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[pro] Sub-function free variable binding differences between Scheme and CL
by Burton Samograd 05 Mar '12

05 Mar '12

Hello, I am curently translating the logic circuit simulator code from SICP into Common Lisp and have run into a snag that I would like to ask about. The Scheme code is as follows from section 3.3.4 (page 223 of my hardcover edition): (define (and-gate a1 a2 output) (define (and-action-procedure) (let ((new-value (locical-and (get-signal a1) (get-signal a2)))) (after-delay and-gat-delay (lambda () (set-signal! output new-value))))) (add-action! a1 and-action-procedure) (add-action! a2 and-action-procedure)) The code basically binds the local function and-action-procedure into a list of functions in a1 and a2 which are then called by another routine later to perform the action when a value is set on the wire. My translated Common Lisp code is: (defun make-and-gate (a1 a2 output) (flet ((logical-and (a b) (if (= a 1) b a)) (and-action-proc () (let ((new-value (logical-and (get-signal a1) (get-signal a2)))) (set-signal output new-value)))) (add-action a1 #'and-action-proc) (add-action a2 #'and-action-proc))) The problem is that the bindings of a1 and a2 in and-action-proc are not being bound to the values of the calling function in the Common Lisp version. This causes the calling of and-action-proc to fail because a1 and a2 are not bound and I am assuming being treated as dynamic (special) variables. I have also tried to define and-action-proc using labels with no difference in results. Is this a total schemantic difference between CL and Scheme? Is every function in Scheme a closure where free variables of sub-functions bound to the calling functions environment? If so, is there a way to emulate this in Common Lisp? I would also like to note that I am currently trying out writing this code using LispWorks Personal Edition, rather than my usual SBCL environment, if that would make any difference. -- Burton Samograd

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[pro] ELS 2012, Zadar, Croatia
by Marco Antoniotti 01 Feb '12

01 Feb '12

Apologies for the multiple postings. PAPER SUBMISSION DEADLINE EXTENDED European Lisp Symposium 2012, Zadar, Croatia, April 30th - May 1st, 2012 http://european-lisp-symposium.org The purpose of the European Lisp Symposium is to provide a forum for the discussion and dissemination of all aspects of design, implementation and application of any of the Lisp and Lisp-inspired dialects, including Common Lisp, Scheme, Emacs Lisp, AutoLisp, ISLISP, Dylan, Clojure, ACL2, ECMAScript, Racket, SKILL, and so on. We encourage everyone interested in Lisp to participate. The main theme of the 2012 European Lisp Conference is "Interoperability: Systems, Libraries, Workflows". Lisp based and functional-languages based systems have grown a variety of solutions to become more and more integrated with the wider world of Information and Communication Technologies in current use. There are several dimensions to the scope of the solutions proposed, ranging from "embedding" of interpreters in C-based systems, to the development of abstractions levels that facilitate the expression of complex context dependent tasks, to the construction of exchange formats handling libraries, to the construction of theorem-provers for the "Semantic Web". The European Lisp Symposium 2012 solicits the submission of papers with this specific theme in mind, alongside the more traditional tracks which have appeared in the past editions. We invite submissions in the following forms: Papers: Technical papers of up to 15 pages that describe original results or explain known ideas in new and elegant ways. Demonstrations: Abstracts of up to 4 pages for demonstrations of tools, libraries, and applications. Tutorials: Abstracts of up to 4 pages for in-depth presentations about topics of special interest for at least 90 minutes and up to 180 minutes. Lightning talks: Abstracts of up to one page for talks to last for no more than 5 minutes. All submissions should be formatted following the ACM SIGS guidelines and include ACM classification categories and terms. For more information on the submission guidelines and the ACM keywords, see: http://www.acm.org/sigs/publications/proceedings-templates and http://www.acm.org/about/class/1998. Important dates: February 15th 2012: submission deadline (extended deadline) March 7th 2012: acceptance results April 30th 2012: Conference opens Program Commitee. Chair: Marco Antoniotti, Università degli Studi di Milano Bicocca, Milan, ITALY Local organizers: Damir Cavar, Eastern Michigan University Franjo Pehar, University of Zadar Damir Kero, University of Zadar Members: Giuseppe Attardi, Università degli Studi di Pisa, Pisa, ITALY Pascal Costanza, Intel, Bruxelles, BELGIUM Marc Feeley, Université de Montreal, Montreal, CANADA Scott McKay, Google, U.S.A. Kent Pitman, U.S.A. Christophe Rhodes, Department of Computing, Goldsmiths, University of London, London, UNITED KINGDOM Robert Strandh, LABRI, Université de Bordeaux, Bordaux, FRANCE Didier Verna, EPITA / LRDE, FRANCE Taiichi Yuasa, Kyoto University, JAPAN -- Marco Antoniotti -- Marco Antoniotti, Associate Professor tel. +39 - 02 64 48 79 01 DISCo, Università Milano Bicocca U14 2043 http://bimib.disco.unimib.it Viale Sarca 336 I-20126 Milan (MI) ITALY Please note that I am not checking my Spam-box anymore. Please do not forward this email without asking me first.

