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Can't load a given object file more than once
by Eduardo Cavazos 22 Mar '09

22 Mar '09

Hello, This is not actually that big a deal. But, let's say I compile a file: > (compile-file "/tmp/test-gambit-compiler/test-a.scm") #t Then load the resulting object file: > (load "/tmp/test-gambit-compiler/test-a") "/tmp/test-gambit-compiler/test-a.o1" OK, I wanna recompile it, but not have a bunch of old versions laying around. So delete the o1 file: > (delete-file "/tmp/test-gambit-compiler/test-a.o1") And recompile: > (compile-file "/tmp/test-gambit-compiler/test-a.scm") #t An error occurs if you try to load the new object file: > (load "/tmp/test-gambit-compiler/test-a") *** ERROR IN (console)(a)5.1 -- Can't load a given object file more than once (load "/tmp/test-gambit-compiler/test-a") 1> Sure, I understand that Gambit is preventing a reload of the exact same object file. But it must be doing a very simple accounting based on the name of the object file. Perhaps you can employ that newfangled high-performance file digest code that was recently shared. ;-) Anywho, no big deal. But it's a surprise. Ed

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smart-load
by Eduardo Cavazos 22 Mar '09

22 Mar '09

Hello, Here's fun hack that's a replacement for 'load'. I use something like this with Chicken. If the scheme file doesn't have a corresponding object file or if the object file is out of date, the scheme file is compiled and loaded. Otherwise the object file is loaded. (define (smart-load scheme-file) (let ((object-file (current-object-file scheme-file))) (cond ((and object-file (file-newer? object-file scheme-file) (not (member object-file *gambit-loaded-files*))) (set! *gambit-loaded-files* (cons object-file *gambit-loaded-files*)) (gambit-scheme-load object-file)) ((and object-file (file-newer? object-file scheme-file)) 'already-loaded) (else (print "Compiling file: " scheme-file "\n") (compile-file scheme-file) (smart-load scheme-file))))) Where the supporting procedures are: (define (file-newer? a b) (> (time->seconds (file-info-last-modification-time (file-info a))) (time->seconds (file-info-last-modification-time (file-info b))))) (define (current-object-file scheme-file) (let ((object-file? (let ((object-file-prefix (string-append (path-strip-directory (path-strip-extension scheme-file)) ".o"))) (lambda (file) (string-prefix? object-file-prefix file))))) (let ((object-files (sort-list (filter object-file? (directory-files (path-directory scheme-file))) string>))) (if (null? object-files) #f (string-append (path-directory scheme-file) (first object-files)))))) Ed

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glut callbacks
by Eduardo Cavazos 22 Mar '09

22 Mar '09

Hello, I was trying out the opengl library from the wiki. Some of the functions in the glut library are used to specify callbacks. For example, glutReshapeFunc. In the glut libraries of Ypsilon, Larceny, and Chicken, I'm able to pass a Scheme procedure to the 'glutReshapeFunc' procedure. Is this doable with Gambit? From the sound of the manual, it seems like this is not yet supported. Ed

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Web applications in Gambit
by Andrew Whaley 20 Mar '09

20 Mar '09

Hi Marc, Thanks for your email in response to my post on comp.lang.scheme. For the benefit of the other subscribers, I'm trying to create a web application framework using Gambit that is secure, performant and above all allows great developer productivity. I'm aiming for something similar to SISCWeb but a lot faster and able to support very many concurrent users. I already use Gambit for other things like my win-control library that I use for automated application testing so I really like Gambit. I've made some good progress in the last couple of days by finding the ssax-sxml library and Francisco Ferreira's basic scgi interface. Putting these together with a multithreaded dispatcher, I now have gambit serving complex SXML web pages in around 50ms which is about 20 times faster than SISCWeb with the same page. I have an immediate problem in that the main thread which listens for incoming connections and then spawns handler threads for each page requests works fine if I run it in the REPL window but that then prevents REPL from doing anything else. If I try and spawn a separate thread for this listener so that I can carry on using REPL then the listener stops running unless I repeatedly press return in the REPL window ! I want to keep REPL running concurrently with the listener so that I can redefine procedures on the fly during development rather than having to stop and start gsi and therefore losing any application state. Have I missed something here as it seems that threads are blocked whilst REPL is waiting for input ? I'm using 4.4.0 MinGW Windows version. I have enough working now to start on the continuations based web framework but pretty soon I'll need to try and interface with a backend database e.g. Oracle or MySQL. The obvious way to do this will be to use the relevant C API for the database but I'm guessing that if I call into C then all the pseudo-threads in Gambit will stop until the C call returns - is this correct ? This would probably OK for a short call but would be disastrous for a long running call e.g. to a database that has a latency of at least 30ms and could be several seconds for some queries. Do you have any thoughts on how I could do this ? Many thanks Andrew

