←2014-05-05 2014-05-06 2014-05-07→ ↑2014 ↑all
00:00:44 <boily> lexande: mapole ↓
00:00:47 <boily> `? mapole
00:00:48 <HackEgo> A mapole is a thwackamacallit built from maple according to Canadian standards.
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00:43:37 <boily> `? ingesorgeco
00:43:38 <HackEgo> ingesorgeco? ¯\(°​_o)/¯
00:43:54 <boily> `coins --french 12
00:43:55 <HackEgo> commantecoin vertielcoin limeubwecoin gaêtancrcoin surguercoin faciencoin reuccoin substrumcoin autopécoin deyroncoin physiavacoin djerontcoin
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00:45:08 <kmc> `coins --canadian-english-insane 10
00:45:09 <HackEgo> refrankedcoin mastaicoin finlidcoin brutcoin capcoin bionarcheterimcoin leurinacoin mimmarkcoin sabillecoin phicablecoin
00:45:25 <Bike> i am all about bionarcheterimcoin
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01:14:02 <fowl> `coins
01:14:03 <HackEgo> chacoin judicacoin lazycoin teqcoin tmlibergcoin mircoin tetneycoin camecoin filecoin frainfcoin etaplecoin wikmanlarcoin foblefoodcoin dvenghacoin hyanickethaxcoin blaccoin watchacoin v--coin monofcoin headcoin
01:27:56 <FreeFull> Why do people still use quicksort when radix sort exists?
01:28:33 <pikhq> Because quicksort has "quick" in the name.
01:28:50 <pikhq> I fail to see how radix sort is relevant though: quicksort is honestly a blatant misnomer.
01:29:06 <pikhq> It's literally got O(n^2) worst case performance.
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01:33:17 <FreeFull> pikhq: It's faster than merge sort on average though
01:33:29 <FreeFull> And merge sort is O(n log n)
01:33:41 <FreeFull> Radix sort is just O(nk) though
01:33:57 <FreeFull> I mean, merge sort is guaranteed O(n log n)
01:34:39 <FreeFull> Radix sort blows quicksort out of the water
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01:42:24 <monotone> Only if k <= log(n).
01:43:13 <monotone> If you have a sparse distribution of numbers over some large range it's going to be very inefficient.
01:43:40 <FreeFull> That's true
01:43:56 <FreeFull> But would quicksort for such a distribution be better than merge sort or even insertion sort?
01:46:12 <monotone> Dunno.
01:46:26 <pikhq> Radix sort is O(nk) but not constant in memory usage.
01:46:34 <pikhq> Shell sort is bitchin'.
01:47:14 <FreeFull> There is in-place radix sort, although it's not quite the same
01:48:13 <pikhq> I think the main thing with quicksort *in particular* is, in general what you want from a sorting algorithm is not absolute fastest time, but rather consistently not-slow time.
01:48:22 <pikhq> Especially when dealing with, say, a library function.
01:48:32 <pikhq> That you Want to be robust against potentially malicious input.
01:49:41 <pikhq> "Usually fast, but sometimes ungodly slow" is not a good thing.
01:53:03 <FreeFull> pikhq: If you have n 128-bit numbers, it's going to take radix sort the same amount of time to sort them no matter what they are
01:53:39 <pikhq> Yes. Radix sort is a good algorithm, and should probably be used when applicable.
01:53:55 <pikhq> My complaints were with quicksort, not radix sort.
01:54:41 <FreeFull> Shell sort seems to have the same asymptotic complexities as quicksort, so simplicity and constant factors would be the thing to consider
01:55:10 <pikhq> Shell sort has worst-case O(n log n).
01:55:19 <pikhq> Erm, wait.
01:55:21 <pikhq> Smooth.
01:55:23 <pikhq> That's what I meant.
01:55:31 <pikhq> Jeeze, I must be sleepy today.
01:55:41 <pikhq> Shell sort is not at all what I meant to recommend. :)
01:56:09 <pikhq> Your being confused at me is very understandable.
01:59:05 <FreeFull> Shell sort isn't stable, but in-place quicksort isn't either
01:59:19 <FreeFull> What sort did you mean then?
02:04:13 <pikhq> Smoothsort.
02:04:36 <pikhq> Or... well. At least something that isn't worst-case suboptimal.
02:04:58 <pikhq> Which is definitely not shell. :)
02:13:53 <FreeFull> Ah, heapsort variation
02:14:06 <FreeFull> That takes advantage of runs
02:14:44 <pikhq> Yep.
02:52:30 <kmc> FreeFull: you can't always use radix at all
02:52:47 <kmc> you might only have pairwise comparison
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03:16:15 <HackEgo> [wiki] [[Suicide]] http://esolangs.org/w/index.php?diff=39462&oldid=17129 * 76.100.81.188 * (+70) Tagged
03:19:07 <Bike> does anyone know who, if anyone, owns the rights to 65xx processors? like, MOS is gone, can anyone make them now?
03:23:04 <HackEgo> [wiki] [[Gerbil]] http://esolangs.org/w/index.php?diff=39463&oldid=23533 * 76.100.81.188 * (+51) Tagging
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03:31:35 <kmc> i should lie and tell people that the Finnish language has case for punctuation and that { is actually considered a lower case version of [
03:31:56 <kmc> or someone can try now to convince me that this is actually true, that might be a fun game
03:38:59 <lexande> wait i thought it was { is the upper case version of [
03:40:31 <lexande> hmm no i guess not
03:57:40 <kmc> `run echo '[{' | iconv -f iso646-fi
03:57:40 <HackEgo> ​Ää
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04:08:18 <Bike> http://arxiv.org/abs/cond-mat/0303625/ neat paper people might like. does CAs!
