Novembre 2005 - Gambit-list - mailman.iro.umontreal.ca

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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