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Invalid Syntax after loading syntax-case
by jadamson＠partners.org 05 Fév '08

05 Fév '08

Dear List, I have the following procedure that takes a list of vectors or a list of lists and flattens the list to create a structure called `f64matrix'. >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> ;;this can be a list of lists, list of vectors, or a flat list ;; it would be better to only write out this error once, instead of three times (define (list->f64matrix lst #!optional rows cols) (letrec ((rows->f64matrix ;; this procedure delegates in the uncertain case of ;; (list->f64matrix lst #f #f) (lambda (lst) ;; is the list a list of lists? (cond ((list? (car lst)) (lol->f64matrix lst)) ;; or is it a list of vectors? ((f64vector? (car lst)) (lov->f64matrix lst)) ;; otherwise it is one row (else (lst->f64matrix lst 1 (length lst)))))) (lst->f64matrix ;; this procedure actually makes the matrix given n rows ;; and m columns and a list (lambda (lst rows cols) (if (= (* rows cols) (length lst)) (make-f64matrix rows cols (list->f64vector lst)) (error "Not enough elements for given dimensions")))) (lol->f64matrix ;; this procedure takes a list of n lists of length m and ;; passes a flattened version of lol to (lst->f64matrix ;; lol n m) (lambda (lol) (let ((rows (length lol)) (cols (length (list-ref lol 0))) (flatlol (flatten lol))) (if (= (* rows cols) (length flatlol)) ;; flatten the list (lst->f64matrix flatlol rows cols) (error "Not enough elements for given dimensions"))))) (lov->f64matrix ;; This procedure transforms a list of n f64vectors of ;; length m into a list and passes it to lst->f64matrix ;; with n rows and m columns (lambda (lov) (let ((rows (length lov)) (cols (f64vector-length (list-ref lov 0))) (flatlov (f64lov-flatten lov))) (if (= (* rows cols) (f64vector-length flatlov)) ;; flatten the vectors into one vector or list (lst->f64matrix flatlov rows cols) (error "Not enough elements for given dimensions")))))) ;; execution starts here: ;; ;; gatekeeper: if rows and columns is #f ;; then send to the delegating procedure rows->f64matrix, whose ;; default function is to set a flat list to the data element of a ;; matrix with one row (cond ((and rows cols) ;; lst->f64matrix only takes lists because if you need to ;; specify rows and columns and your input is a vector, you ;; should just use make-f64matrix (lst->f64matrix lst rows cols)) (else (rows->f64matrix lst))))) >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> This requires `flatten', defined by ;;;;;;;;;;;;;;;;;;;;list.ss;;;;;;;;;;;;;;;;;;;; ;; -*-mode:scheme-*- ;; list operations ;; flatten ;; this macro works on lists, however I encounter some funny behavior ;; since macros don't evaluate their arguments ;;(define-syntax flatten ;; (syntax-rules () ;; ;; base case to stop recursion ;; ((flatten (l1 l2 ...)) (list l1 l2 ...)) ;; ((flatten (l1 l2 ...) l3 ...) ;; (append (list l1 l2 ...) (flatten l3 ...))))) (define (flatten lol) (cond ((null? lol) '()) ((not (pair? lol)) lol) (else (append (car lol) (flatten (cdr lol)))))) ;; vector-list-flatten (define (f64lov-flatten lov) (cond ((null? lov) '()) ((not (pair? lov)) (f64vector->list lov)) ((not (f64vector? (car lov))) (error "f64vector expected")) (else (append (f64vector->list (car lov)) (f64lov-flatten (cdr lov)))))) ;;end list.ss Here's the problem: this (list->f64matrix) compiles just fine when I define `flatten' as a function (flatten works just fine as a function, but I need to work on macros, so I decided to try it as a macro). However, if I copy ~~/syntax-case.scm to gambcext.scm and then compile, I get an "invalid syntax" error during compilation. What changes when I load "~~/syntax-case"? Does the definition of letrec change? I appreciate any comments on the code, as well. Thanks! Joel -- Joel J. Adamson Biostatistician Pediatric Psychopharmacology Research Unit Massachusetts General Hospital Boston, MA 02114 (617) 643-1432 (303) 880-3109 The information transmitted in this electronic communication is intended only for the person or entity to whom it is addressed and may contain confidential and/or privileged material. Any review, retransmission, dissemination or other use of or taking of any action in reliance upon this information by persons or entities other than the intended recipient is prohibited. If you received this information in error, please contact the Compliance HelpLine at 800-856-1983 and properly dispose of this information.