04:09:53 <lexande> `run echo ']}\|' | iconv -f iso646-fi
04:09:54 <HackEgo> ​ÅåÖö
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05:06:58 <kmc> Bike: you are wrapping a mobius strip of videotape around and around the math/porn part of my mind
05:07:22 <Bike> i... don't know what that means? or where i got video tape nowadays
05:08:17 <kmc> it means mind = blown
05:09:11 <kmc> i saw a VHS rewinder next to a trash can the other day
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05:33:23 <Jafet> Why do people still sort when you can just put it in a replicated nosql cloud
05:33:38 <coppro> sort what?
05:33:47 <Bike> stolen Flickr passwords
05:34:37 <coppro> oh
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05:36:26 <Jafet> And this one?
05:36:55 <coppro> hunter2 obv
05:37:11 <coppro> I assume that's what you use as a password for everything
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06:05:54 <oerjan> `learn Ingesorgeco is when a German is worrying that their money might get cut short.
06:05:55 <HackEgo> I knew that.
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06:34:18 <olsner> Bike: http://www.westerndesigncenter.com/wdc/ perhaps ... but there may be more companies holding licenses to make 65xx chips
06:34:41 <Bike> it's just that the licensor doesn't exist any more far as i can tell
06:34:56 <Bike> legalities are hard
06:35:28 <olsner> yeah, I'm not sure who/what they'd have a license from, presumably commodore (who bought MOS) exists in a shell somewhere
06:36:22 <Bike> patent trolls from beyond :o
06:36:42 <olsner> or, no, they split from commodore, and apparently it was later "liquidated", http://en.wikipedia.org/wiki/MOS_Technology#GMT_Microelectronics
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09:43:18 <slereah_> Is there a C type specific to probabilities?
09:43:31 <slereah_> Floating points are pretty bad at it
09:43:41 <slereah_> Not uniform and bad range
09:44:18 <oerjan> long long int hth
09:44:30 <oerjan> wait
09:44:34 <oerjan> make that unsigned
09:44:47 <oerjan> very uniform.
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10:12:01 <Melvar> Is a long long int 128 bits anywhere?
10:18:14 * oerjan thinks they must have finally fixed the annoying tab bug in IE 11
10:31:59 <oerjan> and also, the address bar suddenly seems not to give the entirely wrong completion suggestions any more...
10:32:44 <Jafet> __int128 is 128 bits everywhere
11:06:21 <mroman_> Melvar: no
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11:07:53 <Jafet> How long must we long for long long long!
11:09:17 <Melvar> mroman_: Would it comply with the standard?
11:09:27 <mroman_> long long is guaranteed to be 64bits
11:09:42 <mroman_> but that's it
11:10:19 <Melvar> mroman_: You mean, exactly 64 bits, not ≥64?
11:10:43 <mroman_> I mean "at least"
11:11:07 <Melvar> Okay, that’s what I would have expected. Thanks.
11:11:12 <Jafet> There is no required integer type required to have an exact bit size
11:11:31 <mroman_> The C standard only defines the manimum range of a long long
11:11:59 <mroman_> *minimum
11:12:31 <Jafet> This is so that WG14 sponsors can make a 32-bit sandwich toaster and advertise support for ISO standard C
11:12:32 <mroman_> You should use int128_t if you wan't exactly 128bits
11:12:41 <mroman_> but I'm not sure how much support compilers have for intN_t
11:13:00 <mroman_> I don't get it why compilers use non-standard stuff like __int128
11:13:06 <mroman_> when they could just use int128_t
11:13:43 <Melvar> mroman_: I was just wondering; I don’t need a 128-bit type for anything.
11:14:00 <mroman_> You better use inttypes .
11:14:20 <mroman_> I don't see a reason to use long long
11:14:27 <mroman_> I don't see a reason to use int for that matter
11:14:36 <mroman_> it's broken
11:15:00 <mroman_> for(int i = 0; i < 10000; i++) { /* hurray, I'm crappy unportable code */ }
11:15:09 <mroman_> *100000
11:15:56 <mroman_> Melvar: My opinion on those regular C types is "They suck"
11:16:00 <Jafet> It's a feature to prevent idiots with obsolete computers from enjoying the software
11:16:09 <mroman_> Exactly!
11:16:22 <mroman_> There's no guarantee an int can hold 100k
11:16:39 <mroman_> on my obsolete computer .
11:17:06 <Melvar> I did once program a microcontroller with a 16-bit int, I think.
11:17:16 <Jafet> Well, the real problem is that int is no longer mapped to machine words by any amd64 compiler (and on most of them, not even long)
11:17:24 <mroman_> int is at least 2^16
11:17:35 <Jafet> So you have people writing int left and right and the compiler has to sign-extend them all
11:17:38 <mroman_> but nobody said it can hold 32bit values
11:17:47 <Jafet> It's p. efficient
11:18:36 <mroman_> well
11:18:44 <mroman_> There's int_fast32_t!
