alexandria-devel

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184 discussions

[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

5 7

[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.

3 4

[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)

2 1

[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

3 3

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)).

4 4

[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

2 1

[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

1 1

[alexandria-devel] [RFC] collect-duplicates
by Andreas Fuchs 07 Dec '10

07 Dec '10

Hi there, Prompted by a discussion on #lisp, I've made the following collect-duplicates function: Takes a sequence and a test, and returns as two values a sequence of duplicates and a sequence of the duplicate count (matching their sequence type to the input sequence's). (defun collect-duplicates (sequence &key (test #'eql)) ;; This will work only for TESTs that are valid hash tests: (let ((dupes (make-hash-table :test test)) (known (make-hash-table :test test))) (map nil (lambda (elt) (if (gethash elt known) (incf (gethash elt dupes 1)) (setf (gethash elt known) t))) sequence) (let ((duplicates (make-sequence (class-of sequence) (hash-table-count dupes))) (counts (make-sequence (class-of sequence) (hash-table-count dupes))) (i 0)) (maphash (lambda (k v) (setf (elt duplicates i) k (elt counts i) v) (incf i)) dupes) (values duplicates counts)))) Issues that I see with it: * Needs a :key argument. * :test should allow for non-hash-table tests, as well. * (class-of ...) is not really a good idea, as it doesn't preserve the element type for arrays. If I fixed these issues, would there be interest in having this function in alexandria? Cheers, -- Andreas Fuchs, (http://|im:asf@|mailto:asf@)boinkor.net, antifuchs

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[alexandria-devel] [patch] Support for case-sensitive lisps
by Andreas Fuchs 23 Sep '10

23 Sep '10

I just tried to load alexandria in Allegro CL 8.2's mlisp, and it fails to define types with the correct names there. I'm attaching a patch that does two things: * Make format-symbol accept a string designator (so we can use uninterned symbols for format strings, which yields the correct symbol names independent of case mode), and * use this in types.lisp to create the right type names. I hope you like it (-: Cheers, -- Andreas Fuchs, (http://|im:asf@|mailto:asf@)boinkor.net, antifuchs

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