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[ANN] Gambit-C v4.2.0 released
by gambit＠iro.umontreal.ca 04 Fév '08

04 Fév '08

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[Fwd: Re: Hello World segfaults on me]
by David St-Hilaire 04 Fév '08

04 Fév '08

oups forgot to include the gambit-list in my repluy ;) -------- Original Message -------- Subject: Re: [gambit-list] Hello World segfaults on me Date: Sun, 03 Feb 2008 10:15:47 -0500 From: David St-Hilaire <sthilaid(a)iro.umontreal.ca> To: Francisco Listas <francisco.listas(a)gmail.com> References: <8d9da3cf0802030633j40e82a56gdc3e6d55fe53915a(a)mail.gmail.com> Francisco Listas wrote: > I am running Ubuntu 7.10, and I've just installed (using synaptic) Gambit-C. > To try my installation, I just wrote (in file hello.scm) this hello > world program: > > (display "Hello World!\n") > > Running: > gsi hello.scm > > Produces the expected output. > > Running: > gsc hello.scm > > Produces hello.o1 executable file, but when I run it, a segfault occurs: > ./hello.o1 Thats where your error lies. Here is what you should do instead: dave@david ~/temp $ echo '(display "allo tout le monde!\n")' > test.scm dave@david ~/temp $ gsi test.scm allo tout le monde! dave@david ~/temp $ gsc test.scm dave@david ~/temp $ gsi test allo tout le monde! dave@david ~/temp $ I am not 100% sure here but I believe that the .o1 file format is some kind of gambit byte code. To get an executable, you need to do the following: dave@david ~/temp $ echo '(display "allo tout le monde!\n")' > test.scm dave@david ~/temp $ gsc -link test.scm dave@david ~/temp $ gcc test.c test_.c -lgambc dave@david ~/temp $ ./a.out allo tout le monde! dave@david ~/temp $ Hope that could help you! :D David

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AWS, Termite, and Snow
by Joe Hosteny 03 Fév '08

03 Fév '08

Hi all, First of all, let me preface this email with a disclaimer. I'm fairly new (again) to Scheme (last exposure was 10+ years ago in college). I'm still feeling my way around a bit, and have settled on Gambit, Chicken, and PLT, to a lesser extent. What I'm trying to say is - dumb questions may follow! I recently wrote a library to manage a cluster of machines in Amazon's EC2. I'm looking to totally rewrite it, and port it to Scheme in the process. I was also looking at having some facility for managing the cluster from within, with event monitoring via SQS or Termite. Currently, the library does that via polling from a machine external to the cluster. It's not ideal, but was sufficient to get my application working. As a start, I wrote a simple Snow package to do MD5 and SHA1 HMAC calculations (the AWS query string API uses SHA1 signatures). I started to look around for some utilities for URI parsing and encoding for use in Gambit, but didn't seem to find anything. So, first question - is anyone aware of a suitable package for this? Second question - if one doesn't exist, what do people do for regular expression parsing in Gambit? Since I haven't really fleshed out the new architecture, I'm not sure it's a requirement that I host code to both communicate events across the cluster and issue AWS API calls from within the same executable. So I guess an option would be to use Chicken for the HTTP stuff, and Gambit for Termite and making calls to the code written with Chicken (though at that point, it may make sense to just use one of the Ruby or Java libs for that part). I'd prefer not to, if for nothing more than to be able to contribute the AWS portion as a Chicken or Snow package. So, a few general questions follow. From recent mailing list discussions, it sounds like Termite will be targeted towards Gambit only, for the time being at least. Guillaume, is that correct? If not, do you have an idea of when it might be seen on other Schemes (specifically, Chicken or PLT)? Also, does anyone have a feel for what is going on with Snow? It seems like the traffic on the mailing list is a bit slow, and the number of packages is still relatively few. Don't get me wrong - my preference would be to contribute any work back as Snow packages, if at all feasible. That goes for lower level support packages as well, provided that I could find some collaborators. I also intend on making an AMI available with Gambit, Termite and any of the packages I produce pre-installed. Cheers, --Joe www.maraudingrobots.com

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open-input-file, read and fifos
by Adrien Pierard 02 Fév '08

02 Fév '08

First question is "how comes reading a fifo isn't blocking?" % cd /tmp % mkfifo fifo % cat > test.scm (let ((fifo-port (open-input-file "/tmp/fifo"))) (pretty-print (read fifo-port)) (close-port fifo-port)) % gsi test.scm #!eof % echo "hello" > fifo& [1] 70455 % gsi test.scm [1] + done echo "hello" > fifo hello Second question is "Why do I often have a 'device not configured' error with code like the one above?" (Bug not reproduced here, but often happens when I try to read or open where nothing is currently being written yet.) Finally, I would like to know whether we could have a procedure WITH-ERROR-TO-FILE to redirect the error port too. Regards, Adrien -- "I am not a Church numeral; I am a free variable!" (The Scheme Underground) For every complex problem, there is a solution that is simple, neat, and wrong.

