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Re: [gambit-list] Passing lambdas as callbacks to C functions
by schemeway＠sympatico.ca 05 Fév '07

05 Fév '07

Phil, > I ran into problems using lambda expressions as callbacks when wrapping > libcsv and I've boiled it down to this testcase. Can anybody tell me why > this crashes?: >... > looper is a c function which takes a scheme lambda and repeated invokes > it using the 'call_lambda' bridging function. > > When I gsc compile it and run '(main)' after a bunch of looping and > printing it crashes with: > ERROR IN looper -- Operator is not a PROCEDURE > ('#<return #2>) > > Any ideas? (or am I being stupid?!) I'm just guessing here, but could it be that, since your lambda expression is not reference anywhere else in your Scheme code, it gets GC'd? Dominique

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Gambit-compatible libraries
by Levi Pearson 04 Fév '07

04 Fév '07

Looking through the archives, I found a couple of references to efforts various people made to port SRFIs and other libraries to Gambit. I found Guillaume Germain's initial release of SRFIs, but there never seemed to be any followup releases. SLIB apparently worked with Gambit 3.0, but does anyone know if it works with recent versions? Also, what is the Scheme Now! project and how will it be related to Gambit? I waited with much anticipation throughout December, but alas, I was disappointed. --Levi

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large files
by mb 04 Fév '07

04 Fév '07

hi, i coded a simple and stupid directory walker; however it stopped when scanning a file with a size > 4GB. After fiddling around a little i noticed that stat() fails an my system with files > 2GB unless one explicitly asks to use 64bit file offsets. So i had to add this define #define __USE_FILE_OFFSET64 to the os.h header and recompile gambit. This enforces that a call to stat is a call to stat64 under the hood. Also, this has some implications to the size of the struct 'stat' and various other os dependent file operations. I'm wondering if a check against the usage of 64bit file offsets etc should be added to the ./configure system? Did i something wrong while configuring gambit, or this issue already known? greets -alex

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Passing lambdas as callbacks to C functions
by Phil Dawes 03 Fév '07

03 Fév '07

Hi Marc, Hi Gambit List, I ran into problems using lambda expressions as callbacks when wrapping libcsv and I've boiled it down to this testcase. Can anybody tell me why this crashes?: ------- (c-define (call-lambda l) (scheme-object) void "call_lambda" "" (l)) (define looper (c-lambda (scheme-object) void #<<c-lambda-end while(1){ call_lambda(___ARG1); } c-lambda-end )) (define (main) (looper (lambda () (write "foo")))) -------- looper is a c function which takes a scheme lambda and repeated invokes it using the 'call_lambda' bridging function. When I gsc compile it and run '(main)' after a bunch of looping and printing it crashes with: ERROR IN looper -- Operator is not a PROCEDURE ('#<return #2>) Any ideas? (or am I being stupid?!) Many thanks, Phil

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Using Gambit Scheme on UNIX, question
by urrozalf＠vcn.bc.ca 03 Fév '07

03 Fév '07

Hello there, this is my first message. I am trying to run Gambit on my UNIX box, is an old machine just 250 MHz. I am running Solaris 9, I downloaded the "*.tar.gz" file, expanded it. Then using terminal I issued the command "tar xvf ****.tar", it worked fine. I have the Gambit directory on "/export/home/alfonso/MySoftware/Gambit***" Then I issued the command /.configure it worked fine, I think, now I don't know what is the next step, so I can start using Gambit. Any help will be appreciated. Thanks. Alfonso