11:19:29 <Jafet> Pretty sure that's still mapped to int to appease the peasants
11:19:37 <mroman_> which, if you use on a 64bit machine probably gives you an int64_t?
11:19:59 <mroman_> which means that you better not rely on 32bit wrap-arounds .
11:20:07 <Jafet> No, I don't know any compiler that maps int to int64_t
11:20:20 <Jafet> I think posix requires int to have at least 32 bits, though
11:20:36 <mroman_> I don't know any compiler that maps int to int64_t
11:20:42 <mroman_> but a compiler is allowed to do so
11:20:58 <Jafet> In practice, it's not going to happen
11:21:16 <mroman_> why not?
11:21:33 <Jafet> It will break milljeeons of programs
11:21:35 <mroman_> I could imagine that int64_t is faster
11:21:48 <mroman_> Jafet: I don't care about breaking millions of crappy written programs .
11:21:50 <mroman_> ;)
11:22:04 <mroman_> If you rely on int to be 32bit you don't know C
11:22:07 <Jafet> Good thing you're not writing compilers, then
11:22:11 <Jafet> Or programs
11:23:14 <Melvar> If one relies on 32-bit wraparounds, it needs int32_t and -fwrapv at least, I believe.
11:23:53 <mroman_> Yeah
11:23:59 <mroman_> wrap-arounds are evil anyway
11:24:12 <mroman_> but what kind of evil stuff were people doing so that the code breaks if int is suddenly 64bit wide?
11:24:36 <mroman_> (relying on wrap-arounds would be one thing)
11:24:55 <Jafet> Not evil, just stupid
11:24:59 <Melvar> ( the Int maxBound
11:24:59 <idris-bot> Can't resolve type class MaxBound Int
11:25:33 <Melvar> Oh, right, it won’t actually be known …
11:25:54 <Jafet> `echo $'#include <inttypes.h>\n#include <stdio.h>\nmain(){ printf("%zu %zu %zu", sizeof(int_least32_t), sizeof(int32_t), sizeof(int_fast32_t)); }\n' > /tmp/a.c && gcc /tmp/a.c -o /tmp/a.out && /tmp/a.out
11:25:54 <HackEgo> ​$'#include <inttypes.h>\n#include <stdio.h>\nmain(){ printf("%zu %zu %zu", sizeof(int_least32_t), sizeof(int32_t), sizeof(int_fast32_t)); }\n' > /tmp/a.c && gcc /tmp/a.c -o /tmp/a.out && /tmp/a.out
11:26:06 <Jafet> `run echo $'#include <inttypes.h>\n#include <stdio.h>\nmain(){ printf("%zu %zu %zu", sizeof(int_least32_t), sizeof(int32_t), sizeof(int_fast32_t)); }\n' > /tmp/a.c && gcc /tmp/a.c -o /tmp/a.out && /tmp/a.out
11:26:07 <HackEgo> 4 4 8
11:26:23 <Jafet> Wow, gcc fucks the peasants
11:27:43 <mroman_> hm?
11:27:51 <mroman_> looks like int_fast32_t is 64bit
11:28:45 <mroman_> although I'm currently reading something about "you can fit more 32bit ints into the cache so it's faster"
11:28:57 <mroman_> You certainly can fit more 32bit ints into a cache line
11:29:25 <mroman_> so...
11:30:40 <mroman_> If you do 32bit computations on 16 integers
11:30:45 <mroman_> they fit neatly into a cache line
11:30:52 <mroman_> wherease 16 64bit integers wouldn't!
11:31:27 <mroman_> well...
11:31:33 <mroman_> Somebody should test that
11:33:54 <mroman_> My gcc is probably 32bit though
11:33:55 <mroman_> hm
11:34:22 <Jafet> Not on itanium
11:36:40 <mroman_> ah
11:36:45 <Jafet> `run echo $'#!/bin/sh\necho "$@" > /tmp/a.c && gcc /tmp/a.c -o /tmp/a.out && /tmp/a.out' > bin/cc && chmod +x bin/cc
11:36:46 <mroman_> they blocked me on the 64bit machine
11:36:46 <HackEgo> No output.
11:37:02 <mroman_> probably due to something important running on it :D
11:37:18 <Jafet> `cc #include <stdio.h>\nmain(){ return 1/0; }
11:37:18 <HackEgo> ​/tmp/a.c: In function ‘main’: \ /tmp/a.c:2:17: warning: division by zero [-Wdiv-by-zero] \ Floating point exception
11:38:30 <Jafet> `cc #include <stdio.h>\nmain(){ puts("\n\n\n"); }
11:38:30 <HackEgo> ​/tmp/a.c: In function ‘main’: \ /tmp/a.c:2:14: warning: missing terminating " character [enabled by default] \ /tmp/a.c:2:1: error: missing terminating " character \ /tmp/a.c:5:1: warning: missing terminating " character [enabled by default] \ /tmp/a.c:5:1: error: missing terminating " character \ /tmp/a.c:5:1: error: expected expression at
11:38:41 <Jafet> `cc #include <stdio.h>\nmain(){ puts("\\n\\n\\n"); }
11:38:42 <HackEgo> No output.
