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Re: [gambit-list] handling of macros
by Christian 14 Nov '05

14 Nov '05

I wrote: > Is there an eval to which I could give the current context (as a parameter)? but I was meaning to say, "(as an argument)?". I have yet to get used to use "parameter" only for those dynamic arguments created by make-parameter. Christian.

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handling of macros
by Christian 14 Nov '05

14 Nov '05

Hello Some questions: (the first two of those may be rather general scheme philosophy questions) - why are DSSSL style argument declarations not allowed in define-macro? - why is there no (define-macro foo (lambda(...)...)) form? Is there a lowlevel variant for setting runtime and compiletime macro bindings to some lambda? - is there a way to get at the converter lambda from a (runtime-)macro definition? - I need a way to unset a macro definition, so that the corresponding name can be used as normal function/variable binding from there on. - I'd like to be able to scan a namespace for all bindings and macro bindings. For example for readline completion. (And to be able to remove all runtime macros.) - how can I macro-expand code with the original context? Until now I've used (caddr (##decompile (eval `(lambda() ,code)))) but code is eval'ed in a new lexical context of course. (I haven't understood how to use ##macro-expand. I would be grateful for any help for understanding the sources. How do the cte (=compile-time environment?) and such work? What's the exact concept?) I want macro expansion for writing macros which expand their arguments before working on them. For playing with optimizations (kind of like optimizing mini-compilers). - is there a way to preserve the line/column numbering of source code which is "wrapped" by macros? For something like for example (receive (a b) (code1) code2) it would be nice if when an error happens in code1 or code2, the error message didn't just mention the line/column of the opening paren of the receive form, but the line/column where the relevant part of code1 or code2 is in the original file. Thanks, Christian.

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Bugs in gambit 4.15
by david rush 14 Nov '05

14 Nov '05

two problems I have noticed, but done little in the way of research or remediation: 1 - gsc & gsi when built for solaris 2.6 won't run in the xemacs shell window. No problems in an xterm 2 - (display '(foo bar)) comes out as foobar - I don't know if this is valid RnRS or not, but every scheme I've used has put spaces in between, including gambit 3.0 sorry for the lame bug report, but I figure it's better than nothing david rush -- DIsruptive Technology!

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Extended parameter list syntax
by Marc Feeley 14 Nov '05

14 Nov '05

In the upcoming beta 16 I have extended the DSSSL style parameter lists to better handle rest parameters when keyword parameters are used. The DSSSL syntax for the parameter list is formal-argument-list = reqs opts rest keys where each part can be empty. Thus the rest parameter must come before any keyword parameters, such as (define f (lambda (a b #!rest r #!key x y) (list a b x y r)) a and b are required parameters, x and y are keyword parameters and r is the rest parameter. In DSSSL the rest parameter will contain the keyword parameters, it is not an error if other keywords are passed, and there must only be keyword/value pairs after the required parameters. The DSSSL semantics cannot handle keywords that come before other non- keyword parameters. But this would be convenient for forms where the last parameters are a sort of body in the scope of the keyword parameters. A straightforward example is a set of functions to generate HTML. It would be nice to be able to do: (table cellspacing: 0 cellpadding: 0 (tr (td "foo") (td "111")) (tr (td "bar") (td "222"))) The DSSSL syntax for parameter lists has been extended to allow the rest parameter to come after the keyword parameters, i.e. formal-argument-list = reqs opts rest keys ; standard DSSSL | reqs opts keys rest ; Gambit extension When the rest parameter comes after the keyword parameters, it will be bound to all the parameters after the keywords (i.e. it does not contain the keywords). It is an error if a keyword that is not in the parameter list is passed. Here is an example (define g (lambda (a b #!key x y #!rest r) (list a b x y r)) (f 11 22) => (11 22 #f #f '()) (f 11 22 y: 33) => (11 22 #f 33 '(y: 33)) (f 11 22 y: 33 y: 44) => (11 22 #f 33 '(y: 33 y: 44)) (f 11 22 y: 33 z: 44) => (11 22 #f 33 '(y: 33 z: 44)) (f 11 22 y: 33 888 999) => error (g 11 22) => (11 22 #f #f '()) (g 11 22 y: 33) => (11 22 #f 33 '()) (g 11 22 y: 33 y: 44) => (11 22 #f 33 '()) (g 11 22 888 999) => (11 22 #f #f '(888 999)) (g 11 22 y: 33 888 999) => (11 22 #f 33 '(888 999)) (g 11 22 y: 33 z: 44) => error Moreover, in beta 16, macros can use the DSSSL and extended parameter list syntax. Marc