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[pro] Defined but no used variable warning during setf expansion
by Burton Samograd 24 Jan '12

24 Jan '12

Hello, I am wondering if anyone can explain the reason for the defined but not used variable in setf that this code is experiencing: CL-USER> (set-macro-character #\$ (lambda (stream char) (declare (ignore char)) (let ((v (read stream))) (list (get v 'setf-handler-name) v)))) (defmacro defactive (var value &key write-handler read-handler) (let ((setf-handler-name (gensym))) `(progn (defparameter ,var ,value) (defmacro ,setf-handler-name (,var) (let ((read-handler (gensym))) `(let ((,read-handler (get ',',var :read-handler))) (if ,read-handler (funcall ,read-handler (eval ,',var)) ,',var)))) (defsetf ,setf-handler-name (,var) (new-val) (let ((write-handler (gensym))) `(let ((,write-handler (get ',',var :write-handler))) (when ,write-handler (funcall ,write-handler (eval ,',var) ,new-val)) (setf ,',var ,new-val)))) (setf (get ',var 'setf-handler-name) ',setf-handler-name) (setf (get ',var :write-handler) ,write-handler) (setf (get ',var :read-handler) ,read-handler) ,value))) (defmacro setactive (var &key read-handler write-handler) `(progn (when ,read-handler (setf (get ',var :read-handler) ,read-handler)) (when ,write-handler (setf (get ',var :write-handler) ,write-handler)))) (defactive x 0 :write-handler (lambda (old-val new-val) (format t "old: ~A new: ~A" old-val new-val)) :read-handler (lambda (val) (format t "value: ~A" val) val)) ;(setactive x :read-handler (lambda (val) (format t "~A !!! ~A" val))) ;(setactive x :write-handler (lambda (old-val new-val) (format t "~A !!! ~A" old-val new-val))) (defactive d6 (random 6) :read-handler (lambda (val) (let ((old val)) (setf d6 (random 6)) old))) STYLE-WARNING: redefining COMMON-LISP-USER::DEFACTIVE in DEFMACRO STYLE-WARNING: redefining COMMON-LISP-USER::SETACTIVE in DEFMACRO 1 CL-USER> (setf $x 10) ; in: SETF (#:G1129 X) ; (LET* ((#:G1175 X)) ; (MULTIPLE-VALUE-BIND (#:G1176) ; 10 ; (LET ((#:G1177 #)) ; (WHEN #:G1177 (FUNCALL #:G1177 # #:G1176)) ; (SETF X #:G1176)))) ; ; caught STYLE-WARNING: ; The variable #:G1175 is defined but never used. ; ; compilation unit finished ; caught 1 STYLE-WARNING condition old: 0 new: 10 10 -- Burton Samograd http://kruhft.dyndns.org

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[pro] Declarations in compilers (feedback welcome)
by Juan Jose Garcia-Ripoll 30 Dec '11

