '01

10 Sep 2001 13:20:33 -0600, Alastair David Reid <reid(a)cs.utah.edu> pisze: > So GHC's Int/Word implementation is different from Hugs'? Hugs > represents Word8 (say) by a 32 bit int but doesn't guarantee that the > top 24 bits are all zero. GHC does similarly, except that it does guarantee that unused bits are zero. Or one - in negative numbers. In other words it represents value x of type Int8 as if converted to Int. -- __("< Marcin Kowalczyk * qrczak(a)knm.org.pl http://qrczak.ids.net.pl/ \__/ ^^ SYGNATURA ZASTÊPCZA QRCZAK

1 0

RE: GHC FFI Return Type Bug
by Julian Seward (Intl Vendor) 10 Sep '01

10 Sep '01

Thanks. I think the decision here is to do the safe thing and mask the return results ourselves, since it's only one extra insn. This won't make it into 5.02, tho. J | -----Original Message----- | From: Sigbjorn Finne [mailto:sof@galconn.com] | Sent: Saturday, September 08, 2001 4:27 PM | To: Julian Seward (Intl Vendor) | Cc: partain(a)dcs.gla.ac.uk; Ashley Yakeley; GHC List | Subject: Re: GHC FFI Return Type Bug | | | Here's another data point on this topic - I asked around | inside of MS, and the consensus is that the contents of the | unused portions of EAX is undefined upon return (upper 3 | bytes for byte-sized return values, upper 2 for 16-bit | values). This is invariant of x86 calling convention on Win32 | (cdecl,stdcall,fastcall). Still no known doc/spec which | spells this out. | | ==> GHC's NCG and C backends need to know the sizes of the | unboxed Ints and Words involved in CCalls to generate correct code. | | --sigbjorn | | ----- Original Message ----- | From: "Sigbjorn Finne" <sof(a)galconn.com> | To: "Julian Seward (Intl Vendor)" <v-julsew(a)microsoft.com> | Cc: <partain(a)dcs.gla.ac.uk>; "Ashley Yakeley" | <ashley(a)semantic.org>; "GHC List" <glasgow-haskell-users(a)haskell.org> | Sent: Tuesday, August 07, 2001 16:00 | Subject: Re: GHC FFI Return Type Bug | | | > | > "Julian Seward (Intl Vendor)" <v-julsew(a)microsoft.com> writes: | > > | > > | > char fooble ( ... ) | > > | > { | > > | > return 'z'; | > > | > } | > > | > | > > | > on an x86, 'z' will be returned at the lowest 8 bits in %eax. | > > | > What I | > > | > > | > don't know is, is the C compiler obliged to clear the | upper 24 | > > | > bits | > > of | > > | > %eax, or does that onus fall on the callee? | > > | | > > | Yes, the callee is required to narrow <expr> in 'return | <expr>;' | > > | to fit that of the specified return type -- see 9.8 of Harbison | > > | and Steele. | > > | | > ... | > > So we don't need to worry about doing the masking on the Haskell | > > side, right? | > > | > | > Yes, that's been my understanding. But, as Carl Witty | rightly points | > out, a distinction can be made between narrowing down the | result value | > and the transmission of the narrowed result back to the caller. | > | > Carl's example doesn't fully convince me though, since the masking | > done in the code for "g" is patently redundant ("f" does | mask out the | > upper 3 bytes of %eax upon return). However, the example | given in the | > original bug report can be made to emit code that doesn't | mask %eax | > (via "gcc-2.96 -O" on an i686-pc-linux). Another data point is that | > MSVC also emits code that masks. | > | > So, indications are that you actually do need to mask on an | x86, but | > I've got no supporting documentation. If anyone is able to | dig up more | > info and/or know someone that could answer this one decisively, I'd | > interested to hear of their findings. | > | > --sigbjorn | > | > btw, the document specifying the x86 ABI, located via | > | > http://uwsg.iu.edu/hypermail/linux/kernel/0011.1/0596.html | > | > , doesn't cover this as far as I've been able to tell. | > | > | > | > _______________________________________________ | > Glasgow-haskell-users mailing list Glasgow-haskell-users(a)haskell.org | > http://www.haskell.org/mailman/listinfo/glasgow-haskell-users | |

3 2

RE: GHC FFI Return Type Bug
by Julian Seward (Intl Vendor) 10 Sep '01

10 Sep '01

| Speaking of 5.02 . Could someone enlighten us that are not on | the CVS mailing list about the state of things? When can we | expect the release? If I'm feeling optimistic, late this week; otherwise, sometime next week. We've had some stability problems, but I hope these are now solved. Another part of the delay stems from the fact that we're trying to get our new glorious automated test system to run with zero failures on all supported platforms. The upside of all this is that 5.02, when it eventually appears, should be pretty darn stable. (Famous last words ...) J

