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read-substring unbound?
by linsmi＠coretech.co.nz 23 Fév '05

23 Fév '05

Hello all, I'm just getting into the Gambit environment - looks very nice. My first wee project for myself is to implement Chris Double's continuation based web server. The ability to serialize continuations makes Gambit an attractive platform. My question is regarding the read-substring procedure. The documentation lists this procedure, but at the Gambit REPL it is unbound: > read #<procedure #2 read> > read-subu8vector #<procedure #3 read-subu8vector> > read-substring *** ERROR IN (console)(a)4.1 -- Unbound variable: read-substring 1> Are the docs ahead of the implementation? Thanks Lindsay

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macro-expansion bug (?)
by dev null 22 Fév '05

22 Fév '05

Hi, The following works in chicken and bigloo, but fails on gambit 4.0b12: --------------------------------------------------------------------------------------- (define-macro (build-funcs) (define any '(list? number? string?)) (define funcnames `((is-string string?) (is-number number?) (is-list list?) (is-any ,any))) (define (build desc) (let ((name (car desc)) (tests (if (list? (cadr desc)) (cadr desc) (cdr desc)))) `(define ,name (lambda (o) (or ,@(map (lambda (x) (list x 'o)) tests)))))) `(begin ,@(map build funcnames))) (pp (lambda () (build-funcs) #t)) (build-funcs) (is-any "dd") --------------------------------------------------------------------------------------- It seems that the reference to the `any' variable is unbound inside `funcnames'. If you move the definition of `any' outside of the body of `build-funcs', everything works fine. Not sure if this is a bug, or a misunderstanding on my part. Best Regards, Ben

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RE: [gambit-list] Linking to C++ problems
by Dan Hristodorescu 22 Fév '05

22 Fév '05

Hi Marc, The problem I had in my test program was because I was compiling the DLL with -D___DYNAMIC. Without this flag the test program was fine. The real program I use still crashes and I have to figure out why. It works fine without the actual call to the scheme method; Gambit initialization doesn't cause any problems. I assume it's about some linking settings but I have to investigate more. I see your point about using the C++ compiler. I was using Gambit compiled by the default configure script which probably uses the C compiler and that's why I was mixing C with C++. Thanks for clearing that out for me. I'll recompile the runtime and try again. Thanks, Dan. -----Original Message----- From: Marc Feeley [mailto:feeley@IRO.UMontreal.CA] Sent: Monday, February 21, 2005 5:55 PM To: dhristodorescu(a)borderfree.com Cc: gambit-list(a)IRO.UMontreal.CA Subject: Re: [gambit-list] Linking to C++ problems > Sorry to replay to my own message but I figure out what was the = > problem. > It was just the mangling of DLL exported symbols (I was referring a = > wrong > name); it works fine now. Great. > The only relevant part of the message that remains is the one about the > extern "C" generation. I don't understand your point here. You should either compile the whole Gambit runtime system and your program with a C compiler, or with a C++ compiler, and then the names will be mangled appropriately. Are you mixing C and C++ code? (this is a bad idea in general because of the way exceptions are handled....) Marc

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RE: [gambit-list] Linking to C++ problems
by Dan Hristodorescu 22 Fév '05

