July 2009 - alexandria-devel - mailman3.common-lisp.net

[alexandria-devel] Review cycle 2: SWITCH, ESCWITCH, and CSWITCH
by Nikodemus Siivola 08 Apr '10

08 Apr '10

macro switch ((object &key test key) &body clauses) "Evaluates first matching clause, returning its values, or evaluates and returns the values of DEFAULT if no keys match." macro eswitch ((object &key test key) &body clauses) "Like SWITCH, but signals an error if no key matches." cswitch ((object &key test key) &body clauses) "Like SWITCH, but signals a continuable error if no key matches."

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[alexandria-devel] cdr assoc (now called alist-get)
by John Fremlin 25 Nov '09

25 Nov '09

For http://common-lisp.net/project/cl-irregsexp/ and in fact for many other projects, it is quite handy to have a way of storing key value pairs in a table that is more lightweight than a hashtable, and that preserves ordering. The obvious way to do it in Lisp is to store a list like '((key0 . value0) (key1 . value1) ...) However in the ANSI standard there is no easy way to implement (setf (gethash key table) value). (cdr (assoc ...)) is sufficient for lookup. To that end there is commonly available in extensions a (setf cdr-assoc). I posted one to the list before but I had managed to mangle it utterly in my last edit of it and it didn't work. I hope that was why you Alexandrians ignored me . . . Anyway, one problem with cdr-assoc is that the order of parameters is apparently non-standard. To alleviate this problem I have come back with a new name, alist-get and also ralist-get (for cdr-rassoc, the (value.key) convention). Feedback very much appreciated! (declaim (inline racons)) (defun racons (key value ralist) (acons value key ralist)) (macrolet ((define-alist-get (name get-pair get-value-from-pair add) `(progn (declaim (inline ,name)) (defun ,name (alist key &key (test 'eql)) (let ((pair (,get-pair key alist :test test))) (values (,get-value-from-pair pair) pair))) (define-setf-expander ,name (place key &key (test ''eql) &environment env) (multiple-value-bind (dummies vals newvals setter getter) (get-setf-expansion place env) (when (cdr newvals) (error "~A cannot store multiple values in one place" ',name)) (with-unique-names (store key-val test-val alist found) (values `(,@dummies ,key-val ,test-val) `(,@vals ,key ,test) (list store) `(let ((,alist ,getter)) (let ((,found (,',get-pair ,key-val ,alist :test ,test-val))) (cond (,found (setf (,',get-value-from-pair ,found) ,store)) (t (let ,newvals (setf ,(first newvals) (,',add ,key ,store ,alist)) ,setter))) ,store)) `(,',name ,getter ,key)))))))) (define-alist-get alist-get assoc cdr acons) (define-alist-get ralist-get rassoc car racons))

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[alexandria-devel] darcs patch: Add #.#+ readtime conditional functions.
by asf＠boinkor.net 02 Oct '09

02 Oct '09

Mon Oct 16 10:00:31 CEST 2006 asf(a)boinkor.net * Add #.#+ readtime conditional functions. * This adds functions that can be used in #+#. readtime conditionals, for example: #+#.(alexandria:read-if (find-package :asdf-install)) :yay #+#.(alexandria:read-if-fbound :install :asdf-install :exportedp t) :yay * included in the patch is a commented-out portion that allows the user to activate a #? read syntax. I'm not sure if that fits into the conservativism constraints.

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[alexandria-devel] curry and rcurry -> papply and rpapply?
by szergling 07 Aug '09

07 Aug '09

Hi Alexandrians, I believe curry and rcurry are the wrong names for the current functions in Alexandria. See the following for example, http://srfi.schemers.org/srfi-26/mail-archive/msg00000.html http://srfi.schemers.org/srfi-26/mail-archive/msg00015.html What about papply or partial-apply? Or maybe p-apply? This way, The reversed version might be called rp-apply. Otherwise reverse-partial-apply? I am aware that this is a common usage/mistake in CL, but Alexandria doesn't have to perpetuate this error. An unfortunate downside is breaking backwards compatibility. I'm not sure what Alexandria's policy is regarding this... I'm happy to send patches if this renaming is agreed upon. Theam Yong Chew

