May 2009 - iterate-devel - mailman3.common-lisp.net

[iterate-devel] Inaccurate *env* for Macroexpansions
by Russ Tyndall 20 May '09

20 May '09

Howdy List, I was having problems when using iterate with the arnesi call/cc codewalker, because variables bound by iterate were not in the environment of any macros in an iterate body form. The codewalker therefore gets that foo is an unbound variable in the iter clause below. To mitigate this, I patched iterate to update the *env* variable to reflect any bindings that iterate is going to make (in sbcl only ATM). Pulling some code from (bsd licenced) http://common-lisp.net/project/bese/repos/arnesi_dev/src/lexenv.lisp, I could probably write an implementation of the two methods I added in all the arnesi supported environments (lispworks /clisp /allegro /cmucl), but I have no way of testing these, so for now I stuck with a tested implementation for sbcl. The semantics of this are fairly straightforward, in that any variable declared textually before a macro call will appear as a lexical variable in the environment passed to the macroexpansion. (loop for foo upfrom 0 while (= foo 0) collect (funcall (lambda () (arnesi:with-call/cc foo)))) => (0) (iter (for foo upfrom 0) (while (= foo 0)) (collect (funcall (lambda () (arnesi:with-call/cc foo))))) => Before my patch this throws unbound variable foo exception / lexical environment is empty After my patch this "correctly" returns (0) Cheers, Russ New patches: [update environment with iterate produced variables Russ Tyndall <russ(a)acceleration.net>**20090520185521 Iterate produces variable bindings that are useful/necessary to macros expanding inside of an iterate body. This particularly effects other codewalkers (such as arnesi). We want (if possible) to update the env we expand macros in to reflect any variables that iterate is lexically binding. ] { hunk ./iterate.lisp 655 +(defgeneric lexical-variables (environment) + (:documentation "Return the names of all the local variables + in ENVIRONMENT. Does not return neither symbol-macrolets nor + ignared variables.") + (:method ((env T)) ())) + +#+sbcl +(defmethod lexical-variables ((environment sb-kernel:lexenv)) + (loop for var-spec in (sb-c::lexenv-vars environment) + when (and (atom (cdr var-spec)) + (not (and (typep (cdr var-spec) 'sb-c::lambda-var) + (sb-c::lambda-var-ignorep (cdr var-spec))))) + collect (car var-spec))) + +(defgeneric update-environment (env) + (:method ((env T)) env) + (:documentation "Updates the lexical environment to reflect all of the available + bindings that iterate has thus far created ")) + +#+sbcl +(defmethod update-environment ((env sb-kernel:lexenv)) + (let ((new-bindings + (loop for (sym . _) in *bindings* + unless (or (null (symbol-package sym)) + (find sym (lexical-variables *env*))) + collect (cons sym T)))) + (sb-c::make-lexenv :default env :vars new-bindings))) + hunk ./iterate.lisp 709 + + ;; Iterate produces variable bindings that are useful/necessary to macros expanding inside + ;; of an iterate body. This particularly effects other codewalkers (such as arnesi). + ;; We want (if possible) to update our environment to reflect any variables that + ;; iterate is lexically binding + (setf *env* (update-environment *env*)) + } Context: [first-time-p bugfix: return-code :body must return list of forms Joerg-Cyril Hoehle <hoehle(a)users.sourceforge.net>**20070525141533 if-first-time not declared obsolete documentation strings for (iter:display-iterate-clauses) complete ] [fix defmacro-driver example in manual Joerg-Cyril Hoehle <hoehle(a)users.sourceforge.net>**20070525081443] [Use @:, @. and two spaces between sentences Joerg-Cyril Hoehle <hoehle(a)users.sourceforge.net>**20070525080932 Move section on predicate (first-time-p) outside of gathering clauses Various typos and some clarifications ] [document *list-end-test* removal in FOR...IN+ON Joerg-Cyril Hoehle <hoehle(a)users.sourceforge.net>**20070525074338] [Renamed back to sharpL-reader attila.lendvai(a)gmail.com**20070506100744] [Fix sharpL reader, add :execute to the eval-when to make (load "iterate" :compiling t) work on clisp attila.lendvai(a)gmail.com**20070506100704] [Convert manual to Texinfo. Luis Oliveira <loliveira(a)common-lisp.net>**20060713142915] [make FOR...IN/ON with dotted lists work like LOOP hoehle(a)users.sourceforge.net**20070503130604 More precisely, FOR ON accepts dotted lists, FOR IN errors out. As a result, iterate::*list-end-test* was eliminated. Behaviour is now constant and does not depend on some special variable. Note: Documentation not yet updated, pending move to Texinfo. ] [walk-tagbody: more testcases Joerg-Cyril Hoehle <hoehle(a)users.sourceforge.net>**20070503095309] [walk-tagbody must not macroexpand symbol/tags among its statements Joerg-Cyril Hoehle <hoehle(a)users.sourceforge.net>**20070404124132] [add ELSE test cases, remove GNU Arch tag Joerg-Cyril Hoehle <hoehle(a)users.sourceforge.net>**20070503093008] [Clean up #L stuff, do not leave #L enabled after loading iterate attila.lendvai(a)gmail.com**20070426153431] [Set *list-end-test* to 'endp instead of 'atom, so (iter (for foo :in something-non-list)) fails instead of silently exists attila.lendvai(a)gmail.com**20070215151652] [wrap code in progns, to avoid possiblity of multiple nil tags in tagbody Henrik Hjelte <henrik(a)evahjelte.com>**20061025145324] [test to detect bug, more than one nil tag in tagbody Henrik Hjelte <henrik(a)evahjelte.com>**20061025145128] [Added release.sh attila.lendvai(a)gmail.com**20060506155953] [TAG 1.4.3 attila.lendvai(a)gmail.com**20060505134701] Patch bundle hash: 62134238d49a98e5dbfb86589229ec0896284f3d