22 Fév '05

Sorry to replay to my own message but I figure out what was the problem. It was just the mangling of DLL exported symbols (I was referring a wrong name); it works fine now. The only relevant part of the message that remains is the one about the extern "C" generation. Thanks, Dan. -----Original Message----- From: Dan Hristodorescu [mailto:dhristodorescu@borderfree.com] Sent: Monday, February 21, 2005 11:31 AM To: gambit-list(a)IRO.UMontreal.CA Subject: [gambit-list] Linking to C++ problems Hello, I am using Gambit4b12 to write a plugin for a C++ program. I've done some tests and had some success although right now I'm having some problems when using it in a DLL. First I would like to suggest a small improvement for the C code generation. Maybe I'm missing a switch to pass to gsc but every time I generate the C code I have to add extern "C" {} wrapper around each file after I move all the #include outside that block. I also noticed that gambit.c doesn't have a extern "C" wrapper and I had to add it. I think it would be simple to automatically add: #ifdef __cplusplus extern "C" {} #endif wrapper when generating the code. I don't know how easy would be to extract the includes in c-declare outside that wrapper but it would be nice to avoid manually editing the file. The problem I'm having right now is that the code which runs fine in a single standalone program crashes when is called in a loaded DLL. I think it must be something in the way the initialization has to be done but the documentation is not too clear. If someone would be able to give me a hint I would appreciate it. I am using mingw on Windows and I get this error: Program received signal SIGSEGV, Segmentation fault. 0x1012a67f in ___CHARSTRING_to_UCS2STRING () from c:\Gambitc_project\finalePlugin\testing\test.dll (gdb) bt #0 0x1012a67f in ___CHARSTRING_to_UCS2STRING () from c:\Gambitc_project\finalePlugin\testing\test.dll #1 0x00000000 in ?? () from #2 0x0022fe68 in ?? () #3 0x101248b1 in ___alloc_mem () from c:\Gambitc_project\finalePlugin\testing\test.dll Previous frame inner to this frame (corrupt stack?) The code is bellow. Thank you, Dan Hristodorescu. - Main program: #include <windows.h> #include <stdio.h> #include "note.h" typedef void (*EntryPointfuncPtr)(EXNOTE*); EntryPointfuncPtr callEntryPoint; HINSTANCE library; int main(int argc,char **argv) { library = LoadLibrary("test.dll"); // Check to see if the library was loaded successfully if (library == 0) { printf("Couldn't load the DLL"); exit(1); } EXNOTE* note1 = new EXNOTE(); note1->tcd=1; note1->alteration=1; note1->noteID=1; note1->flag=1; printf("Address=0x%X\n", note1); callEntryPoint = (EntryPointfuncPtr)GetProcAddress(library,"_Z10entryPointP6EXNOTE"); (*callEntryPoint)(note1); printf("Note->tcd= %d\n", note1->tcd); printf("Note->alteration= %d\n", note1->alteration); printf("Note->noteID= %d\n", note1->noteID); printf("Note->flag= %d\n", note1->flag); delete note1; } DLL code: #include <windows.h> #include <stdio.h> #include "note.h" extern "C" void pluginEntry(EXNOTE*); #define ___VERSION 40062 #include "gambit.h" #define SCHEME_LIBRARY_LINKER ____20_testscm__ ___BEGIN_C_LINKAGE extern ___mod_or_lnk SCHEME_LIBRARY_LINKER (___global_state_struct*); ___END_C_LINKAGE CALLBACK void entryPoint(EXNOTE* note1) { ___setup_params_struct setup_params; ___setup_params_reset (&setup_params); setup_params.version = ___VERSION; setup_params.linker = SCHEME_LIBRARY_LINKER; ___setup (&setup_params); pluginEntry(note1); ___cleanup (); } note.h file: #ifndef _NOTE_H_ #define _NOTE_H_ typedef short twobyte; typedef unsigned long ufourbyte; typedef ufourbyte FLAG_32; class EXNOTE { public: twobyte tcd; twobyte alteration; twobyte noteID; FLAG_32 flag; EXNOTE() : tcd(0), alteration(0), noteID(0), flag(0) {} ~EXNOTE() {} }; #endif Scheme code: (c-declare " #include \"note.h\" ") (c-define-type twobyte short) (c-define-type ufourbyte unsigned-long) (c-define-type FLAG_32 ufourbyte) ;; ;;;; EXNOTE ;;; (c-define-type EXNOTE* (pointer "EXNOTE")) (define EXNOTE-tcd (c-lambda (EXNOTE*) twobyte "___result = ___arg1->tcd;")) (define EXNOTE-tcd-set! (c-lambda (EXNOTE* twobyte) void "___arg1->tcd = ___arg2;")) (define transpose-note (lambda (note step) (EXNOTE-tcd-set! note (+ (EXNOTE-tcd note) step)))) (c-define (pluginEntry x) (EXNOTE*) void "pluginEntry" "extern" (write x) (newline) (transpose-note x 3))

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Linking to C++ problems
by Dan Hristodorescu 21 Fév '05