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Garrett: ext4, application expectations and power management [LWN.net]
by Bradley Lucier 19 Mar '09

19 Mar '09

Marc: There is currently an active discussion about filesystem semantics in Linux; it appears that sometimes, maybe, perhaps, just possibly, applications should call fsync somewhere: http://lwn.net/Articles/323464/ And see other stories in Linux Weekly News. I just searched the lib directory of gambit, and I didn't find any active fsync's (there were two in IF 0'd code). Does that mean that I'm going to lose data when I use the file system as a poor man's database with gambit? (Actually, it's not so poor, it's quite nice to be able to read "database" information in S-expression format.) Just a heads up. Brad

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case INsensitivity with -:s
by Marijn Schouten (hkBst) 18 Mar '09

18 Mar '09

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Hi, is it possible to load syntax-case but not lose case sensitivity? $ gsi -e "(pp (eq? 'a 'A))" #f $ gsi -:s -e "(pp (eq? 'a 'A))" #t Marijn - -- Gods do not want you to think, lest they lose existence. Religions do not want you to think, lest they lose power. Marijn Schouten (hkBst), Gentoo Lisp project, Gentoo ML <http://www.gentoo.org/proj/en/lisp/>, #gentoo-{lisp,ml} on FreeNode -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.10 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iEYEARECAAYFAknBChwACgkQp/VmCx0OL2y+vgCdFd+kIS14PVRzxwunKYMop7X4 pkEAn1/YIec3Am+RbsDDhjCJFRgLJNeM =hnOF -----END PGP SIGNATURE-----

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polygon tessellation library?
by James Long 17 Mar '09

17 Mar '09

Does anyone have a Gambit Scheme library for tessellating 2d polygons with triangles? It should take a random number of 2d points and return a list of triangles. It doesn't need to handle holes. I've found one or two viable C++ libraries, but this requires me to write an FFI and possibly port it to C (I kind of want to avoid mixing C and C++). In an effort to avoid duplicating work, I thought I'd ask here first. - James

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Re: [gambit-list] streams srfi41
by Arthur Smyles 17 Mar '09

17 Mar '09

From: Pavel Dudrenov <dudrenov(a)gmail.com> To: Gambit List <Gambit-list(a)iro.umontreal.ca> Sent: Monday, March 16, 2009 8:01:44 PM Subject: [gambit-list] streams srfi41 Check out http://smyles.com/projects/r6gambit It doesn't implement rnrs records fully yet. I do have an implementation of srfi 99. I believe you can convert it to srfi 99 without much trouble. Arthur _______________________________ Hi, I wanted to represent movement of an object as something that has already happened, without having to worry about time. So I wanted to play around with streams for that, the srfi41 to be exact. Originally I thought, well I'll just download the implementation shown in that srfi, then load the syntax-case library, compile it and then just use it. But it's not that easy... That thing uses r6rs module/library system, and r6rs define-record-type. So given that it uses r6rs stuff, Is there an easy way to get it run in gambit, or do I have to implement that srfi41 for gambit? Which I don't mind doing, if there are no other options. Thanks in advance, Pavel _______________________________________________ Gambit-list mailing list Gambit-list(a)iro.umontreal.ca https://webmail.iro.umontreal.ca/mailman/listinfo/gambit-list

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streams srfi41
by Pavel Dudrenov 17 Mar '09

17 Mar '09

Hi, I wanted to represent movement of an object as something that has already happened, without having to worry about time. So I wanted to play around with streams for that, the srfi41 to be exact. Originally I thought, well I'll just download the implementation shown in that srfi, then load the syntax-case library, compile it and then just use it. But it's not that easy... That thing uses r6rs module/library system, and r6rs define-record-type. So given that it uses r6rs stuff, Is there an easy way to get it run in gambit, or do I have to implement that srfi41 for gambit? Which I don't mind doing, if there are no other options. Thanks in advance, Pavel

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[ANN] Gambit-C v4.4.2 released
by gambit＠iro.umontreal.ca 16 Mar '09

16 Mar '09

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