freenode/#lisp - IRC Chatlog

1:55:52 jeosol #vb%otd$_mp!

2:20:58 aeth_ ** NICK aeth

2:21:42 X-Scale` ** NICK X-Scale

2:21:42 mjl_ ** NICK mjl

2:21:42 liberliver1 ** NICK liberliver

2:21:42 travv0_ ** NICK travv0

2:21:46 chewbranca_ ** NICK chewbranca

2:21:46 billstclair_ ** NICK billstclair

2:22:41 remby_ ** NICK remby

3:21:38 aeth_ ** NICK aeth

3:27:30 aeth__ ** NICK aeth

4:12:48 beach Good morning everyone!

4:33:41 remby hello

4:33:54 beach Hello remby.

4:34:18 remby can you do bitmaps in lisp?

4:34:27 beach Sure.

4:34:52 beach Give the keyword argument :ELEMENT-TYPE 'BIT to MAKE-ARRAY.

4:36:01 remby amazing

4:38:41 beach Why is that "amazing"?

4:41:24 edgar-rft Lisp has lots of amazing bits :-)

4:41:49 remby well I was considering how to do that in at least 3 languages and I couldn't do it so easily

4:42:18 aeth now try making a 10D array in at least 3 languages.

4:43:03 remby that should be technically possible? I've not tried past 3 dimesions

4:43:05 beach remby: After you start using Common Lisp, there is typically fewer and fewer reasons to use the languages you knew before.

4:43:56 remby but muh scheme :'-)

4:44:01 aeth remby: in SBCL 2.0.11, SBCL controversially reduced its ARRAY-RANK-LIMIT from 65529 to 256.

4:44:27 remby why was it so high by default?

4:44:36 remby do lots of folks do db stuff?

4:44:44 beach remby: The rank is the number of dimensions.

4:44:49 beach remby: Not the size of the array.

4:44:56 remby yeah

4:45:11 beach There was probably just no reason to limit it before.

4:45:44 aeth Well, you'll probably run out of memory with a 65529D array, but they didn't try to optimize large dimensional arrays before so they didn't really care

4:45:58 aeth once they needed to optimize it, the particular optimization required a cap

4:46:06 remby ah cool

4:46:46 edgar-rft Every bit of a bit-array should have the right to live in its own dimension.

4:47:28 aeth In some implementations it could be e.g. MOST-POSITIVE-FIXNUM, which can be up to 4611686018427387903 on a 64-bit platform if a FIXNUM is represented as 63 bits (62 bits if treated as unsigned)

4:47:32 aeth Good luck making one of those, though

4:47:53 Bike i kind of want to know what kind of application uses a 257 dimensional array.

4:48:10 remby database possibly

4:48:29 Bike what would a database use a high dimensional array for?

4:48:37 beach That would be very wasteful as s representation for just about anything.

4:48:56 Bike https://github.com/sbcl/sbcl/commit/b628f29e3b3651f8a3a83d28f17b9d514e997849 ah, here's the optimization. simpler than the last time i tried to look up the reason for an sbcl change

4:48:59 aeth The larger it is, the more likely you'll want to use something sparse rather than just directly using array indices

4:49:16 remby why's that?

4:49:23 remby isn't this better for cache?

4:49:39 Bike you're not going to fit a 257 dimensional array with appreciable dimensions into a cache, i don't think

4:50:12 remby yeah, I can't really fathom it

4:50:16 Bike if each dimension is 2 long, there are what, 2^257 elements in it?

4:50:31 remby that looks correct

4:51:00 Bike aeth described the change as "controversial" so i want to hear the controversy

4:51:04 Bike i mean assuming that wasn't a joke

4:51:19 aeth (make-array (loop :repeat 255 :collect 1) :initial-element 0)

4:51:30 aeth (make-array (loop :repeat 255 :collect 2) :initial-element 0)

4:51:40 aeth heh, 57896044618658097711785492504343953926634992332820282019728792003956564819968 isn't an index. So already that's too many.

4:52:06 aeth Bike: People complain when limits are lowered, I guess

4:52:17 aeth iirc it was resolved by calculating the memory requirements

4:52:35 beach People should do a bit of thinking before complaining.

4:52:52 beach I guess that's too much to ask.

4:53:18 aeth This is a very practical array, though. (apply #'aref (make-array (loop :repeat 255 :collect 1) :initial-element 0) (loop :repeat 255 :collect 0)) ;-)

4:54:34 Bike btw you know you can do (make-list 255 :initial-element 1) right

4:55:12 Bike i suppose it's not any shorter than the loop golfwise

4:55:44 beach No, but it's more specific, so preferable.

4:55:52 moon-child even most apl implementations limit the rank of an array at 15. I can't imagine why anybody would want anything higher than maybe 7 or 8

4:56:40 remby most apl implementations are proprietary?

4:56:53 remby or maybe this is in the wild

4:56:58 aeth the lowest one that "works" for me is (make-array (loop :repeat 61 :collect 2) :element-type 'bit :initial-element 0)

4:57:03 aeth but it results in a heap exhaustion

4:57:44 moon-child remby: eh, gnu apl caps it at 8 :)

4:58:18 aeth empirically, if sb-index is not increased, then SBCL could get away with using a cap of 63 and using the rest of the bits for something else

4:59:20 aeth moon-child: then APL doesn't let you do this: (make-array (make-list 20 :initial-element 2) :element-type 'bit :initial-element 0)

4:59:53 moon-child aeth: well, depends on the apl impl. April will, since it uses cl semantics

5:02:00 aeth Everything should use CL semantics.

5:03:01 moon-child aeth: http://clhs.lisp.se/Body/v_ar_ran.htm

5:05:55 remby how long is the CL spec actually?

5:09:39 moon-child 1k pages I think? Something like that

5:11:48 beach One quotation says 1350 pages.

5:12:04 ebrasca Good morning!

5:12:13 remby good day

5:12:13 beach Hello ebrasca.

5:25:41 ealfonso is there a way to quickload some packages in a .lisp file before the reader complains about "package X does not exist"?

5:26:40 White_Flame #.(ql:quickload ...)

5:26:58 White_Flame kinda hacky, only useful for scrap prototypes, don't build that into anything

5:28:50 White_Flame oh, the return value will be taken as source code, so: #.(not (ql:quickload ...)) or whatever to eat it

5:32:29 aeth probably just PROGN with a NIL at the end or PROG1 with a NIL at the start

5:40:29 White_Flame .oO( not code golfed enough! ;) )

5:53:37 splittist_ ** NICK splittist

6:30:38 wxie1 ** NICK wxie

6:49:30 grfn` ** NICK grfn