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[iterate-devel] [ELS 2009] Call for participation
by Marco Antoniotti 20 May '09

20 May '09

Apologies for multiple postings.... ************************************************************************ 2nd European Lisp Symposium (ELS 2009) Milan, Italy, May 27-29, 2009 Universita` degli Studi di Milano-Bicocca www.european-lisp-symposium.org ************************************************************************ CALL FOR PARTICIPATION ********************** REGISTRATION IS OPEN AT www.european-lisp-symposium.org. Check out the updated program. Scope and Program Highlights: ***************************** The purpose of the European Lisp Symposium is to provide a forum for the discussion of all aspects of the design, implementation and application of any of the Lisp dialects. We encourage everyone interested in Lisp to participate. The European Lisp Symposium 2009 program includes presentations of high quality papers about novel research results, insights and lessons learned from practical applications, and educational perspectives, all involving Lisp dialects, including Common Lisp, Scheme, Emacs Lisp, AutoLisp, ISLISP, Dylan, Clojure, and so on. The European Lisp Symposium will feature the following highlights: - Scott McKay of ITA Software will talk about how Lisp use has evolved in his circannual industry work. - Mark Tarver of Lambda Associates will talk about Qi as a viral mutation of the Lisp DNA. - Mauro Pezze` of University of Milan-Bicocca will host a panel on Programmers' Productivity from a Software Engineering point of view. - Joao Pavao Martins and Ernesto Morgado of SISCOG will talk about the role of LISP in the success of SISCOG - Christophe Rhodes will give an unportable tutorial. - Michele Simionato will give a tutorial on Scheme module system and Scheme libraries portability issues across implementations. Social Events: ************** Friday 29th evening, Conference Banquet Saturday 30th morning, Guided tour to the "Futurismo" Exhibit in the center of Milan; 2009 marks the 100th anniversary of the Futurism Manifesto; stretching it, the harbinger of Lisp 50 years later. Program Chair: ************** * Antonio Leitao, Technical University of Lisbon, Portugal Local Chair: ************ * Marco Antoniotti, DISCo, Universita`† Milano Bicocca, Italy Program committee: ****************** * Giuseppe Attardi, Universita` di Pisa , Italy * Pascal Costanza, Vrije Universiteit Brussel, Belgium * Irene Durand, Universite` Bordeaux 1, France * Marc Feeley, Universite` de Montreal, Canada * Ron Garret, Amalgamated Widgets Unlimited, USA * Gregor Kiczales, University of British Columbia, Canada * Scott McKay, ITA Software, Inc., USA * Peter Norvig, Google Inc., USA * Julian Padget, University of Bath, UK * Kent Pitman, HyperMeta, USA * Christian Queinnec, Universite` Pierre et Marie Curie, France * Christophe Rhodes, Goldsmiths College, University of London, UK * Robert Strandh, Universite` Bordeaux 1, France * Mark Tarver, Lambda Associates, UK * Didier Verna, EPITA Research and Development Laboratory, France * JonL White, TheGingerIceCreamFactory of Palo Alto, USA * Taiichi Yuasa, Kyoto University, Japan Registration Fees: ****************** * Students EU100, regular EU220. Registration will include the proceedings, coffee breaks, the symposium dinner and other amenities. Accommodation is not included.

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[iterate-devel] proposed clause (FOR var FROM start BY step LENGTH n)
by Tamas K Papp 01 May '09

01 May '09

Hi everyone, I would like to propose an additional driver clause, that uses the syntax (FOR var FROM start BY step LENGTH n) One would think that one can substitute for this using (FOR var FROM start BY step BELOW (+ start (* step n))) but this has two drawbacks: first, it is inconvenient to use this calculation every time I want to do this, second, rounding errors can creep in for floating-point values, eg: (let* ((n 1000) (step pi) (n-incorrect (iter (for x :from 0 :below (* step n) :by step) (summing 1)))) (- n n-incorrect)) ; gives -1 on my machine Here is the code I wrote to implement it, but since I am not an expert on the internals of iterate, it may be improved; or LENGTH could simply be merged into the current implementation (if that is possible while still preserving the separate counter). (defmacro-driver (FOR var FROM start BY step LENGTH n) "Iteration starting from start, stepping by step, for a total of n steps." ;; Note: reason for this macro is that manual calculation for :below ;; (+ start (* step n)) is tedious, and could also lead to incorrect ;; number of iterations with floating point values. (let ((i (gensym)) ; counts from 0 to (1- n), inclusive (j (gensym)) ; counts from start, by step (kwd (if generate 'generate 'for))) `(progn (with ,i = 0) (with ,j = ,start) (,kwd ,var next (prog2 (when (>= ,i ,n) (terminate)) ,j (incf ,j ,step) (incf ,i)))))) Examples: (iter (for i :from 9 :by 2 :length 5) (collecting i)) ; => (9 11 13 15 17) (iter (generate i :from 9 :by 2 :length 5) (collecting (next i))) ; => (9 11 13 15 17) Can you please include this (or something similar) in the next release? Thanks, Tamas

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