freenode/#lisp - IRC Chatlog

21:19:37 pjb aeth: (length (remove-if-not (function symbol-plist) (let (l) (dolist (p (list-all-packages) (remove-duplicates l)) (do-symbols (s p) (push s l)))))) #| --> 306 |#

8:22:43 loke jdz: I thought it was more like remove-if-not?

3:42:34 asarch (remove-if-not #'(lambda (x) (= 0 (mod x 2))) '(1 2 3 4 5 6 7 8 9 10))

19:18:01 Xach (let ((in (remove-if-not test list)) (values in (set-difference list in)))))?

19:18:47 Xach (values (remove-if-not test list) (remove-if test list))?

3:49:18 russellw FAQ: 'If using REMOVE and DELETE to filter a sequence, don't use the :test-not keyword or the REMOVE-IF-NOT or DELETE-IF-NOT functions. Use COMPLEMENT to complement the predicate and the REMOVE-IF or DELETE-IF functions instead.' - a curious recommendation. Is there a reason for it?

6:22:38 no-defun-allowed REMOVE-IF-NOT was "deprecated" but no one listened

6:26:41 beach Though, using :TEST-NOT with REMOVE-IF-NOT might not be such a good idea.

6:27:38 beach Heh, (remove-if-not ... :test-not (complement ...))

6:29:16 jackdaniel conceptually remove-if-not is simpler to me (but name is unfortunate - it should be FILTER) - so it picks elements matching the predicate

6:29:58 no-defun-allowed remove-if-not is less abstract

12:50:47 beach REMOVE-IF and REMOVE-IF-NOT are fine, because REMOVE means non-destructive.

12:50:55 dlowe right. As unwieldy as REMOVE-IF-NOT is, it is really obvious what it does

1:19:17 no-defun-allowed isn't remove-if-not also deprecated?

1:20:40 no-defun-allowed so to really be in good form, your code better not use remove-if-not or importing outside defpackages :P

1:26:49 aeth So do you do (remove-if (complement #'evenp) #(1 2 3 4)) and future-proof your code against a removal that probably won't happen or do you do (remove-if-not #'evenp #(1 2 3 4)) and get a faster program?

14:15:56 lukego Verilisp looks awesome in the ECLM sense. Like somebody who wanted to build hardware just decided to use Lisp and bloody well did it. Code looks funky to a Lisper though :-) giving closing parens their own lines like C braces, defining functions like REMOVE-IF-NOT and EXPT with comments thinking they are not already built in..

16:39:31 jackdaniel this is a good question for clschool (again ,p). remove-if-not takes two arguments: a predicate and a sequence

16:40:43 jackdaniel so remove-if-not returns a sequence with all elements in it which met the predicate

16:42:16 pfdietz remove-if-not is like the function filter in scheme

16:43:53 pfdietz One thing to be clear about: remove-if-not is nondestructive. It does not modify its argument (although the return value may share structure with that argument).

16:44:37 jackdaniel mrblack: remove-if-not applies function at-loc-p to elements which are in the second argument

16:50:23 Bike remove-if-not calls at-loc-p.

16:52:19 pfdietz remove-if-not calls at-loc-p on each element of the sequence. For each call, obj is bound to that element.

17:02:09 Bike remove-if-not calls its function argument on each element of the list it's given in the same way. so that's where the obj argument comes from.

17:04:10 mrblack what is the remove-if-not function argument?

17:05:06 mrblack so remove-if-not gets its argument from the very function it is calling?

17:05:58 Bike No. Listen. (remove-if-not #'at-loc-p objs) is a function call. the REMOVE-IF-NOT function receives two arguments, #'at-loc-p and objs. #'at-loc-p is a function and an argument. that's the "function argument" i meant.

17:06:26 Bike So with (remove-if-not #'at-loc-p objs), remove-if-not will call the at-loc-p function on each element of the objs.

17:22:47 mrblack remove-if-not is excecute first because it's function making the call?

17:24:38 pfdietz Execution falls down into the body of the labels form, which is the call to remove-if-not. THAT function then calls at-loc-p on each element of the sequence objs.

17:25:28 pfdietz And the value returned by the call to remove-if-not is the value returned by the labels form, and then from the call to objects-at.

21:44:17 it3ration The names of things seem super antiquated compared to Clojure (aka, remove-if-not instead of filter, etc)

7:46:27 beach "The names of things seem super antiquated compared to Clojure (aka, remove-if-not instead of filter"

7:52:18 elderK I like the name remove-if-not. It's clear.

4:34:16 pillton ACTION likes remove-if-not.

7:14:28 no-defun-allowed use that or its opposite, remove-if-not

11:52:41 shka__ just use remove, remove-if, remove-if-not or whatever works

19:35:27 phoe I can do it via (remove-if-not (curry #'eql thing) list) but I wonder if there's a shorter way.

6:59:53 phoe (remove-if-not (curry #'eq 'foo) list :key #'typep) sounds way too verbose.

7:02:50 |3b| (remove-if-not (rcurry 'typep type) list)?

0:50:59 aeth shouldn't that be remove-if-not?

18:13:01 phoe (remove-if-not #'evenp '(1 2 3 4 5 6 7 8))

18:13:02 selwyn (remove-if-not #'evenp '(1 2 3 4 5 6 7 8 9))

0:54:46 aeth The CLHS search doesn't seem to support my favorite function, remove-if-not

0:56:24 aeth (remove-if-not is the subject of an intense tabs-vs-spaces-level debate over whether or not it should be used because it is probably the most common of the deprecated functions)

1:06:02 Xach remove-if-not works now

1:07:03 Xach there is no debate, remove-if-not is fine to use

1:17:36 aeth It looks like people talked about the topic 2-3 times in the past year here. https://irclog.tymoon.eu/freenode/%23lisp?from=2018-05-16T21%3A15%3A14&to=2019-05-17T09%3A15%3A14&search=remove-if-not&by

1:17:50 no-defun-allowed remove-if and remove-if-not are extraneous just do (loop for item in list when (funcall test item) collect item)