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Shared libraries
by Pupeno 11 Nov '05

11 Nov '05

Can I use a shared library made with gambit-c without having the linkfile of that shared library ? I am working on the case where I have shared library A which gets installed on /usr/lib/libA.so and I have a program B which uses libA.so (-lA when linking with gcc). Thank you. -- Pupeno <pupeno(a)pupeno.com> (http://pupeno.com)

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flat vs incremental link
by Pupeno 10 Nov '05

10 Nov '05

Hello, What is the difference between flat an incremental link files ? Thank you. -- Pupeno <pupeno(a)pupeno.com> (http://pupeno.com)

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One other thing to help builders
by Pupeno 09 Nov '05

09 Nov '05

One other thing that can be added to Gambit-C to help automatic builders is a '-v' parameter that prints the name and version of the compiler (without colors or anything, so it is easily parseable). -- Pupeno <pupeno(a)pupeno.com> (http://pupeno.com)

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Suggested change to how errors are displayed
by Bradley Lucier 06 Nov '05

06 Nov '05

Marc: In my array code I do lots of things like: (define (Interval-dimension interval) (or (and (not (Interval? interval)) (error "Interval-dimension: argument is not an interval: " interval)) (##Interval-dimension interval))) If I make a mistake and pass a large object that is not an Interval (like an array with a few million elements in it) to Interval- dimension, the code in _repl.scm writes out the whole argument to error and I have to try to hit ^C really, really fast before the location of the error scrolls off the screen. I think it would be better to change the code for (##display- exception exc port) in _repl.scm to something like ((macro-error-exception? exc) (##display (macro-error-exception-message exc) port) (##for-each (lambda (arg) (##newline port) (##write arg port ##error-arg-write-width)) (macro-error-exception-parameters exc)) (##newline port)) and define (define ##error-arg-write-width 72) (set! ##error-arg-write-width ##error-arg-write-width) outside that function. Now I get nice error messages like > (set! ##error-arg-write-width 120) > (load "convex2.scm") *** ERROR IN build-Array, "../generic-arrays.scm"@472.5 -- build- Array: accessor is not a procedure: #<Array-base #4 domain: #<Interval #5 lower-bounds: #(0 0) upper- bounds: #(256 256)> accessor: #<procedure #6> setter: # and I can work with this ;-). Brad

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gc problems with streams/recursions
by Christian 31 Oct '05