11:39:00 <Jafet> `cc #include <stdio.h>\nmain(){ puts("\\n\\n\\n☃"); }
11:39:01 <HackEgo> ​ \ \ \ ☃
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12:25:31 <FireFly> very snowman
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12:31:02 <HackEgo> [wiki] [[Zero]] N http://esolangs.org/w/index.php?oldid=39464 * Tailcalled * (+1493) Created page with "Zero is a language invented by Tailcalled. It was specifically designed to be literally impossible to program in and execute in the general case. Zero has eight instructions,..."
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12:36:54 <Jafet> Literally
12:40:37 <S1> literally what?
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13:23:14 <HackEgo> [wiki] [[Zero]] M http://esolangs.org/w/index.php?diff=39465&oldid=39464 * FireFly * (+172) +categories
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14:40:38 <ais523> Firefox just upgraded; I had to open the About menu to make sure I hadn't opened Chrome by mistake
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16:25:12 <Bike> kmc: http://pipeline.corante.com/archives/2014/04/21/molecular_printing_of_drug_molecules_say_what.php :catdrugs:
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16:32:34 <Jafet> Peer review. Not even once.
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17:35:27 <myname> i feel dirty using nested wheres in haskell
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17:36:41 <Jafet> Those dirty where nests
17:37:06 <kmc> i wrote some rust code with early return inside a match inside a macro inside a guard
17:41:10 <kmc> match () { _ if match self.lookahead_and_consume(6, |s| s.eq_ignore_ascii_case("public")) { None => return true, Some(r) => r } => go!(to AfterDoctypeKeyword Public), ... }
17:43:43 <ais523> what does go! do?
17:44:07 <ais523> also, I approve of that case-insensitive equality operation
17:44:56 <myname> why is ascii mentioned there?
17:45:04 <myname> does it respect other types of cases?
17:45:22 <kmc> no, it doesn't do Unicode case folding, which is very complicated and also not what's in the relevant spec
17:45:59 <kmc> ais523: it's another macro I defined, a DSL for writing HTML tokenizer actions in a concise way https://github.com/kmcallister/html5/blob/master/src/tokenizer/mod.rs#L475-L543
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17:46:08 <ais523> there are a bunch of ways to do case folding
17:46:12 <ais523> ASCII case folding is at least well-defined
17:46:23 <kmc> well-defined, simple, fast, not locale-dependent
17:48:17 <kmc> the HTML parsing spec mostly doesn't interpret non-ASCII characters
17:48:31 <kmc> because it's not like past software has handled them consistently
17:51:36 <kmc> this is also handy because a parser operating on UTF-8 can do most operations on bytes without decoding them to codepoints
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17:53:57 <kmc> which in turn makes it easier to use SIMD instructions
17:54:37 <ais523> SIMD parsing :-)
17:54:54 <ais523> wouldn't UTF-32 be faster for that, if you had to handle Unicode codepoints, but didn't care about grapheme clusters?
17:55:17 <ais523> although that would probably suffer from caching issues
17:55:38 <kmc> yeah, increasing memory traffic 4x will probably kill other gains
17:55:47 <kmc> and most content comes off the wire as UTF-8 so you would need to convert it first
17:56:05 <kmc> (and basically no content comes as UTF-32; I'm not sure it's even allowed)
17:56:21 <ais523> I want a UTF-graphemecluster
17:56:30 <ais523> even if it's hundreds of bytes per cluster
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17:56:40 <ais523> actually, that's how ncursesw works internally
17:57:22 <kmc> i'm not sure that grapheme clusters are relevant to any part of the web stack
17:58:39 <kmc> high quality text shaping for proportional fonts can map any number of codepoints to any number of (translated, scaled, etc.) glyphs
17:59:28 <kmc> but the input to the shaping library might be a sequence of grapheme clusters? i've forgotten
18:02:06 <kmc> in servo I mean
18:05:06 <ais523_> oh, right, I forgot that Rust is made by a browser company
18:05:08 <ais523_> I was just thinking in general
18:05:16 <kmc> heh
18:06:56 <kmc> I am writing a HTML parser for Servo but I want it to be a generally useful library, which is tricky because browsers have some unusual requirements
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18:10:32 <kmc> I think there are a lot of open questions about API design in Rust generally
18:10:44 <FreeFull> Is Servo Rust's only killer program so far?
18:11:02 <kmc> because of the need to accommodate library users with different memory management strategies, in a safe API
18:11:19 <FreeFull> It seems to be quite influential to Rust's design
18:12:01 <kmc> I think I care more about getting higher-kinded polymorphism after considering its use with lifetime variables
18:12:47 <kmc> FreeFull: well, what do you mean by killer program?
18:12:59 <ais523> FreeFull: it may be the motivating application
18:13:10 <kmc> Servo is probably the second largest program written in Rust, but it's not usable for anything real yet
18:13:10 <ais523> like, aimake is mostly used on NetHack, because that's what I needed it for
18:13:27 <kmc> (it's like 100k SLoC)
18:13:35 <kmc> rustc is like 300k
18:13:42 <ais523> ooh, self-hosting already?