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Quasiquote syntax question.
by Blake Winton 02 Fév '08

02 Fév '08

Hello everyone, I'm using Gambit on an iPod Touch, and have run into a small hitch when trying to write a macro. The hitch is that I have no way of typing in a ` on the device. It's just not on the keyboard. I realize that I could use (quasiquote a) instead, but I'm really kind of lazy, and would far prefer to write something like $(a b c). I asked Guillaume Cartier on IRC, and he suggested that it was non-standard but possible. He also mentioned it was undocumented, and so instead of trolling through the code, I thought it might be worth while to ask here first for some pointers. Are there any examples of adding syntax like this to Gambit available? Do I need to edit and recompile the interpreter, or can I hook in to the reader somehow? (I'ld even live with ($ a b c), but I can't seem to get that working either.) Thanks, Blake.

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Threads blocking and IO
by François Magnan 01 Fév '08

01 Fév '08

Hello, I am experiencing a strange bug in my code that would be long to explain. To resume the context, I have many threads running in parallel, some open-process IO, some tcp-server IO and some termite processes. At some point all the threads become blocked indefinitely and the program sleeps forever. I stumbled on the following paragraph in the threads section of the Gambit doc: ``A thread is blocked if it is waiting for a mutex to become unlocked, an I/O operation to become possible, the end of a “sleep” period, etc. '' I think this may lead me to a solution to my bug but I don't clearly understand the statement. Could there be an IO operation that blocks all my threads? Any help would be greatly appreciated. Thank you, Francois Magnan

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direction of a tcp object port?
by Bob McIsaac 29 Jan '08

29 Jan '08

Hi: How does one alter the directionality of a tcp object port? It defaults to input-port which results in an exception for a write form. -Bob (define *server-port* 5603) (define (start-tcp) (define sp (open-tcp-server (list port-number: *server-port* ;;direction: input-output ))) ;;(port-settings-set! (list direction: 'input-output)) (if (port? sp) (display "is-a-port\n") (display "not-a-port\n")) (if (input-port? sp) (display "is-a-input-port\n")) (if (output-port? sp) (display "is-a-output-port\n")) sp)

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FYI: Scheme procedure for Watcom
by Bob McIsaac 28 Jan '08

28 Jan '08

Hi: http://dynamo.iro.umontreal.ca/~gambit/wiki/index.php/Watcom_Makefile_Proce… (written in Scheme) creates an OpenWatcom makefile that has rules for a static library. An example at the bottom of the page shows how to link everything for application.exe As stated in Gambit docs, Watcom is slower than GCC. However, one can still devel with Watcom and tinker with that quirky Msys-mingw only if optimization is necessary at the end of a project. Cheers, -Bob-

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error running with emacs in windows xp
by Aaron Ash 27 Jan '08

27 Jan '08

Hello, When running gambit 4.0b22 (or termite) with and without --enable-gcc-opts compiled in I get an error when I press C-d in the debugger. Here is an interaction log in the emacs *scheme* buffer: Gambit Version 4.0 beta 22 > (wtf) *** ERROR IN (stdin)(a)1.2 -- Unbound variable: wtf ;;;; Note: I press C-d when the first debug prompt appears and this error is raised. 1> *** ERROR IN (stdin)(a)1.2 -- The pipe has been ended. (peek-char '#<input-port #2 (stdin)>) 1> *** ERROR IN (stdin)(a)1.2 -- The pipe has been ended. (peek-char '#<input-port #2 (stdin)>) 1> *** ERROR IN (stdin)(a)1.2 -- The pipe has been ended. (peek-char '#<input-port #2 (stdin)>) 1> *** ERROR IN (stdin)(a)1.2 -- The pipe has been ended. (peek-char '#<input-port #2 (stdin)>) The error keeps looping until I kill the gsi.exe process with the task manager. Any ideas what's going on here? The debug commands still seem to work fine though. ie. ,t ,d etc.

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