30 Dec '11

After struggling mentally with this for a few weeks, I would like to have some consultation before I introduce some changes in ECL -- not that I expect many users here, but at least some implementor-fellows and power users of other implementations. My concerns right now relate to how declarations should be used by a compiler, and in particular how declarations interact with SAFETY levels. Please correct me if I am wrong, but I have seen more or less the following approaches [a]- Most implementations blindly believe declarations below a certain safety level. Above it, they seem more or less useless. [b]- SBCL takes declarations (and THE) as type assertions. For instance, in (LET ((Y (FOO X))) (DECLARE (FIXNUM Y))) ...) the assignment to Y would be checked to be a FIXNUM. This means the type declaration is actually enforced and believed and only at SAFETY 0 the checks are dropped (*) In both cases one ends up with a model in which in order to truly believe a declaration and have no extra burden (assertions), one has to drop to SAFETY 0 in all code that is involved with it, which is a mess, because it might inadvertently affect other parts of the code. It is for this reason that I am considering an alternative model for ECL which would grade safety as follows - Type declarations are always believed - SAFETY >= 1 adds type checks to enforce them. - SAFETY = 0, no checks. - SAFETY = 1, the special form THE or additional proclamations on the functions can be used to deactivate the check. As in (LET ((Y (THE FIXNUM (FOO X))) ...) This would allow one to keep most code safe, while deactivating some checks when they are really known to be true (**). Do you think this is useful/useless? The problem I see with this approach is that all code around is written for model [a] or [b], but I could not come up with something more sensible so far. Juanjo (*) Actually the checks are also deactivated when SBCL can infer the type of the value that is assigned to Y. This is somewhat contradictory, because (SETF Y (THE FIXNUM (FOO X))) would still generate a check, but proclaiming FOO to return a FIXNUM would completely bypass the check. (**) Yes, indeed I know that LOCALLY exists for a reason, but it does more than THE. For instance, if I (LOCALLY (DECLARE (SAFETY 0)) (THE FIXNUM (FOO (SLOT-ACCESSOR X)))... this influences the safety of the code that accesses a structure, which is not good. P.S.: Thanks to Paul Khuong for pointing out that SBCL behaves differently w.r.t. declarations. -- Instituto de Física Fundamental, CSIC c/ Serrano, 113b, Madrid 28006 (Spain) http://juanjose.garciaripoll.googlepages.com

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[pro] what lisp command line arg parser is good?
by Mark H. David 21 Dec '11

21 Dec '11

Anyone with some thoughts on which command line parser is good to use? There seem to be n of them out there. None really stands out, that I can tell. Must be quicklisp readable, other than that, I don't have any kind of fancy requirements. Just something simple, and reliable. Widely used would be good, and/or well maintained. Any pro tips? Thanks, Mark

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[pro] Keyword arguments and compiler macros
by Juan Jose Garcia-Ripoll 05 Dec '11

05 Dec '11

[Sorry for possible duplicates] I just realized that compiler macros might be too restrictive in some implementations. Take for instance (define-compiler-macro foo (a &key key-arg) ...) This is assuming that FOO is only going to be invoked with _constant_ keyword arguments. I know, I know, most uses will have always one argument or :KEY-ARG, but suppose you want to call (FOO some-value a-non-constant-expression some-other-value)... What is the compiler to do? I _now_ think that the compiler macro processor should simply recognize the failure to parse the form and return the original form, unprocessed, but the implementations I have at hand do not do that. ECL to begin with, but also CCL and SBCL. Any opinions on this? Juanjo -- Instituto de Física Fundamental, CSIC c/ Serrano, 113b, Madrid 28006 (Spain) http://juanjose.garciaripoll.googlepages.com

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[pro] Bignum Arithmetic
by David McClain 04 Dec '11

04 Dec '11

I'm getting more deeply involved in Bignum prime-field and Elliptic Curve computations. Wonder if anyone knows the degree to which the Bignum support in Lisp is enhanced, in the sense that multiple algorithms can be used for, e.g., multiplication, depending on bignum operand sizes. FFT's over integer fields for large numbers, Montgomery multiplication elsewhere, etc.?? I just reviewed GnuMP docs and saw a fairly sophisticated collection of internal optimizations. Would it pay to migrate to GnuMP for specialized applications? Dr. David McClain dbm(a)refined-audiometrics.com