18:13:43 <kmc> including the bundled libs etc
18:13:48 <kmc> ais523: yes, for some years now
18:14:01 <ais523> for Rust, I think that makes sense
18:14:01 <kmc> ais523: the runtime system is also self hosting, which is a lot more unusual
18:14:05 <ais523> there's some debate about whether languages should self-host
18:14:14 <ais523> but something with Rust's aims should probably be able to
18:14:21 <kmc> i mean, not every language is a good choice for writing a compiler
18:14:25 <ais523> exactly
18:14:28 <kmc> so there isn't a general answer to the question of "should you self-host"
18:14:34 <ais523> here, we identify the languages that aren't
18:14:35 <kmc> but yeah, I think for Rust it's a defensible decision at least
18:14:41 <ais523> then write self-compilers in them anyway
18:15:13 <kmc> the compiler still makes heavy use internally of the deprecated refcounted @-boxes
18:15:16 <kmc> :/
18:15:21 <kmc> which have been removed in favor of a Rc<T> library type
18:15:34 <kmc> self-hosting is a big pain when your language is still evolving so rapidly
18:15:54 <ais523> is it possible to change from one to the other in an automated way?
18:15:59 <ais523> like, the syntax for ~-boxes is also changing
18:16:04 <ais523> that's been the big Rust news recently
18:16:12 <kmc> they've done some automated refactorings I know
18:16:15 <ais523> everyone seems to expect a huge outcry, yet it never emerges
18:16:20 <kmc> pcwalton wrote a big perl script
18:16:25 <kmc> ais523: i whined about it in #rust yesterday
18:16:46 <ais523> oh, I was expecting something parsetree-based, but I guess it's hard to preserve comments when doing that
18:16:47 <kmc> 15:36 <@kmc> for f**ks sake
18:16:47 <kmc> 15:36 <@kmc> at this rate in another year Rust will be the SK calculus
18:17:10 <nortti> is there a SK-calculus self-compiler?
18:17:25 <kmc> Rust has a syntactic concept of a "token tree", which is useful for macros and automated refactoring
18:17:37 <kmc> I don't know if other languages have this
18:17:54 <nortti> lisp macros?
18:17:56 <ais523> nortti: there are Unlambda self-compilers
18:18:05 <ais523> which is about as close as you'll get
18:18:10 <ais523> err, self-interps
18:18:13 <kmc> it's a tree of balanced parentheses (and brackets etc.) where the leaves are tokens
18:18:19 <ais523> those are basically SK + C + I/O
18:18:23 <kmc> nortti: yeah, I guess it is similar to manipulating code as S-expressions
18:18:28 <Bike> probably closer to an AST than s-expressions are?
18:19:00 <kmc> but Rust has a lot more expression grammar than Lisp; it's just that you can manipulate code before the stage at which that grammar is implemented
18:19:22 <kmc> but I'm fond of pointing out that Lisp also secretly has a lot of expression grammar
18:20:18 <kmc> FreeFull: Servo has been influential to Rust's design, certainly, but I think somewhat less than one might expect
18:20:23 <Bike> and not-secretly. the BNF for loop is a couple pages long
18:20:29 <kmc> heh
18:20:51 <nortti> loop really is a beast
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18:21:21 <Bike> and shivers's loop is the same way, so there go any "uh but loop isn't REALLY lisp" crapola
18:21:38 <kmc> there are only a few people who do lots of work on both Rust and Servo
18:21:55 <Bike> r u one
18:22:12 <kmc> no
18:24:36 <kmc> i've only landed a few patches to rust
18:24:43 <kmc> opened a lot of bugs though :P
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18:25:39 <kmc> i basically consider compiler bugs part of the fun
18:25:44 <kmc> i've only hit a few really nasty ones, though
18:28:04 <FreeFull> I've only hit one so far
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18:49:32 <kmc> http://www.pcworld.com/article/2150775/amd-announces-skybridge-chips-to-bring-together-x86-and-arm.html
18:53:29 <olsner> hmm, how would that work?
18:54:34 <olsner> oh, it's not x86+arm in one cpu chip, but different pin-compatible x86 and arm cpus, I guess
18:55:22 <mroman_> lame
18:55:30 <mroman_> I thought it's a hardware translator between those two
18:55:43 <mroman_> like a ARM chip that also supports x86
18:55:53 <mroman_> oh
18:56:03 <olsner> you can get almost that with qemu, I think
18:56:07 <mroman_> that'd be the same as you said :)
18:56:07 <ais523> you could almost do that in microcode
18:56:14 <ais523> we need a customizable-microcode chip, really
18:56:22 <tromp_> my paper at http://homepages.cwi.nl/~tromp/cl/cl.html has an SK self-interpreter
18:56:35 <tromp_> but it's bigger than the lambda calculus self-interpreter
18:56:37 <Jafet> So they've finally given up on drag racing intel
18:57:46 <tromp_> which is under 26 bytes
18:58:24 <nortti> binary lambda calculus?
19:00:06 <tromp_> yep
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19:28:36 <oerjan> FireFly: um how can Zero be both unusable for programming and turing-complete
19:29:33 <FireFly> I thought "unusable for programming" was supposed to be in terms of practicality
19:29:49 <oerjan> in _our_ community?
19:29:59 <FireFly> ...fair point
19:30:08 <FireFly> I'm not sure why I had that idea
19:31:27 <oerjan> although looking at the actual language, i think it's more likely that it's not tc..
19:32:00 <oerjan> by the unusual way of not having any computable reduction from a turing machine to it.
19:32:26 <oerjan> um or the other way, for that matter.
19:33:52 <oerjan> hm actually it _might_ be possible to reduce some universal bf program with input to it.