31 Oct '05

Hello While playing with streams, I think I've noticed that the stream "head" is not garbage collected while traversing the stream even if it is not referenced by user data structures anymore. There also seems to be a (independent?) problem releasing memory when streams are long (thus recursion is deep). I'm getting out of memory errors when "there shouldn't be", and need to run (##gc) manually to be able to continue calculations (entering ,c in the debugger resumes calculation correctly): it looks like gambit is starting to fill up all available memory if the recursion depth is bigger than something between 20000 and 35000. The two issues happen in both interpreted and compiled code. $ ulimit -S -v 300000 $ gsc > ; (compile-file "test.scm") > (load "test") > (test 35000) repeat the test call several times, it will give *** ERROR IN ##bignum.make -- Heap overflow after about 10 invocations. Same thing with > (test-2 35000) This can be repeated "forever" without hitting out of memory errors: > (test 20000) or this > (test-2 20000) (There are two implementations of stream-take below (one commented out), choosing the other one doesn't change the situation.) This is with Gambit Version 4.0 beta 14 on Debian ppc. With beta 15 on Debian x86, the out of memory situation already happens with a test argument of 25000. What I'm especially wondering is this: the output list from take only needs about 600000 bytes. So if the stream would be deallocated while stream-take is still walking it, much longer streams should be possible (at least 10 times longer). Do you have an explanation or a solution? Thanks Christian. ;; test.scm (declare (block) (standard-bindings) (extended-bindings) ) ;; stream library (define *stream-strict* #f) (set! *stream-strict* #t) (define @force ##force) (define @promise? ##promise?) (define @car ##car) (define @cdr ##cdr) (define @pair? ##pair?) (define @null? ##null?) (define (stream-force strm) (if (@promise? strm) (@force strm) (if *stream-strict* (error "not a stream: expected promise, got:" strm) strm))) (define stream-car (lambda (strm) (let ((p (stream-force strm))) (if (@pair? p) (@car p) (error "stream-car: not a pair:" p))))) (define stream-cdr (lambda (strm) (let ((p (stream-force strm))) (if (@pair? p) (@cdr p) (error "stream-cdr: not a pair:" p))))) (define (null-stream? strm) (let ((l (stream-force strm))) (cond ((##pair? l) #f) ((##null? l) #t) (else (error "null-stream?: argument out of domain:" l))))) ; (define (stream-take strm k) ;; returns a list, not a stream. ; (if (and (##fixnum? k) (##fixnum.>= k 0)) ; (if (##fixnum.= k 0) ; '() ; (or (and (not (null-stream? strm)) ; (let ((res (cons (stream-car strm) '()))) ; (let iter ((res-tail res) ; (strm (stream-cdr strm)) ; (k (##fixnum.- k 1))) ; (if (##fixnum.zero? k) res ; (let ((p (stream-force strm))) ; (and (##pair? p) ; (let ((res-next (##cons (##car p) '()))) ; (##set-cdr! res-tail res-next) ; (iter res-next ; (##cdr p) ; (##fixnum.- k 1))))))))) ; (error "stream-take: stream too short"))) ; (error "stream-take: k is not a positive fixnum:" k))) (define (stream-take strm k) ;; returns a list, not a stream. (if (and (##fixnum? k) (##fixnum.>= k 0)) (let recur ((strm strm) (k k)) (if (##fixnum.zero? k) '() (let ((p (stream-force strm))) (if (##pair? p) (##cons (##car p) (recur (##cdr p) (##fixnum.- k 1))) (error "stream-take: stream too short"))))) (error "stream-take: k is not a positive fixnum:" k))) (define-macro (scons a r) `(delay (cons ,a ,r))) ;; the actual program (define (fib-stream) (letrec ((strm (scons 0 (scons 1 (let recur ((2behind (let ((s strm)) ;(set! strm #f); make gc possible? no, doesn't help. s))) (delay (let ((a (stream-car 2behind)) (r (stream-cdr 2behind)) ) (cons (+ a (stream-car r)) (recur r))))))))) strm)) (define (fib-stream-2) ;; (misses the first two values of the fib series) (let recur ((pprev 0) (prev 1)) (delay (let ((cur (+ prev pprev))) (cons cur (recur prev cur)))))) (define t #f) (define (test n) (time (set! t (stream-take (fib-stream) n)))) (define (test-2 n) (time (set! t (stream-take (fib-stream-2) n)))) ;;end

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Reentrant calling into Gambit object code
by Marko Cetina 30 Oct '05

30 Oct '05

I'd like to use Gambit-compiled object code from a multithreaded C application. However, I'm unsure if Gambit supports reentrant calling from multithreaded C code. Could anybody help me with this? Thanks a lot, Marko Cetina _________________________________________________________________ Dont just search. Find. Check out the new MSN Search! http://search.msn.click-url.com/go/onm00200636ave/direct/01/

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