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[pro] Mark Kantrowitz infix.lisp easter egg?
by Alexander Repenning 03 Dec '11

03 Dec '11

Using Mark Kantrowitz old but very handy infix we noticed some peculiar pattern of errors where very basic expressions do not correctly convert infix expressions into prefix ones. The version I just tried was this one: http://www.cliki.net/infix in => pre, red for incorrect "a + 1" => (+ A 1) "s + 1" => S+1 "s - 1" => S-1 "s * 1" => (* S 1) "a + 1.5" => (+ A 1.5) "s + 1.5" => (+ S 1.5) "s + s" => (+ S S) "s + 1 + 1" => (+ S+1 1) "s + 1e1" => (+ S 10.0) Can somebody see a pattern here? AFAIK, the combination of the one letter variables names that are characters D, E, F, L, or S followed by "+" or "-" and then followed by an int does not work. Is this a bug or some very special case that is supposed to work like this for no (to me) obvious reason? If this is bug, how could this have slipped through the net for so many years? I know many people have using this software. I tried various versions of infix.lisp. Are D, E, F, L, or S special tokens? If so, what do they mean, and where are they declared? Confused, Alex ---- test program spitting out the variable names not working ------ This should print nothing: (map nil #'(lambda (Char) (when (symbolp (read-from-string (format nil "#i(~A + 1)" Char))) ;; should be a list, NOT a symbol! (print Char))) "ABCDEFGHIJKLMNOPQRSTUVWXYZ") but prints: #\D #\E #\F #\L #\S Prof. Alexander Repenning University of Colorado Computer Science Department Boulder, CO 80309-430 vCard: http://www.cs.colorado.edu/~ralex/AlexanderRepenning.vcf

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[pro] [ELS 2012] European Lisp Symposium 2012, Zadar, Croatia; call for papers
by Marco Antoniotti 17 Nov '11

17 Nov '11

Apologies for the multiple postings.... ================================================================ European Lisp Symposium 2012, Zadar, Croatia, April 30th - May 1st, 2012 http://european-lisp-symposium.org The purpose of the European Lisp Symposium is to provide a forum for the discussion and dissemination of all aspects of design, implementation and application of any of the Lisp and Lisp-inspired dialects, including Common Lisp, Scheme, Emacs Lisp, AutoLisp, ISLISP, Dylan, Clojure, ACL2, ECMAScript, Racket, SKILL, and so on. We encourage everyone interested in Lisp to participate. The main theme of the 2012 European Lisp Conference is "Interoperabilty: Systems, Libraries, Workflows". Lisp based and functional-languages based systems have grown a variety of solutions to become more and more integrated with the wider world of Information and Communication Technologies in current use. There are several dimensions to the scope of the solutions proposed, ranging from "embedding" of interpreters in C-based systems, to the development of abstractions levels that facilitate the expression of complex context dependent tasks, to the construction of exchange formats handling libraries, to the construction of theorem-provers for the "Semantic Web". The European Lisp Symposium 2012 solicits the submission of papers with this specific theme in mind, alongside the more traditional tracks which have appeared in the past editions. We invite submissions in the following forms: Papers: Technical papers of up to 15 pages that describe original results or explain known ideas in new and elegant ways. Demonstrations: Abstracts of up to 4 pages for demonstrations of tools, libraries, and applications. Tutorials: Abstracts of up to 4 pages for in-depth presentations about topics of special interest for at least 90 minutes and up to 180 minutes. Lightning talks: Abstracts of up to one page for talks to last for no more than 5 minutes. All submissions should be formatted following the ACM SIGS guidelines and include ACM classification categories and terms. For more information on the submission guidelines and the ACM keywords, see: http://www.acm.org/sigs/publications/proceedings-templates and http://www.acm.org/about/class/1998. Important dates: Jan 31st 2012: submission deadline Feb 21st 2012: acceptance results April 30th, 2012 Conference opens Program Commitee. Chair: Marco Antoniotti, Università degli Studi di Milano Bicocca, Milan, ITALY Local organizers: • Damir Ćavar, Eastern Michigan University • Franjo Pehar, University of Zadar • Damir Kero, University of Zadar Members: • Giuseppe Attardi, Università degli Studi di Pisa, Pisa, ITALY • Pascal Costanza, Intel, Bruxelles, BELGIUM • Marc Feeley, Université de Montreal, Montreal, CANADA • Scott McKay, Google, U.S.A. • Kent Pitman, Hypermeta, U.S.A. • Christophe Rhodes, Department of Computing, Goldsmiths, University of London, London, UNITED KINGDOM • Robert Strandh, LABRI, Université de Bordeaux, Bordaux, FRANCE • Didier Verna, EPITA / LRDE, FRANCE -- Marco Antoniotti

