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4:01:48
pfdietz
A 3-sunflower is a triple of distinct sets such that the pairwise intersection of each of the three pairs equals the intersection of all three.
4:02:27
pfdietz
E-S conjecture said that a sunflower-free collection of subsets of {1,...,n} has size O(c^n) for some constant c strictly less than 2.
4:27:48
krwq
could someone explain this? (array-element-type (make-array '(2 3) :element-type 'float)) => T
4:35:49
pfdietz
Ok, there is no specialized array for element type float. There IS for single-float or double-float. But float is a union of the various float types.
4:36:28
pfdietz
If you tell SBCL you want arrays that can store any float type, it will give you an array that can store any values whatsoever.
4:37:04
pfdietz
upgraded-array-element-type gives the 'least' element type that an implementation has that will support a given type.
4:37:49
krwq
pfdietz: and how do you know what implementation supports (or spec requires)? is it possible to add your own specialization?
4:39:20
pfdietz
A conforming implmentation must support arrays of certains types (bits, chars, base-chars, T), but can support more. There are some constraints.
4:42:31
pfdietz
No conforming implementation is required to support arrays specialized to hold single-floats.
4:46:33
pierpa
though, I think all modern implementations implements single-floats and double-floats as their corresponding IEEE sizes
4:48:12
loke
This one is a little more surprising: (upgraded-array-element-type '(integer 0 300)) ⇒ (UNSIGNED-BYTE 15)
4:50:39
pfdietz
If T1 is a (recognizable) subtype of T2, then (u-a-e-t T1) must be a subtype of (u-a-e-t T2).
4:52:04
pfdietz
In other words, SBCL must also support (unsigned-byte 15) as an actual array element type.
4:52:40
pfdietz
This also has the bizarre consequence that conforming lisps must have arrays with element type NIL.
4:53:17
pfdietz
They are required to support actual array elememt types of char and bit, and the intersection of those types is nil.
4:54:09
pfdietz
Yes. This is required by the standard, at least for recognizable subtypes. Obviously it can't be done in general for SATISFIES types without solving the halting problem.
5:55:31
phoe_air
jackdaniel is also coming, so it's at least five of us Polish people heading towards ELS.
6:20:35
p_l
antoszka: if there is too much traffic at the security, grab vouchers from lost&found office and go through premium
6:53:17
phoe_air
Airport WiFi does not allow SSH connection for some silly reasons. I must expose some kind of SSH tunnel.
6:53:33
phoe_air
As in, I must expose it one day when I come back, so I can connect via port 443 or something.
7:07:25
White_Flame
is there a reasonably faster way to get the string representation of an object through a custom print-object method than (format nil "~a" obj) ?
7:09:45
jackdaniel
depends on what print-object uses. you may use princ in the print-object method and you'll avoid format that way
7:10:52
White_Flame
actually, I remembered write-to-string, and that does the print-object formatting, so that seems to be a reasonable thing to use for this purpose
8:05:14
beach
Some time ago, someone here mentioned a commercial development system for a proprietary language, and that company went bust. But now I can't remember the name of the company. And I can't seem to find it in the logs.
9:00:26
FareTower
beach: I believe famous MIT Schemer Joe Marshall wrote a compiler for REBOL. Despite REBOL being super dynamic, you could optimize for the common case and fall back to the meta-level if that failed.
10:23:56
Xof
I'm on my way to Marbella! I arrive in Malaga at about the same time as SAL9000 (maybe we're on the same flight?)
10:26:32
Xof
so if anyone knows where I should go to meet up and get food, please leave instructions here!
13:42:40
Shinmera
beach: I might be just a little bit biased but I'd probably prefer a conference in Zürich ;)
13:53:29
beach
makomo: However, the most important part of a conference like this is not the talks, but the direct discussions with other participants.
13:54:31
beach
Shinmera: If you hurry up, you could propose your services, and that way we would not have to be co-organized with <programming> as has been proposed.
13:55:17
makomo
beach: i agree. however, it's the only thing from ELS that i have access to, since i can't be physically there
13:56:46
beach
Shinmera: We took a taxi from our hotel in Málaga. It wasn't terribly expensive, and it was a lot easier than to first go to the bus station, take the bus, then get from the bus station to our hotel.
13:57:17
Shinmera
Sure, but the bus station is literally in front of the airport, so it's very convenient
14:23:31
p_l
having spent last week in London, just the weather in Warsaw was gorgeous, and according to jackdaniels the weather in Marbella is similar
14:54:12
Xof
Shinmera: wow, thanks. I've now landed and am waiting for the airport bus, which leaves at 18:00
14:58:31
Shinmera
So, just to be sure, does your bus leave 18:00 CEST (in an hour) or 17:00 CEST (now)
14:59:12
Xof
I have already adjusted to spanish notions of "soon" as well as spanish notions of time
15:10:55
p_l
Shinmera: I've spent last week in London, it was constantly half-raining and even when it wasn't, above ~100m there was monolithic gray sky
15:12:22
Shinmera
ebrasca: Note that rename-file is likely going to fail if you try to rename across devices.
15:15:34
p_l
generalized name for a layer that sits in between actual filesystem implementations and what the software uses
15:16:07
p_l
beach: it's more a plea to consider it now, rather than try to retrofit it, because the latter is much harder
15:17:24
p_l
a minimal VFS in CL could be a function that extracts "device" from a CL path and calls apropriate generic method with it as argument for specialization
15:18:47
p_l
beach: an interesting case - MIT-derived Lisp machines didn't have proper separation of filesystem-related components, this resulted in some file-related applications to be so tightly bound to LMFS they didn't work without it
15:21:10
p_l
Damn, now I wish I actually had managed to take a proper time off for ELS, cause I feel an itch to sit down and write that VFS for you :)
15:23:54
p_l
ebrasca: looks like a start - though it uses HOST as distinguishing component of the path, and you might want to have multiple devices at a host
15:26:58
Xof
the CL pathnames and files chapters suffered in the final stage of the editing of the standard
15:27:31
Xof
those chapters have several internal contradictions and incoherences; they're not quite sure whether they're aiming to be a superset or subset of all things
15:28:04
p_l
(phoe_air) the little bit of knowledge that the Common Lisp community had abouth pathnames has been codified into ASDF and UIOP; the rest is shamanism and black magic
15:28:05
Xof
and then implementors start interpreting things, and users start complaining that the thing they want to do doesn't work how they expect, and...
15:28:50
p_l
There's a significant problem that most of the APIs many people use have all of one field out of all lisp pathname fields
15:29:04
Xof
if you're an implementor, try to do something sensible. If you're a user, please have sympathy with your implementors
15:37:27
pfdietz
I recently found one cannot expect (namestring #p"/foo/bar/baz") to be "/foo/bar/baz".