January 2011 - alexandria-devel - mailman3.common-lisp.net

[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] Subfactorial is wrong starting from 11
by Sergey Dymchenko 23 Jan '11

23 Jan '11

Hi! As far as I understand Alexandria uses approximate formula for subfactorial, and it became wrong very fast. Subfactorial of 10 is correct, but for 11 it's wrong. alexandria exact 11 14684571 14684570 12 176214848 176214841 13 2290792960 2290792932

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