1 0

RE: GHC FFI Return Type Bug
by Julian Seward (Intl Vendor) 08 Sep '01

08 Sep '01

Sigbjorn Am confused by your answer. | > char fooble ( ... ) | > { | > return 'z'; | > } | > | > on an x86, 'z' will be returned at the lowest 8 bits in %eax. What I | > don't know is, is the C compiler obliged to clear the upper 24 bits of | > %eax, or does that onus fall on the callee? | | Yes, the callee is required to narrow <expr> in 'return | <expr>;' to fit that of the specified return type -- see 9.8 | of Harbison and Steele. So, a C compiler that cause f() to | return 0x7fffffff for the following, | | unsigned char g() | { | return 0x7fffffff; | } | | unsigned int f() | { | return g(); | } | | is in the wrong. [Notice that narrowing for signed integral | types is undefined in ISO C, but most current-day compilers | implement such narrowing ops the same way, i.e., by masking | off excess bits.] So we don't need to worry about doing the masking on the Haskell side, right? | > Also, I don't even know where to look for the specification | of details | > of the C calling conventions. Anyone got a clue? | > | | Harbison & Steele Chapters 6 and 9 cover the conversion rules | that apply to functions (and other expressions). As you no | doubt already know, lower-level details are the domain of a | platform's ABI. | | Sounds to me like unboxed sized Words and Ints is the | (unavoidable) way to go. Why would we need these unless we *did* need to worry about masking on the Haskell side? Pls clarify. J

2 2

RE: ghc packages for interactive use
by Simon Marlow 07 Sep '01

07 Sep '01

> How can I configure a ghc package for use with ghci? > what file does the linker try to load, and what is expected > as contents? For a Haskell library, the linker will attempt to load <lib>.o, where the batch compiler would normally look for lib<lib>.a (on Unix). You can construct <lib>.o from its constituent .o files using 'ld -r': ld -r -o <lib>.o Foo.o Bar.o or you can construct it from the .a library, like so: ld -r -o <lib>.o --whole-archive lib<lib>.a > is it libHSmypackage.so? do I have to set LD_LIBRARY_PATH manually? For normal C code, you can either build a shared library or a combined .o file as above. You don't need to use LD_LIBRARY_PATH - just tell GHCi where the library lives using the package spec. Cheers, Simon

1 0

[newbie]system programming ?
by hooh pxw 06 Sep '01

06 Sep '01

hi, ghc can be "alternative" C ? Say that, linux device driver developing, or low-level/independent GUI programming. FOLK(Functionally Overloaded Linux Kernel), vault, svgalib, GGI, seal, directFB,.. these project written in c, Is it can be replaced by GHC(*.lhs)? http://www.sealsystem.org http://gemini.sourceforge.net This 2 project is small. __________________________________________________ Do You Yahoo!? Get email alerts & NEW webcam video instant messaging with Yahoo! Messenger http://im.yahoo.com

4 3

Help to write program in haskell
by Mustafa Khalifa Aswad 05 Sep '01

05 Sep '01

I have function produce the string of char from list of list string i need how many time the elem occurece in the list the function as follow pins1 :: (Eq a) => [[a]] -> [a] pins1 [] = [] pins1 (xs:xss) = [x | x <- xs , or [ x `elem` ys | ys <- xss] ] the input is as follow : "[[\"u\",\"g\",\"c\",\"\",\"au\",\"aug\",\"augc\",\"augca\",\"ug\",\"ugc\",\"ugca\",\"gc\",\"gca\",\"ca\"],[\"a\",\"u\",\"g\",\"c\",\"\",\"au\", \"aug\",\"augc\",\"ug\",\"ugc\",\"gc\"],[\"a\",\"c\",\"\",\"ag\",\"agg\",\"aggc\",\"gg\",\"ggc\",\"gc\"]]" the output is as follow "[\"u\",\"g\",\"c\",\"\",\"au\",\"aug\",\"augc\",\"ug\",\"ugc\",\"gc\"]" the require function to produce output as follow "[(\"u\",2),(\"g\",2),(\"c\",3), ,(\"au\",2),(\"aug\",2),(\"augc\",1),(\"ug\",2),(\"ugc\",2),(\"gc\",2)]" please contact me on ( ceemka(a)cee.hw.ac.uk)

1 0

ghc packages for interactive use
by Johannes Waldmann 04 Sep '01

04 Sep '01

How can I configure a ghc package for use with ghci? what file does the linker try to load, and what is expected as contents? is it libHSmypackage.so? do I have to set LD_LIBRARY_PATH manually? I'm getting relocation errors when I just collect all the object files (which works for libHSmypackage.a): ... Loading package data ... linking ... done. Loading package frantk ... ghc-5.00.2: can't find .o or .so/.DLL for: HSfrantk (ld.so.1: /u/joe/built/lib/ghc-5.00.2/ghc-5.00.2: fatal: relocation error: file /home/joe/built/lib/frantk/libHSfrantk.so: symbol PrelBase_const_closure: referenced symbol not found) Best regards, -- -- Johannes Waldmann ---- http://www.informatik.uni-leipzig.de/~joe/ -- -- joe(a)informatik.uni-leipzig.de -- phone/fax (+49) 341 9732 204/252 --

1 0

problems exporting haskell functions
by Juan Ignacio Garcia Garcia 03 Sep '01

03 Sep '01

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; } I have tried to compile it using the glasgow-extensions, but it has links problems. Does anyone know if there is something wrong in my program? Does anyone know where I can find a little example program where haskell functions are exported? Thanks, J.I. García

1 0