19:34:35 <oerjan> because the halting sequence will only start being undecidable from some point on, and that point may very well be pretty large
19:36:27 <ais523_> this is like saying "is BF with a source code limit of 200 bytes TC?"
19:36:34 <oerjan> yep
19:36:47 <ais523_> it would be very hard to prove that the answer is no, but if the answer is yes, a proof would likely be trivial
19:39:30 <elliott> ais523_: also you run into L problems
19:40:09 <ais523> err, right
19:40:12 <ais523> curly-L-coplete
19:40:14 <ais523> *complete
19:40:42 <ais523> shachaf: thanks for that Haskell help you gave me a few days ago; how should I credit you in my PhD thesis?
19:40:50 <ais523> atm I credited your nick, but it looks a little unprofessional
19:41:02 <oerjan> Shachaf the Terrible, Lord of all Mankind hth
19:41:55 <fizzie> Sha Chaf is not shachaf's real name?!
19:42:06 <oerjan> afaik it is
19:42:16 <oerjan> well without the space
19:42:33 <oerjan> also he used to have his surname in the /whois but i see it's gone
19:45:23 <fizzie> I went to an IBM recruiting event today, and they made a snide joke at Google's expense.
19:45:31 <oerjan> hm it might actually possible to program in zero entirely, if undecidable points in the halting sequence are sparse enough.
19:46:19 <ais523> oerjan: can you at least force such points to never be an unmatched bracket?
19:46:28 <ais523> if not, the first one is going to mess up your bracket matching
19:46:41 <ais523> also, I have a feeling that Zero may be uncomputable
19:46:59 <oerjan> yeah that's the main problem, you need to have no 3 in a row.
19:47:43 <oerjan> actually 2 in a row is also a problem if they're the first two in a triple
19:48:31 <ais523> "fun" exercise: write a program in Zero that halts if and only if it doesn't halt
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19:48:56 <oerjan> ais523: not sure that's possible to achieve
19:49:02 <ais523> neither am I
19:49:07 <ais523> but if it is, it'd say something about the language
19:49:37 <oerjan> after all the programs tested for the halting sequence are logarithmically shorter than the program you are constructing.
19:50:06 <ais523> you could insert a bunch of NOPs, but even then it'd cause problems
19:50:16 <ais523> because you couldn't reliably make them NOPs
19:50:27 <ais523> like, it'd work if you had "immutable NOPs", Malbolge-style
19:50:37 <ais523> (also programming in Zero would be very easy if you did)
19:50:41 <oerjan> also i think the specification of Zero has some weak points. like the fact that ordinary lexicographic order isn't isomorphic to the natural numbers.
19:51:00 <oerjan> and also, what happens to malformed programs tested in the halting sequence
19:51:02 <fowl> isomorphic is so 90s
19:51:12 <fowl> now we say isographic
19:51:24 * oerjan categorically swats fowl -----###
19:51:28 <fowl> read in the same tone you would read "reaganomics"
19:52:08 <oerjan> also i'm pretty sure Zero is uncomputable if you make no attempt to avoid the undecidable points in the halting sequence.
19:53:02 <oerjan> and come to think about it, avoiding 3 undecidables in a row also seems impossible, even if you can assume malformed programs have an easy value.
19:53:27 <ais523> I imagine the undecidables take quite a while to show up
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19:53:36 <oerjan> yeah
19:53:39 <shachaf> ais523: Hmm, I guess "Shachaf Ben-Kiki" would work.
19:53:45 <shachaf> ais523: Which Haskell help was this?
19:53:56 <oerjan> but i'm thinking of translating general bf programs to it
19:53:57 <ais523> the rank-2 polymorphism declaration
19:54:28 <ais523> I'm trying to give an example of "this program can type with this type in at least one widely used language, but the inference algorithm can't figure it out itself"
19:55:06 <shachaf> Oh, that. OK.
19:56:44 <ais523> perhaps I'll remove the argument altogether because it turned into a bit of a mess
19:57:13 <HackEgo> [wiki] [[Zero]] http://esolangs.org/w/index.php?diff=39466&oldid=39465 * Oerjan * (+18) I'm going to assume you meant this, as the original doesn't give a sequence order
19:57:42 <ais523> shachaf: huh, I thought that name was familiar; I looked at the monitor on my desk, and it has the YAML spec open
19:57:47 <ais523> and one of the authors is Oren Ben-Kiki
19:57:59 <ais523> (and another has a surname of "döt Net")
19:59:36 <ais523> thanks for the help, anyway
19:59:43 <oerjan> ais523: i am thinking that if you could only avoid undecidable brackets in zero (which alas i don't think you can), then all other problems could probably be solved with the ][...] comment trick.
19:59:56 <ais523> oerjan: yes, that would probably work
20:00:16 <ais523> then you could just pad out with 3^n +-+-+-+-
20:00:26 <ais523> and create a paradoxical program
20:00:39 <ais523> that's some level above uncomputable, I think
20:00:56 <ais523> not just "cannot be implemented without an oracle", but "an implementation directly causes a paradox"
20:01:13 <oerjan> um i wasn't thinking of paradoxes here
20:01:23 <oerjan> just general translation to zero
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20:01:48 <ais523> well, if you can translate any BF program to zero in linear time
20:01:51 <ais523> you can produce a paradox
20:01:52 <oerjan> but you are right about the padding, that means you can find equivalent elements further out in the sequence
20:02:33 <shachaf> ais523: Yes.
