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Re: [gambit-list] Re: loading modules multiple times
by Christian 11 Aoû '05

11 Aoû '05

At 14:41 Uhr +0100 11.08.2005, Adam Langley wrote: >On 8/11/05, Christian <christian(a)pflanze.mine.nu> wrote: >> I'm wondering why you need that patch. ><snip> > >Yes, I could catch the load exception but I don't want to copy and >paste that code into every module. Of course I could that module >loading form into its own module, but then how do I load that? Maybe put (load "my-load") into your main program, which has that definition. Your modules would just use the already-loaded definition. > > Some words about the logic behind the error (from how I see it): load >> on source code can simply reload the source, there's no >> implementation problem with that. It does two things, reparse the >> source (which may have changed), and re-run it's body (which means, >> perform bindings, thus overwriting bindings which may have changed >> since after the first load). > >Perfectly true and loading a source file multiple times is just fine. > >I recognise the inconsistency between loading source multiple times >and loading a binary multiple times (with this patch); the former >running the body multiple times. > >But modules generally pretty quickly reach the point where they stop >changing too often and end up compiled. Many of my .scm files will >start with something like > >(load "srfi-1") > >But, if I do that, then I can't ever create a higher level module >which imports either srfi-1 itself and a lower module, or imports two >lower modules which do. > >Questions about design purity are moot while something so simple doesn't work. I've started exactly like you, e.g. realised that gambit doesn't offer a loading infrastructure which tracks what has been loaded, and also realised that using the namespace infrastructure manually (by writing separate "C header file alike" files) would be tedious, and that just aliasing bindings using those header files would be risky since if one piece of code overwrites that foo routine from bar.scm then every other piece of code also using that bar.scm's foo routine would suffer from the change as well, and after realising that I could also easily dispense of "make"&makefiles for tracking when modules have to be rebuilt from sources, I ended up with chjmodule. >chjmodule is a nice bit of code, but is very slow and has far too many >bodges necessitated by Gambit's code. Well, then maybe it's time now to make it faster and resolve the bodgery? Marc: * how can one cheaply copy a binding from one namespace to another? I'm using (eval `(define ,fully-qualified-to ,fully-qualified-to)) now, and that's the slowest part of the whole thing. * how can one do the same with runtime macro definitions? (I'm using something like (eval `(define-macro (,fully-qualified-to . args) (append ',fully-qualified-to args))) currently.) I'm sure the remaining bodgery can be removed as well (path handling, calling external commands -> provide better support, wrapping a file with some code before compilation -> do it on the s-expr level maybe?, I don't know how to keep position information yet). I'll summarize all remaining things which I find awkward as soon as someone asks for it or when I'm going over reimplementing it. Christian.

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Re: [gambit-list] Re: loading modules multiple times
by Adam Langley 11 Aoû '05

11 Aoû '05

On 8/11/05, Christian <christian(a)pflanze.mine.nu> wrote: > I'm wondering why you need that patch. <snip> Yes, I could catch the load exception but I don't want to copy and paste that code into every module. Of course I could that module loading form into its own module, but then how do I load that? > Some words about the logic behind the error (from how I see it): load > on source code can simply reload the source, there's no > implementation problem with that. It does two things, reparse the > source (which may have changed), and re-run it's body (which means, > perform bindings, thus overwriting bindings which may have changed > since after the first load). Perfectly true and loading a source file multiple times is just fine. I recognise the inconsistency between loading source multiple times and loading a binary multiple times (with this patch); the former running the body multiple times. But modules generally pretty quickly reach the point where they stop changing too often and end up compiled. Many of my .scm files will start with something like (load "srfi-1") But, if I do that, then I can't ever create a higher level module which imports either srfi-1 itself and a lower module, or imports two lower modules which do. Questions about design purity are moot while something so simple doesn't work. chjmodule is a nice bit of code, but is very slow and has far too many bodges necessitated by Gambit's code. I can understand that people might want load to retain its original behaviour and have this called load-once or some such. If there's any support for this I'll redo the patch. AGL -- Adam Langley agl(a)imperialviolet.org http://www.imperialviolet.org (+44) (0)7906 332512 PGP: 9113 256A CC0F 71A6 4C84 5087 CDA5 52DF 2CB6 3D60

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Re: loading modules multiple times
by Christian 11 Aoû '05

11 Aoû '05

>(define MODULE_ALREADY_LOADED > ((c-lambda () int "___result=___FIX(___MODULE_ALREADY_LOADED)"))) This should be (define MODULE_ALREADY_LOADED ((c-lambda () scheme-object "___result=___FIX(___MODULE_ALREADY_LOADED)"))) (still untested) Christian.

