alexandria-devel October 2011

alexandria-devel@common-lisp.net

4 participants
8 discussions

[alexandria-devel] Question about FORMAT-SYMBOL
by Luís Oliveira 26 Jan '13

26 Jan '13

Hello, I often try to support Allegro's modern mode by doing things like (format-symbol t "~A-~A" :foo :bar). We just came across an issue on #quicklisp where a user had set his *PRINT-CASE* to :DOWNCASE and that caused FORMAT-SYMBOL to intern lower-case symbols, thus breaking the idiom I described. Should fix my code to use SYMBOLICATE instead or should FORMAT-SYMBOL use WITH-STANDARD-IO-SYNTAX? Any opinions? -- Luís Oliveira http://r42.eu/~luis

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[alexandria-devel] Add mkstr and simplify of 'symbolicate
by Liam Healy 31 Oct '11

31 Oct '11

I'd like to suggest adding Paul Graham's very useful function #'mkstr, and his #'symb can greatly simplify symbolicate (defun mkstr (&rest args) "Make a string out of the printed representations of the arguments." (with-output-to-string (s) (dolist (a args) (princ a s)))) (defun symb (&rest args) "Make a symbol out of the printed representations of the arguments." (intern (apply #'mkstr args))) (I'd prefer this name, but this definition could just replace symbolicate's.) Thanks, Liam

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[alexandria-devel] [PATCH] add lastcons
by Mathieu Lemoine 30 Oct '11

30 Oct '11

Hi everyone. I made a little addition to the library. The lastcons function... It is very simple and I found myself thinking "that's something that ought to be in alexandria"... Not knowing the exact procedure to commit to the repo (and "git push" give me a "fatal: The remote end hung up unexpectedly" which is to be expected, I guess...), I send you the patch. Mathieu Lemoine.

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[alexandria-devel] patch to fix warning
by Antony 29 Oct '11

29 Oct '11

Hi I'd like to submit the following patch to get rid of the warning "In PROPER-LIST-LENGTH: Unused lexical variable LAST" I use Clozure Common Lisp Version 1.4-r13122 (WindowsX8664) Please check. Thanks, -Antony --- alexandria/lists.lisp 2010-12-10 09:05:44.649536400 -0800 +++ /home/antony/git/thirdparty/alexandria/lists.lisp 2010-12-10 09:25:01.388698100 -0800 @@ -196,7 +196,11 @@ (slow (cons (car list) (cdr list)) (cdr slow)) ,@(when step (list step))) (nil) - (declare (dynamic-extent slow) ,@(when declare (list declare))) + (declare (dynamic-extent slow) + ,@(when declare + (if (and (consp declare) (consp (car declare))) + declare + (list declare)))) (when (safe-endp fast) (return ,ret1)) (when (safe-endp (cdr fast)) @@ -209,7 +213,7 @@ ;; KLUDGE: Most implementations don't actually support lists with bignum ;; elements -- and this is WAY faster on most implementations then declaring ;; N to be an UNSIGNED-BYTE. - (fixnum n) + ((ignorable last) (fixnum n)) (1- n) n)

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[alexandria-devel] reductions
by Cyrus Harmon 29 Oct '11

29 Oct '11

Hi Alexandrians, Clojure has a function that I occasionally find useful, reductions. It's like reduce, only it returns not the last value of calling the two-arg function, but a list consisting of the first element of the input sequence, followed by the result of calling the two-arg with the first and second elements of the input sequence, then the result of calling the two-arg function with the previous result and the third element, and so on... e.g.: CL-USER> (reductions #'+ '(1 2 3 4)) (1 3 6 10) Here's the code. There are probably better ways to do this, but this is at least portable and simple. I think this would be a useful addition to alexandria. (defun reductions (function sequence &rest args) (let ((l (list (first sequence)))) (apply #'reduce (lambda (a b) (let ((val (funcall function a b))) (push val l) val)) sequence args) (nreverse l))) thanks, Cyrus

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Re: [alexandria-devel] Subfactorial is wrong starting from 11
by Mason Smith 29 Oct '11

29 Oct '11

Here is a correct, linear-time implementation of subfactorial: (defun subfactorial (n) "Subfactorial of the non-negative integer N." (check-type n (integer 0)) (if (zerop n) 1 (do ((x 1 (1+ x)) (a 0 (* x (+ a b))) (b 1 a)) ((= n x) a)))) and the corresponding test (deftest subfactorial.1 (mapcar #'subfactorial (iota 22)) (1 0 1 2 9 44 265 1854 14833 133496 1334961 14684570 176214841 2290792932 32071101049 481066515734 7697064251745 130850092279664 2355301661033953 44750731559645106 895014631192902121 18795307255050944540)).

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[alexandria-devel] Scratching an itch: copy-array
by Svante Carl v. Erichsen 29 Oct '11

29 Oct '11

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Hello! I should like to propose a drop-in replacement for copy-array: (defun copy-array (array &key (element-type (array-element-type array)) (fill-pointer (and (array-has-fill-pointer-p array) (fill-pointer array))) (adjustable (adjustable-array-p array))) "Returns an undisplaced copy of ARRAY, with same fill-pointer and adjustability (if any) as the original, unless overridden by the keyword arguments." (let* ((dimensions (array-dimensions array)) (new-array (make-array dimensions :element-type element-type :adjustable adjustable :fill-pointer fill-pointer))) (dotimes (i (array-total-size array)) (setf (row-major-aref new-array i) (row-major-aref array i))) new-array)) My reasons can be seen from the following tests: (deftest copy-array.3 (let* ((orig (vector 1 2 3)) (copy (copy-array orig))) (typep copy 'simple-array)) t) (deftest copy-array.4 (let ((orig (make-array 21 :adjustable t :fill-pointer 0))) (dotimes (n 42) (vector-push-extend n orig)) (let ((copy (copy-array orig :adjustable nil :fill-pointer nil))) (typep copy 'simple-array))) t) I believe that these tests should pass for compliance with the specification of the type simple-array: "The type of an array that is not displaced to another array, has no fill pointer, and is not expressly adjustable is a subtype of type simple-array." In other words: I find it quite astonishing if the copy of a simple-array is not a simple-array itself. I am grateful for comments and, should you find this acceptable, directions how to proceed. Best wishes Svante P.S.: You can also reach me as 'serichsen' on #lisp at freenode IRC. - -- Svante Carl v. Erichsen Wentorfer Str. 96 21029 Hamburg +49-(0)40-34923721 +49-(0)160-6941474 Svante.v.Erichsen(a)web.de -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.17 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAk5vT3cACgkQFZBb0npmKsxo6wCfRTFqUgYFpH1mc6kX2f7iiMz7 K74Anj9MI8rsndscZyQLYQ0wznQx82+Z =AnI4 -----END PGP SIGNATURE-----

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[alexandria-devel] (circular-tree-p '#1=(#1#))
by Anton Kovalenko 29 Oct '11

29 Oct '11

Hi, Alexandria developers: CIRCULAR-TREE-P has an unfortunate corner case, causing it to overflow the stack (seen and repoted at #lisp for '#1=(#1#), but if I understand it correctly, having a subtree like that can be dangerous as well). The problem is caused by the end-test (of the outer DO) being run before the body has a first chance to check for (member slow seen). Moving endlist into the end of the body seems to fix it. Quick-and-dirty illustration is at <http://paste.lisp.org/+2OHW>. -- Regards, Anton Kovalenko +7(916)345-34-02 | Elektrostal' MO, Russia

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alexandria-devel October 2011