20:02:39 <shachaf> an ancestor of mine
20:03:20 <ais523> now I'm imagining that the YAML spec is hundreds of years old, which is an awesome mental image
20:04:56 <kmc> hichaf
20:05:46 <fizzie> Is the proper answer "himc", I wonder.
20:05:56 <oerjan> ais523: hm i don't think you can make a paradoxical program in Zero, because the encoding is not self-referential in the right way - the halting sequence tests _unencoded_ programs.
20:06:19 <ais523> oerjan: it doesn't have to test itself for halting
20:06:23 <ais523> just a program that is equivalent to itself
20:06:57 <oerjan> well what i'm saying is Zero programs cannot actually do halting tests once they're up and running.
20:07:57 <oerjan> oh hum on rereading the spec it implies the ordering skips unmatched programs.
20:08:42 <ais523> oerjan: oh, I see; they can test most of themself
20:09:00 <ais523> but they can't test the unsure instruction that they're testing without first knowing what it'll be
20:09:22 <ais523> if we think as a program as a function from the haltingness of a particular other program P to a termination status
20:09:33 <ais523> then P cannot equal the entire /function/, just the application of that function to some argument
20:09:42 <ais523> and that argument has to be defined as a constant, it can't come from a halting oracle
20:10:07 <oerjan> my real argument is that as written, the halting sequence is mathematically well defined, and so therefore is the semantics of a zero program, and so there cannot be any paradox.
20:10:29 <ais523> right
20:10:34 <ais523> I was trying to expose the hole in my argument
20:10:39 <ais523> rather than the hole in yours
20:10:40 <ais523> and I think I found it
20:11:52 <oerjan> fizzie: no the proper response is kmcello hth
20:17:43 <oerjan> hm i'm starting to wonder if you may have enough control of consecutive elements in the halting sequence to at least know whether they give the _same_ bit or not.
20:18:28 <oerjan> like, programs that don't end in brackets will come in groups of 6, all of which must do the same thing.
20:18:36 <oerjan> (afa halting is concerned)
20:19:04 <oerjan> and that is enough to avoid encoding brackets with them
20:23:08 <oerjan> so the trouble happens with programs ending with ]
20:24:40 <oerjan> hm and those can do wild things, like P+] P-] P>] P<] are consequtive in the order.
20:26:13 <oerjan> which is almost certainly enough to encode switching between two independent undecidable subprograms.
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20:54:02 <shachaf> higan
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21:20:26 <kmc> shachaf: I like languages with strong safety guarantees, but I seem to spend a lot of my time learning about ways to break the rules :)
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21:42:14 <john_metcalf> Have any computers other than PDP-11 got a single instruction which copies itself through the entire memory? The PDP-11 instruction is MOV -(PC),-(PC)
21:44:34 <ais523> john_metcalf: you should talk to impomatic about that, pity impomatic isn't online
21:44:51 <ais523> that's a major part of CoreWars strategy, the fact that Redcode has an instruction that does that
21:45:25 <elliott> `addquote <ais523> john_metcalf: you should talk to impomatic about that, pity impomatic isn't online
21:45:26 <HackEgo> 1193) <ais523> john_metcalf: you should talk to impomatic about that, pity impomatic isn't online
21:45:44 <john_metcalf> ais523: same person! jm is my real name :-P
21:45:55 <ais523> elliott: I don't know, it's useful advice, just advice that can't be actd on
21:45:59 <ais523> if not for the reason I expected
21:46:09 <elliott> `revert
21:46:10 <HackEgo> Done.
21:46:17 <ais523> elliott: it's funnier with the context
21:46:26 <oerjan> ain't it always.
21:46:27 <elliott> feel free to readd
21:46:29 <ais523> oh, is that why you reverted, to add the context?
21:47:07 <ais523> hmm
21:47:18 <ais523> most processors don't have PC-relative addressing
21:47:28 <ais523> because compilers typically know where their output is in the program
21:47:36 <fizzie> Is that true?
21:48:02 <fizzie> X86-64 does, ARM does (IIRC).
21:48:14 <kmc> ais523: not with dynamic linking
21:48:15 <elliott> ais523: no, to let others add it if they wish
21:48:28 <john_metcalf> None of the processors I've used allow anything similar to be created.
21:48:54 <kmc> for dynamic linking it's desirable to emit position-independent code, and in that case PC-relative addressing is very useful
21:48:57 <ais523> you might manage it on a processor where the PC is memory-mapped /and/ indirect addressing is supported
21:49:18 <kmc> PIC has a pretty severe performance penalty on 32-bit x86 because of the need to reserve a register for an offset
21:50:41 <ais523> dynamic linking is relatively recent compared to the history of programmers, though, isn't it?
21:50:42 <fizzie> Does it count if you need to set registeres to particular values before the one instruction?
21:51:03 <ais523> fizzie: some sort of movsw instruction?
21:51:11 <kmc> dynamic linking isn't that recent, but there are different implementation strategies and they don't all require PIC
21:51:21 <kmc> http://www.iecc.com/linkers/ has lots on this
21:51:22 <ais523> that's basically *di++ = *si++, if you make di the next line and si the current line
21:51:29 <ais523> then it should keep going until di overflows
21:52:09 <fizzie> I don't see why it'd stop there.
21:52:36 <fizzie> Assuming all address space is mapped and rwx, anyway.