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loading modules multiple times
by Adam Langley 11 Aoû '05

11 Aoû '05

Currently, trying to (load x) twice results in an error. This is a problem when A and B each load C and a fourth file tries to load A and B. It's also a problem when using (include x) to debug a file which loads another. So I would suggest the load should be a no-op in the case that the file has already been loaded. I would submit a patch, but doing the obvious to setup.c:___os_load_object_file doesn't seem to work. AGL -- Adam Langley agl(a)imperialviolet.org http://www.imperialviolet.org (+44) (0)7906 332512 PGP: 9113 256A CC0F 71A6 4C84 5087 CDA5 52DF 2CB6 3D60

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Deadlock problem
by Matthew Morgan 11 Aoû '05

11 Aoû '05

I can't figure out why this deadlocks on me (I'm using beta 14): (let ((x (open-vector))) (thread-start! (make-thread (lambda () (write 1 x)))) (thread-start! (make-thread (lambda () (write 2 x)))) (read x) (read x)) *** ERROR IN ##thread-deadlock-action! -- Deadlock detected Shouldn't this run to completion (possibly blocking at times to wait for the writes), and return either 2 or 1? - Matt -- http://www.matthewmorgan.net/blog

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Re: [gambit-list] handling of macros
by Bradley Lucier 10 Aoû '05

10 Aoû '05

On Aug 8, 2005, at 1:17 PM, Christian wrote: >> BTW, I've made some corrections to (that version of) your library >> and put that up with my latest version of chjmodule on http:// >> scheme.mine.nu/gambit/chjmodule/ >> > > To be more precise: these are the relevant changes out of the diff: > > > (define-type html > id: a121f3a9-a905-4db5-b2c2-6da0a7e47046 > read-only: > - unprintable: > + ;;unprintable: cj: why making debugging more difficult? > > -- > > (define (protect x) > (cond ((pair? x) > (for-each protect x)) > ((html? x) > - (d (html-pre-tag x)) > + ;;(d (html-pre-tag x)) > + ;;cj: escape attribute values!: > + ;; example: pre-tag: ("\n<p" (" onmousedown=" "fun") (" > align=" "center") ">") > + (let ((l (html-pre-tag x))) > + (d (car l)) > + (let lp ((l (cdr l))) > + (if (not (null? l)) > + (let ((a (car l))) > + (cond ((pair? a) > + (d (car a)) > + (d #\") > + (protect (cdr a)) > + (d #\")) > + (else (d a))) > + (lp (cdr l)))))) > (protect (html-body x)) I just looked at the html-lib.scm I sent you, and indeed it does the same thing: (for-each (lambda (attribute) (##write-substring " " 0 1 port) (let ((name (attribute-name attribute))) (##write-substring name 0 (string-length name) port)) (if (attribute-takes-value? attribute) (begin (##write-substring "=\"" 0 2 port) (protect (attribute-value attribute)) (##write-substring "\"" 0 1 port)))) (html-form-attributes x)) So I must have added the same capability after the version that Marc started with. Sorry for not noticing that before. I tried to study the differences between the files using both diff and ediff in emacs, and the result was a mess. Later I used the emacs "Indent region" command on both files before using ediff, and that helped. I forgot the dt tag in the version that Marc and you used, so please add (define-tag dt start-newline?: #t) to your library. I also changed a lot more tags to start a newline. Perhaps I should just do as Oleg does in http://okmij.org/ftp/Scheme/SXML.scm and have all block-level html plus <BR> start a newline. Brad

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FIFO's on MinGW and MacOSX Gambit-Cb14
by Francois Magnan 10 Aoû '05

