May 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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