21 Fév '05

Hello, I am using Gambit4b12 to write a plugin for a C++ program. I've done some tests and had some success although right now I'm having some problems when using it in a DLL. First I would like to suggest a small improvement for the C code generation. Maybe I'm missing a switch to pass to gsc but every time I generate the C code I have to add extern "C" {} wrapper around each file after I move all the #include outside that block. I also noticed that gambit.c doesn't have a extern "C" wrapper and I had to add it. I think it would be simple to automatically add: #ifdef __cplusplus extern "C" {} #endif wrapper when generating the code. I don't know how easy would be to extract the includes in c-declare outside that wrapper but it would be nice to avoid manually editing the file. The problem I'm having right now is that the code which runs fine in a single standalone program crashes when is called in a loaded DLL. I think it must be something in the way the initialization has to be done but the documentation is not too clear. If someone would be able to give me a hint I would appreciate it. I am using mingw on Windows and I get this error: Program received signal SIGSEGV, Segmentation fault. 0x1012a67f in ___CHARSTRING_to_UCS2STRING () from c:\Gambitc_project\finalePlugin\testing\test.dll (gdb) bt #0 0x1012a67f in ___CHARSTRING_to_UCS2STRING () from c:\Gambitc_project\finalePlugin\testing\test.dll #1 0x00000000 in ?? () from #2 0x0022fe68 in ?? () #3 0x101248b1 in ___alloc_mem () from c:\Gambitc_project\finalePlugin\testing\test.dll Previous frame inner to this frame (corrupt stack?) The code is bellow. Thank you, Dan Hristodorescu. - Main program: #include <windows.h> #include <stdio.h> #include "note.h" typedef void (*EntryPointfuncPtr)(EXNOTE*); EntryPointfuncPtr callEntryPoint; HINSTANCE library; int main(int argc,char **argv) { library = LoadLibrary("test.dll"); // Check to see if the library was loaded successfully if (library == 0) { printf("Couldn't load the DLL"); exit(1); } EXNOTE* note1 = new EXNOTE(); note1->tcd=1; note1->alteration=1; note1->noteID=1; note1->flag=1; printf("Address=0x%X\n", note1); callEntryPoint = (EntryPointfuncPtr)GetProcAddress(library,"_Z10entryPointP6EXNOTE"); (*callEntryPoint)(note1); printf("Note->tcd= %d\n", note1->tcd); printf("Note->alteration= %d\n", note1->alteration); printf("Note->noteID= %d\n", note1->noteID); printf("Note->flag= %d\n", note1->flag); delete note1; } DLL code: #include <windows.h> #include <stdio.h> #include "note.h" extern "C" void pluginEntry(EXNOTE*); #define ___VERSION 40062 #include "gambit.h" #define SCHEME_LIBRARY_LINKER ____20_testscm__ ___BEGIN_C_LINKAGE extern ___mod_or_lnk SCHEME_LIBRARY_LINKER (___global_state_struct*); ___END_C_LINKAGE CALLBACK void entryPoint(EXNOTE* note1) { ___setup_params_struct setup_params; ___setup_params_reset (&setup_params); setup_params.version = ___VERSION; setup_params.linker = SCHEME_LIBRARY_LINKER; ___setup (&setup_params); pluginEntry(note1); ___cleanup (); } note.h file: #ifndef _NOTE_H_ #define _NOTE_H_ typedef short twobyte; typedef unsigned long ufourbyte; typedef ufourbyte FLAG_32; class EXNOTE { public: twobyte tcd; twobyte alteration; twobyte noteID; FLAG_32 flag; EXNOTE() : tcd(0), alteration(0), noteID(0), flag(0) {} ~EXNOTE() {} }; #endif Scheme code: (c-declare " #include \"note.h\" ") (c-define-type twobyte short) (c-define-type ufourbyte unsigned-long) (c-define-type FLAG_32 ufourbyte) ;; ;;;; EXNOTE ;;; (c-define-type EXNOTE* (pointer "EXNOTE")) (define EXNOTE-tcd (c-lambda (EXNOTE*) twobyte "___result = ___arg1->tcd;")) (define EXNOTE-tcd-set! (c-lambda (EXNOTE* twobyte) void "___arg1->tcd = ___arg2;")) (define transpose-note (lambda (note step) (EXNOTE-tcd-set! note (+ (EXNOTE-tcd note) step)))) (c-define (pluginEntry x) (EXNOTE*) void "pluginEntry" "extern" (write x) (newline) (transpose-note x 3))

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[gambit-list] Suggestion for configuring gambit on high-end x86 processors.
by Bradley Lucier 16 Fév '05

16 Fév '05

Marc: High-end P4, Athlon, etc., as well as Athlon 64, have 64-bit floating-point instructions pretty much the same as any other RISC (I don't mean the fused multiply-add of IBM's Power). This is accessed through the SSE2 instruction set on Intel, and similar things on AMD's Athlon. Some algorithms in _num.scm (for converting strings to and from floating-point numbers, for example) rely on proper 64-bit floating-point arithmetic. Gambit simulates this by setting the rounding precision to 64-bits on x86's 80-bit floating-point stack, but there is still the possibility of double rounding, especially for denormalized numbers, because of the extended exponent range of 80-bit numbers on the floating-point stack. I'm thinking it might be a good thing for Gambit's configure script to test for the availability of SSE2 or the similar thing for AMD and to set those options when building Gambit with gcc. Brad

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RE: [gambit-list] New types
by Logan, Patrick D 15 Fév '05

15 Fév '05

A functor is I think just a first-class function, either named or anonymous, e.g. a (lambda (...) ...) I think the usage here is more like "combinator", i.e. a functor with no free variables that can be combined with other combinators to create new kinds of compositions the way objects in an object-oriented program might be composed. (aka the "part-of" relationship rather than the "is-a" relationship.) I may be putting words in David's mouth that have nothing to do with his message. 8^/ -Patrick >-----Original Message----- >From: Eduardo Cavazos > >What's a functor? Can you show me an example of how they are better in some >way? > >On Mon, 14 Feb 2005 09:24:59 +0530, david rush <kumoyuki(a)gmail.com> wrote: >> > ;; In an object system like the one I made it's much shorter: >> >> Well, I used to think that way too. Believe me, you're on well-trodden >> ground here. >> >> Anyway I switched to heavy use of functors because I got tired...

