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344 discussions

Hashing "object identities"
by Antoniotti Marco 04 Dec '17

04 Dec '17

Hi I am fooling around with a problem that eventually will have to use a hash table on “triples” of “integers” and “structures". Triples I can portably pass to the EQUAL hash table. I cannot use an EQUALP hash table, because I would end up wasting to much time. Here is the rub: my triples <N, O1, O2> need to use the “object identity” of O1 and O2 (two structs). I could switch to an EQL hash table keyed on (HASH-TRIPLE-KEY N O1 O2). How would you proceed (or write HASH-TRIPLE), while staying as much portable as possible? As you well know SXHASH is practically useless. Thanks — Marco -- Marco Antoniotti, Associate Professor tel. +39 - 02 64 48 79 01 DISCo, Università Milano Bicocca U14 2043 http://bimib.disco.unimib.it Viale Sarca 336 I-20126 Milan (MI) ITALY Please check: http://cdac2018.lakecomoschool.org Please check: http://troncopackage.org Please note that I am not checking my Spam-box anymore. Please do not forward this email without asking me first (cum grano salis).

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Re: ML Maintainer wanted
by Sky Hester 02 Dec '17

02 Dec '17

Seems like it would be a good service to keep up. I volunteer, if no one else has already spoken up. -Sky On Nov 30, 2017 5:53 AM, "Hans Hübner" <hans.huebner(a)gmail.com> wrote: Hi, I would like to step down from being the pro@ mailing list maintainer. It is not a lot of regular work (maybe one or two visits to the Mailman page per month to forward or reject a message from a non-subscriber), but it might be that the list needs to be moved or something and I would like to avoid getting into a situation where maintenance is required and I don't have time to do it. Also, I'm not a professional Common Lisp user anymore, so I don't qualify for the list at this point anyway :D Any takers? Thanks, Hans

7 10

Re: ML Maintainer wanted
by Hans Hübner 30 Nov '17

30 Nov '17

2017-11-30 17:13 GMT+01:00 R. Matthew Emerson <rme(a)acm.org>: > Well, I assume the password isn't going to be that for much longer, since > it was accidentally sent out to the mailing list... :-O > Nice one! 30 years of email and I still can't work it out! Sky is nominated to be the keeper of the new password. :) Cheers, Hans

2 1

ML Maintainer wanted
by Hans Hübner 30 Nov '17

30 Nov '17

Hi, I would like to step down from being the pro@ mailing list maintainer. It is not a lot of regular work (maybe one or two visits to the Mailman page per month to forward or reject a message from a non-subscriber), but it might be that the list needs to be moved or something and I would like to avoid getting into a situation where maintenance is required and I don't have time to do it. Also, I'm not a professional Common Lisp user anymore, so I don't qualify for the list at this point anyway :D Any takers? Thanks, Hans

1 0

Optimizing a function over multiple types for its arguments
by Chaitanya Gupta 28 Nov '17

28 Nov '17

While I was working on qbase64[1], I stumbled over a peculiar problem: I wanted it to work as fast as possible when optimized array types (SIMPLE-ARRAY, SIMLPE-BASE-STRING, etc.) were passed to the encoding/decoding routines, but I also wanted to support the more general types. If I defined my core encoding routine like this: (defun %encode (bytes string) (declare (type (simple-array (unsigned-byte 8)) bytes)) (declare (type simple-base-string string)) (declare (optimize speed)) ...) SBCL would produce very fast code, but the function would no longer work for other ARRAY or STRING types: And if I was to redefine the routine with more general types: (defun %encode (bytes string) (declare (type array bytes)) (declare (type string string)) (declare (optimize speed)) ...) The code produced would be significantly slower. My solution to this conundrum was to create a macro that would take all the different type combinations I wanted to optimize and support upfront: (defun/td %encode (bytes string) (((bytes (simple-array (unsigned-byte 8))) (string simple-base-string)) ((bytes (simple-array (unsigned-byte 8))) (string simple-string)) ((bytes array) (string string))) (declare (optimize speed)) ...) and generate code which would dispatch over the type combinations, then use LOCALLY to actually declare the types and splice the body in: (defun %encode (bytes string) (cond ((and (typep bytes '(simple-array (unsigned-byte 8))) (typep string 'simple-base-string)) (locally (declare (type bytes (simple-array (unsigned-byte 8)))) (declare (type string simple-base-string)) (declare (optimize speed)) ...)) ((and (typep bytes '(simple-array (unsigned-byte 8))) (typep string 'simple-string)) (locally (declare (type bytes (simple-array (unsigned-byte 8)))) (declare (type string simple-string)) (declare (optimize speed)) ...)) ((and (typep bytes 'array) (typep string 'string)) (locally (declare (type bytes array)) (declare (type string string)) (declare (optimize speed)) ...)) (t (error "Unsupported type combination")))) If the run-time dispatch incurs a slight penalty, it is more than offset by gains made by using optimized array types, esp. since these routines have to typically visit every element of the given arrays. I was wondering if there was a better way to do this. Have I missed a trick or two? I was reading about the Lisp Interface Library[2] which supports parametric polymorphism, but not sure if it would result in optimized code like the one my macro generates. Chaitanya 1. https://github.com/chaitanyagupta/qbase64 2. https://common-lisp.net/%7Efrideau/lil-ilc2012/lil-ilc2012.html

2 2

lisp.org
by Nick Levine 20 Nov '17

20 Nov '17

Now that we've established why lisp.org and its friends are long-term off air... The website at lisp.org contained a photo of John McCarthy (and nothing else) since the week he died six years ago. What's the message? In contrast take a quick look at (say) python.org, a site devoted to really assisting people to use that language. Do we care, and if we do how do we go about effecting change? - nick

8 8

Can compiler macros make use of type declarations?
by Chaitanya Gupta 09 Nov '17

09 Nov '17

Let's say I have created a function called `FOO`: (defun foo (x) ...) To optimize this function, I write a compiler macro. Can I make use of type declarations that users of `FOO` might have made for the argument `X` that is passed in to it? That is, let's say `FOO` is used like this: (let ((a (something-that-returns-an-integer))) (declare (integer a)) (foo a)) The compiler macro for `FOO` cannot make any optimizations on the value of `A`, but can it take advantage of the fact that `A` is declared as in `INTEGER` here? Chaitanya

7 15

ALU websites
by Nick Levine 12 Oct '17

12 Oct '17

I am concerned that alu.org (Association of Lisp Users), lisp.org and international-lisp-conference.org are all offline, and have been for at least several weeks. The first two of these didn't really serve anything of use but the ILC site contained proceedings of several past conferences and shouldn't be lost. Does anyone know what's going on? I can't write directly to the ALU because its site is down and so there's no contact list (and I imagine emailing @alu.org is like talking to a black hole). - nick

6 14

In search of Road to Lisp Survey archive
by Ken Tilton 29 May '17

29 May '17

Did anyone happen to snag a backup of the ALU/Cliki Road to Lisp survey responses? I am thinking about resurrecting/hosting that. -- Kenneth Tilton http://tiltontec.com/

3 6

before and after methods
by Didier Verna 20 May '17

20 May '17

Hi! Does anyone know why the non-standard built-in method combinations do not support before and after methods? Thanks. -- Resistance is futile. You will be jazzimilated. Lisp, Jazz, Aïkido: http://www.didierverna.info

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