21:54:01 <fizzie> Though a rep stos with the maximum count sounds approximately the same.
21:54:30 <kmc> if a REP MOVSB instruction overwrites itself, the repetition stops after the next processor interrupt
21:54:49 <kmc> which is something emulators tend to implement incorrectly
21:54:50 <kmc> http://repzret.org/p/rep-prefix-and-detecting-valgrind/
21:55:01 <fizzie> But that wasn't a rep.
21:55:18 <fizzie> Interesting, though.
21:55:20 <ais523> kmc: it's not a rep, you're copying the movsb onto the next instruction
21:55:24 <kmc> yeah this is a tangent
21:55:24 <ais523> then executing the new copy
21:55:27 <ais523> imp-style
21:55:27 <kmc> just a bizarre fact
21:55:41 <ais523> also, detecting valgrind is easy
21:55:51 <kmc> because of client requests?
21:55:55 <ais523> yes
21:55:58 <kmc> yeah
21:56:05 <kmc> there really should be a way to disable those, but I didn't find one
21:56:19 <nooodl> kmc: that is cool
21:56:21 <ais523> I remember fixing JPC-RR to do pipeline flushing on self-modifying code
21:56:30 <ais523> it used to just run the old version of the code, and it has a very long pipeline
21:56:32 <kmc> I was wondering if e.g. Native Client code running in Valgrind could use client requests to escape the sandbox
21:56:35 <ais523> I needed to do that so that NetHack would run correctly
21:56:47 <ais523> kmc: there's a client request for "run this on the real CPU", so trivially
21:57:23 <kmc> yeah
21:57:44 <kmc> now how hard is it to set up a NaCl toolchain so i can write a PoC
21:58:13 <ais523> NaCl uses valgrind?
21:58:19 <kmc> no
21:58:27 <kmc> but you can run a NaCl program in Valgrind, like any other program
21:58:29 <ais523> oh, I see
21:58:36 <kmc> and in this case it makes it less secure, not more :)
21:58:46 <ais523> is it still using the prctl-based sandbox? or has it moved to a different sandbox?
21:59:02 <ais523> prctl's basically undefeatable because it limits the syscalls you can use and there's no way to undo it
21:59:28 <ais523> as in, you need to find a kernel bug to get around it no matter how many layers of emulation are used, so long as the emulator runs the prctl call itself
21:59:41 <kmc> no, NaCl is used for sandboxing within a process, aiui
21:59:50 <ais523> oh right
21:59:54 <ais523> I was thinking of a different sandbox entirely
22:00:07 <kmc> I think NaCl in Chrome will run in a process sandbox too
22:00:10 <kmc> but that's separate
22:00:11 <ais523> NaCl's the "run a static analyser on the code to make sure it doesn't try to do anything nasty, then run it unmodified" system
22:00:22 <kmc> NaCl uses a conservative subset of x86 with well behaved static semantics
22:00:28 <john_metcalf> MOVSB imp doesn't work because of the prefetch queue. (Works in a debugger though).
22:00:28 <kmc> plus segmentation
22:00:54 <ais523> john_metcalf: huh, pipeline behaviour causing problems on real processors?
22:01:01 <kmc> I always wondered about memory ordering with self-modifying code
22:01:04 <ais523> what about in 8086 mode?
22:01:24 <kmc> since there's no way to put a read barrier before the other CPU's fetch
22:01:25 <ais523> I know that NetHack overwrites the argument of an int instruction, then runs that instruction immediately afterwards
22:01:42 <ais523> to run arbitrary interrupts
22:02:28 <kmc> why
22:03:00 <john_metcalf> Can't be done on a Z80 without looping. (Demo here) https://www.youtube.com/watch?v=LPqDksPdNiE
22:03:06 <fizzie> How about a "movsd; jmp $+2" one? (Modulo instruction length issues. And not a single instruction.)
22:03:57 <olsner> the manuals do mention self-modifying code with multiple cpus, basically saying "don't do that"
22:03:58 <ais523> I think there might even be room for a NOP in there
22:04:37 <kmc> olsner: fuck tha police
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22:13:10 <olsner> hmm, actually I remembered that wrong, they instead describe some appropriate synchronization procedures for getting cross-modified code to run properly
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22:14:24 <olsner> basically use a memory flag to indicate when your modification is complete, then do cpuid before you jump to any of the modifying code
22:15:22 <ais523> cpuid's a memory barrier?
22:15:25 <ais523> cross-processor?
22:15:29 <ais523> weird instruction to use
22:16:11 <olsner> it's not for memory, I think, but for serializing and emptying pipelines and the whatnots
22:16:32 <ais523> err, instruction cache barrier
22:16:50 <olsner> if it's not cross-cpu doing a jump is enough (but cpuid also works)
22:19:28 <kmc> CPUID is a memory barrier but there are better memory barrier instructions
22:19:44 <kmc> and yeah it's also a barrier to OOE
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22:19:57 <kmc> I don't know which other instructions are
22:20:39 <kmc> some hypervisors virtualize CPUID which makes it very slow for this purpose
22:20:47 <kmc> also, there totally are legitimate use cases for multi-threaded self modifying code
22:22:56 <zzo38> Self modifying codes can be very useful
22:23:56 <zzo38> CPUID isn't a very good idea
22:24:51 <kmc> why not?
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