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Transcript
by TJ 29 Jan '07

29 Jan '07

I'm trying to write my own transcripting functions, but it's not working -.- What I want is to have a custom repl "front-end" function that reads from stdin and passes it to the real REPL and also prints it to the stdout and to my transcript file. Also, the output from the real REPL will be printed on both the stdout and transcript files. Here's a diagram to help illustrate what I'm thinking of (ascii art): ------- -------- ----------------- | Stdin | | Stdout | | transcript-port | ------- -------- ----------------- | /|\ /|\ | | | \|/ \ / (proc input-splitter) \______________________/ | | | | | (proc output-splitter) | /|\ |_____________________________ | | | | \|/ \|/ | ----------------- ---------------------- | repl-input-port | | output-splitter-port | ----------------- ---------------------- \ /|\ \ | \ / | / \|/ / (proc ##repl) The problem is that (when compiled as a single program, which is what I want) the output seems to be buffered, even though I call force-output, and even if I open the port with buffering disabled. When run from the REPL however, nothing whatsoever gets sent to the transcript file, however the fake repl displays to stdout just fine. Here's a sample program: ;;========================================== Start (define transcript-port (open-output-file (list path: "transcript-test-output" create: 'maybe buffering: #f append: #f))) (define (my-repl) (define stdout (current-output-port)) ; just take the current input and (define stdin (current-input-port)) ; output ports. (define repl-input-port (open-string)) (define output-splitter-port (open-string)) (define (input-splitter) ; Sends stdin to the repl and the output splitter. (define (loop s) (display "input-split") (display s repl-input-port) (force-output repl-input-port) (display s output-splitter-port) (force-output output-splitter-port) (loop (read-line stdin))) (loop (read-line stdin))) (define (output-splitter) ; Sends output to the transcript and stdout. (define (loop s) (display "output-split") (display s transcript-port) (force-output transcript-port) (display s stdout) (force-output stdout) (loop (read-line output-splitter-port))) (loop (read-line output-splitter-port))) ; Start splitter procs. (thread-start! (make-thread input-splitter 'programmer-interface-input-splitter)) (thread-start! (make-thread output-splitter 'programmer-interface-output-splitter)) ; Start real repl. (set! ##stdio/console-repl-channel (##make-repl-channel-ports repl-input-port output-splitter-port)) (##repl) (close-port repl-input-port) (close-port output-splitter-port)) (my-repl) ;;=========================================== End Any idea what's wrong? TJ

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finally blocks
by Phil Dawes 29 Jan '07

29 Jan '07

Hi Gambit List, I'd like to have some functionality in gambit similar to 'finally' blocks in java/python where a block of code is always executed regardless of any exceptions thrown. I'm currently using an exception handler that catches the exception and re-raises it after doing the cleanup stuff, but this loses the original 'where the exception was raised from' metadata. Is there a better way? (or a better idiom for resource cleanup that I should be using?) Thanks, Phil

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finally blocks
by Phil Dawes 28 Jan '07

28 Jan '07

Hi Gambit List, I'd like to have some functionality in gambit similar to 'finally' blocks in java/python where a block of code is always executed regardless of any exceptions thrown. I'm currently using an exception handler that catches the exception and re-raises it after doing the cleanup stuff, but this loses the original 'where the exception was raised from' metadata. Is there a better way? (or a better idiom for resource cleanup that I should be using?) Thanks, Phil

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gambit on zaurus
by mb 22 Jan '07

22 Jan '07

hi, i found 2 messages in the archives regarding gambit on zaurus. Since i have the same problems getting it running, and no solution was posted to the list, i wonder if there is a solution at all to the problem mentioned in: https://webmail.iro.umontreal.ca/pipermail/gambit-list/2006-September/00083… The question that stays open is: >> What does this print? >> gsi/gsi -e "(pp (##subprocedure-parent-info (caar ##decomp- >> dispatch-table)))" it prints: #(#(#(0 #f) #(1 #f 98304 65538) #(2 #f 98304 65538)) #(rte $code)) -mb

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Nintendo DS Gambit Port
by Charles Scheme 16 Jan '07

16 Jan '07

Hello, I found out about the DS Gambit port after a Google search lead me to the gambit-list. I downloaded the file, but I'm sure how to get it working. I have a R4 Slot-1 card, which works with other homebrew software. Any ideas? Thanks. Charles

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