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[pro] [ELS 2012] European Lisp Symposium 2012, Zadar, Croatia; call for papers
by Marco Antoniotti 17 Nov '11

17 Nov '11

Apologies for the multiple postings.... ================================================================ European Lisp Symposium 2012, Zadar, Croatia, April 30th - May 1st, 2012 http://european-lisp-symposium.org The purpose of the European Lisp Symposium is to provide a forum for the discussion and dissemination of all aspects of design, implementation and application of any of the Lisp and Lisp-inspired dialects, including Common Lisp, Scheme, Emacs Lisp, AutoLisp, ISLISP, Dylan, Clojure, ACL2, ECMAScript, Racket, SKILL, and so on. We encourage everyone interested in Lisp to participate. The main theme of the 2012 European Lisp Conference is "Interoperabilty: Systems, Libraries, Workflows". Lisp based and functional-languages based systems have grown a variety of solutions to become more and more integrated with the wider world of Information and Communication Technologies in current use. There are several dimensions to the scope of the solutions proposed, ranging from "embedding" of interpreters in C-based systems, to the development of abstractions levels that facilitate the expression of complex context dependent tasks, to the construction of exchange formats handling libraries, to the construction of theorem-provers for the "Semantic Web". The European Lisp Symposium 2012 solicits the submission of papers with this specific theme in mind, alongside the more traditional tracks which have appeared in the past editions. We invite submissions in the following forms: Papers: Technical papers of up to 15 pages that describe original results or explain known ideas in new and elegant ways. Demonstrations: Abstracts of up to 4 pages for demonstrations of tools, libraries, and applications. Tutorials: Abstracts of up to 4 pages for in-depth presentations about topics of special interest for at least 90 minutes and up to 180 minutes. Lightning talks: Abstracts of up to one page for talks to last for no more than 5 minutes. All submissions should be formatted following the ACM SIGS guidelines and include ACM classification categories and terms. For more information on the submission guidelines and the ACM keywords, see: http://www.acm.org/sigs/publications/proceedings-templates and http://www.acm.org/about/class/1998. Important dates: Jan 31st 2012: submission deadline Feb 21st 2012: acceptance results April 30th, 2012 Conference opens Program Commitee. Chair: Marco Antoniotti, Università degli Studi di Milano Bicocca, Milan, ITALY Local organizers: • Damir Ćavar, Eastern Michigan University • Franjo Pehar, University of Zadar • Damir Kero, University of Zadar Members: • Giuseppe Attardi, Università degli Studi di Pisa, Pisa, ITALY • Pascal Costanza, Intel, Bruxelles, BELGIUM • Marc Feeley, Université de Montreal, Montreal, CANADA • Scott McKay, Google, U.S.A. • Kent Pitman, Hypermeta, U.S.A. • Christophe Rhodes, Department of Computing, Goldsmiths, University of London, London, UNITED KINGDOM • Robert Strandh, LABRI, Université de Bordeaux, Bordaux, FRANCE • Didier Verna, EPITA / LRDE, FRANCE -- Marco Antoniotti

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