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Error handler in 3.0
by Eduardo Cavazos 15 Fév '05

15 Fév '05

Is there an undocumented way to specify an error handler in Gambit 3.0? I mean, instead of going into a nested REPL, can Gambit run a function that we provide? I wrote an X11 window manager with Gambit 3.0. (It's very fast! ;-) ) I run it inside Gambit in interactive mode so that I can watch the log and interact with the system if there's an error. However, if I've switched to a desktop besides the one with the xterm/REPL, and the wm crashes, I can't see the window I need... So I basically need a simple error handler that will map that window. In the meantime I've taken to running the wm from a virtual console under linux (F1, F2, F3, etc...) and switching to it whenever it crashes. For times when it's really unstable, I just use Xnest. Eduardo

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Re: [gambit-list] New types
by Eduardo Cavazos 14 Fév '05

14 Fév '05

Thanks for the suggestion Marc. I think this will work perfectly. Here is the reason that I'd like to stick with the procedural representation instead of using Gambit structures directly. (define-structure point x y) (define-structure airplane pos vel) (define a (make-airplane (make-point 10 10) (make-point 0 0))) ;; Accessing the x coordinate of the airplane: (point-x (airplane-pos a)) ;; In an object system like the one I made it's much shorter: [[a pos:] x:] Getting at an object inside an object inside an object... in a struct/record system that typically accompanies Scheme implementations can be a pain in that it's so verbose. Even in C all you have to write is the name of the variable and the name of the field (plus the dot or arrow). "Different things should look different". By convention I use brackets whenever accessing or setting a field in an object. To set the value of x in the airplane above it would look like this: [[a pos:] x: 5] As opposed to this: (point-x-set! (airplane-pos a) 5) Structs in Xlib have pretty verbose names. It's nice to say this: [attr border_pixmap:] Instead of this: (XSetWindowAttributes-border_pixmap attr) I can think of more examples, but anyone that has programmed large Scheme projects surely knows this pain. In Gambit we have two styles of keywords. foo: and :foo. I use the post-colon keywords to denote fields. As another convention, I considered using pre-colon keywords to denote methods. Eduardo Cavazos On Tue, 8 Feb 2005 16:11:31 -0500, Marc Feeley <feeley(a)iro.umontreal.ca> wrote: > > Is there a way to create new primitive types in Gambit? I'm using 3.0 > > but I'm interested in answers regarding either version. > > In 3.0 and 4.0 you can use define-structure: > > Gambit Version 3.0 > > > (define-structure foo a b) > > (define x (make-foo 11 22)) > > x > #s(foo (a 11) (b 22)) > > (foo? x) > #t > > (foo? car) > #f > > (vector? x) > #f > > If you really want to keep your procedural representation, you can > access a procedure's "code" pointer to distinguish closures created > from one lambda from closures created from another lambda. Here's some > sample code: > > (define eq-procedure-code? ; this handles compiled and interpreted code > (lambda (proc1 proc2) > (if (##closure? proc1) > (and (##closure? proc2) > (if (##interp-procedure? proc1) > (and (##interp-procedure? proc2) > (eq? (##interp-procedure-code proc1) > (##interp-procedure-code proc2))) > (eq? (##closure-code proc1) > (##closure-code proc2)))) > (eq? proc1 proc2)))) > > (define make-adder > (lambda (x) > (lambda (y) > (+ x y)))) > > (define make-multiplier > (lambda (x) > (lambda (y) > (* x y)))) > > (define f (make-adder 1)) > (define g (make-adder 2)) > (define h (make-multiplier 3)) > > (pp (eq-procedure-code? f car)) ; => #f > (pp (eq-procedure-code? f g)) ; => #t > (pp (eq-procedure-code? g h)) ; => #f > > > Marc Feeley >

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Global environment
by Eduardo Cavazos 12 Fév '05

12 Fév '05

Is there a way to access the global environment in Gambit 3.0? Something like a function that returns a table mapping symbols to their current values?

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