10 Aoû '05

Hi, I am trying to use FIFO's instead of open-process to communicate with a separate process (since open-process doesn't work on MinGW for the moment). It seems that there is also some problems with FIFO's. On MacOSX 10.4 (Gambit-Cb14) I get: (let ((fifo-in (create-fifo "/tmp/myfifo"))) (define p (open-output-file "/tmp/myfifo")) (write '(12 3 4) p)) *** ERROR IN (stdin)(a)27.13 -- Device not configured (open-output-file "/tmp/myfifo") On MinGW (Gambit-Cb14) I get: *** ERROR IN (stdin)(a)13.13 -- Unknown Error (create-fifo "/tmp/myfifo") When I do it step by step in the gsi interpreter on MacOSX it works!!! What am I missing? > (create-fifo "/tmp/myfifo") > (define p (open-output-file "/tmp/myfifo") > (write '(12 3 4) p)) Thank you, Francois Magnan

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Strange echo in pseudo-terminals on MacOSX10.4 Gambit-Cb14
by Francois Magnan 09 Aoû '05

09 Aoû '05

Hi, Me again... I just separated my questions to different threads... There is strange echo I get by communicating with a pseudo terminal process on MacOSX 10.4 Gambit-Cb14. I open a dummy process that is a pseudo-terminal using the open- process command and when I send data to the port that data gets repeated in the pseudo-terminal output-port. See the example below for better clarity. Can I turn off that echo? I cannot test it on the WinXP platform since open-process is not implemented for (MinGW or Cygwin). Thank you, Francois Magnan --------------------- ; Pseudo-terminal program (define (command-loop) (let ((command (read-line))) (serve-command command) (command-loop))) (define (serve-command command) (pp (list "got command" command))) (command-loop) ; build the above to an executable file called "/tmp/pttest" using gsc and gcc. --------------------- (define (test-pseudo-terminal) (let ((port (open-process (list path: "/tmp/pttest" stderr-redirection: #t pseudo-terminal: #t )))) ;(force-output port) (pp port) (force-output) (thread-sleep! 1) (display "toto\n" port) (force-output port) (pp (read-line port)) (pp (read-line port)) (close-port port))) (test-pseudo-terminal) ; execute the above in a gsi interpreter ; On MacOSX 10.4 I get ; "\33[1mtoto\33[m" ;"(\"got command\" \"toto\")"

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file-exists? on
by Francois Magnan 09 Aoû '05

09 Aoû '05

Hi, On WindowsXP (MinGW) the promitive file-exists? seems to be broken in Gambit-Cb14... Is anybody experiencing the same problem? Thank you, Francois Magnan (file-exists? "/bin/ls") ; Works on MacOSX 10.4 (file-exists? "C:/Decads/bin/decads.exe") ; Fails on Windows XP (MinGW) although that file exists on my machine.

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(begin) mini-issue
by Christian 08 Aoû '05

08 Aoû '05

Hello I've noticed some time ago that (begin) is the best thing a macro can return if it doesn't want to insert any code. Like: (define-macro (STRIP . x) '(begin)) or (define-macro (toggle-foo-at-compile-time) (set! foo (not foo)) '(begin)) It's better than returning #f or #!void since (begin) even works when being put before internal definitions or declarations at the start of a function, like: (define (bar x) (toggle-foo-at-compile-time) (define a 5) ...) Encouraged by this, I hoped that it would also work in tail position, e.g. just disappear and not disturb delivery of the return value. Like: (define (baz x) (toggle-foo-at-compile-time) (+ baz 5) (toggle-foo-at-compile-time)) But this is giving a compilation error, "Ill-formed special form: begin". Simpler test cases: ; this is the only case which doesn't give a compile-/expansion time error: ; (but it won't display "one" in the repl, just as it would return #!void) (begin "one" (begin)) ;(display (begin "two" (begin))) ; ^- Ill-formed special form: begin ;(pp (lambda() (begin "three" (begin)))) ; ^- Ill-formed special form: begin ; this works, of course, printing "FOUR". (pp (begin "three" (begin "FOUR"))) The same happens in the interpreter and the compiler. (This is on gambc40b14 on Debian x86.) This construct could be useful in some (rare) cases (see my following mail on macro-debugging). R5RS doesn't seem to say anything on this. Scheme48 and Mzscheme act the same in all cases. Gauche and SCM don't complain but just always return #<undef> / #<unspecified> from such a construct. bigloo -i only complains in the lambda creation case, otherwise it returns #unspecified. Thanks, Christian.

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