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[alexandria-devel] char-digit
by Gustavo 15 Jul '09

15 Jul '09

I find very strange that the ANSI specification defines the function DIGIT-CHAR, but doesn't also define CHAR-DIGIT. It would be nice to have it in alexandria. One can use char-code to implement it, but only assuming that the char-code of alphabetic characters are sequential (which happens very oftenly, I don't know any implementation in which this may not work, but this behaviour is not required by the specification). So, here is my suggestion: (defun char-digit (char &optional (radix 10)) "Takes a character and returns its weight. Signals an error if char is not a digit character in the given radix." (assert (digit-char-p char radix) (char) "Character ~a is not a digit character." char) (let ((char (char-upcase char))) #+(or sbcl clisp ecl cmucl openmcl allegro lispworks corman gcl abcl unicode) (cond ((char<= #\0 char #\9) (- (char-code char) (char-code #\0))) ((char<= #\A char #\Z) (+ 10 (- (char-code char) (char-code #\A)))) (t nil)) #-(or sbcl clisp ecl cmucl openmcl allegro lispworks corman gcl abcl unicode) (parse-integer (string char) :radix radix))) I tested and it works. Well, I am open to suggestions, and feel free to include this code in alexandria as well. Gustavo.

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[alexandria-devel] draft documentation in HTML form?
by Ryan Davis 10 Jul '09

10 Jul '09

Is the alexandria documentation online as HTML anywhere? There was just a case in #lisp where I wanted to send someone a link to hash-table-keys, and the only docs I could spot on http://common-lisp.net/project/alexandria/ is a PDF file. Thanks, -- Ryan Davis Acceleration.net Director of Programming Services 2831 NW 41st street, suite B Gainesville, FL 32606 Office: 352-335-6500 x 124 Fax: 352-335-6506

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[alexandria-devel] [PATCH] Faster WHICHEVER
by Luis Oliveira 03 Jul '09

03 Jul '09

Hello, I wrote some code yesterday that used a few big WHICHEVER forms (with 30 or so possibilities) and that turned out to be a bit slow. The attached patch simplifies the implementation of WHICHEVER and its performance doesn't seem to degrade as the number of possibilities increases. Here are both macro expansions for comparision: CL-USER> (macroexpand-1 `(alexandria:whichever * * *)) (CASE (RANDOM 3) (0 *) (1 *) (2 *)) T CL-USER> (macroexpand-1 `(alexandria::whichever-old * * *)) (LET ((#:FUNCTION940 (LAMBDA () *))) (DECLARE #'#:FUNCTION940) (WHEN (ZEROP (RANDOM 2)) (SETF #:FUNCTION940 (LAMBDA () *))) (WHEN (ZEROP (RANDOM 3)) (SETF #:FUNCTION940 (LAMBDA () *))) (FUNCALL #:FUNCTION940)) T Am I missing some advantage of the more complex implementation? Some timings: CL-USER> (compile nil `(lambda () (loop repeat 1000000 do (alexandria::WHICHEVER-OLD ,@(loop repeat 30 collect '*))))) #<FUNCTION (LAMBDA ()) {10037E64D9}> NIL NIL CL-USER> (time (funcall *)) Evaluation took: 0.937 seconds of real time 0.904057 seconds of total run time (0.904057 user, 0.000000 system) 96.48% CPU 2,498,021,856 processor cycles 558,368 bytes consed NIL CL-USER> (compile nil `(lambda () (loop repeat 1000000 do (alexandria:WHICHEVER ; new version ,@(loop repeat 30 collect '*))))) #<FUNCTION (LAMBDA ()) {1002C1E069}> NIL NIL CL-USER> (time (funcall *)) Evaluation took: 0.033 seconds of real time 0.032002 seconds of total run time (0.032002 user, 0.000000 system) 96.97% CPU 89,029,912 processor cycles 288 bytes consed NIL The darcs patch might be too big for the list because the context goes all the way to the initial revision so I've uploaded it here: <http://common-lisp.net/~loliveira/patches/alexandria-whichever.patch> Cheers, -- Luís Oliveira http://student.dei.uc.pt/~lmoliv/

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