<< 20-09-2014 >>
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00:49:01Onionhammerdom96 no, I want kqueue! :P
00:49:18dom96implement it then :P
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00:58:23Onionhammerdom96
00:58:30Onionhammeri think it's actually a capitalization issue
00:58:33Onionhammernot an osx issue
00:59:04Onionhammerit's looking for FD_SET, but it's declared as proc fdSet
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01:09:16dom96yes.
01:09:20dom96Just change it and see if it works.
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01:11:38Onionhammerdom96 change 1 thing = fix 5 more things
01:11:42Onionhammeretc etc etc
01:16:18dom96you just need to rename some stuff
01:16:21dom96it's not that hard
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01:31:35Onionhammeryeah, its just time consuming, and time is a limited comodity
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15:01:26wanI've just watched Jonathan Blow talk about his ideas for a new programming language for games: https://www.youtube.com/watch?v=TH9VCN6UkyQ
15:02:13wanHe talks about why he wants something to replace C++, and why (for him, at the moment) D, Go and Rust don't fit the bill yet
15:02:48wanI'm not sure if he encountered Nim yet
15:03:25wan(btw, this is the developer of Braid. He is a famous indie dev)
15:05:33wanNim has a lot of what he's asking for. However, I don't know how we can do joint allocation
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15:24:53dom96wan: Indeed, you should suggest it to him.
15:25:56dom96Why doesn't Rust fit the bill for him?
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15:54:14wanHe feels good about variable ownership, but not the way Rust thinks it. He also feels like Rust might be a 'big idea' language (no unsafe things!) and says that they usually are unproven (unproven benefits: does it have drawbacks?) although he knows that he can unsafe{...} things.
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16:03:05Varriountwan, dom96: But what about threading?
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16:10:20wanI don't remember him talking much about threading. That probably means that he's somewhat content with how to use threads in C/C++, and don't plan on using risky (unproven performance) light thread models
16:10:49Varriountwan: Yes, but Nimrod's threading support is somewhat... restrictive
16:12:12wanIn what way?
16:12:51VarriountYou can't just share objects and data between threads willy-nilly
16:14:10wanWell if there is still threadAnalysis:off, there's a workaround.
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16:57:33flaviu1`_type` isn't a valid identifier :/
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17:56:00AraqVarriount: Nim's threading support is just fine, especially for games
17:56:20Araqwell once I finished the incredibly good fork&join support
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18:08:31Triplefox_Jon blow is unlikely to ever accept garbage collection, he retreats to arguments about top end performance every time the subject comes up. So to sell him on nim would take a carefully constructed argument that would reassure him that collection won't impact him like in other languages
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18:10:45AraqTriplefox_: *shrug*
18:10:59Araqyou can use manual memory management just fine in Nim
18:11:35Triplefox_Yeah, it's just the existence of the stuff tends to be a scare point
18:12:01Triplefox_Especially if it's used throughout libraries
18:14:05Triplefox_If course, c++ already has a similar issue in that library authors will use different subsets
18:15:05Araqbbl
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18:31:09shodan45heh, was going to post that Jonathan Blow video last night, but everyone seemed to be sleeping
18:33:21shodan45I think he made some very good points, but I disagreed on one or 2 fundamental points
18:40:01shodan45games don't always have to have extreme performance, see Minecraft or even his own game Braid
18:40:46Venshodan45: to be fair, the only reason minecraft wasn't rewrote in a lower-level language is that its whole success is based on plugins
18:40:56Triplefox_Yeah, see, that's exactly what he dismisses
18:41:40Triplefox_He tends to get evasive in Twitter arguments when points like that are made
18:43:01shodan45obviously, some games (or heck, any kind of application) do push boundaries of what's possible
18:45:12shodan45but in that case, wouldn't a good programmer use hacks to increase performance in any language?
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18:46:04Trixar_zaWith me that's more habit than personal pride
18:50:31shodan45Nimrod does seem like a pretty good fit for what he's describing, though
18:56:25shodan45I haven't been keeping up with nimrod for the last ~2 months... what have I missed?
18:56:51shodan45I saw something about changing the name to just "nim"
18:57:30Triplefox_Yeah, that is the new name
18:57:35shodan45and something about changing to case-sensitive
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18:58:29Trixar_zawait - what?
19:09:32bogenpartially case sensitve
19:09:49bogenbut that will be able to be disabled as far as I know
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19:56:17Mat3hello
19:57:15dom96hi
20:02:05Mat3hi dom96
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20:25:07Onionhammerheh, in that talk he does want "compile time functions in the same language"
20:25:09Onionhammer:)
20:25:29shodan45Onionhammer: yep!
20:26:04shodan45quite a few things he said made me yell "nimrod" at the screen ;)
20:26:42shodan45it was surprisingly good for being so long
20:27:07shodan45although it was more or less over at 90 minutes in
20:30:32Jehan_What talk are you guys talking about?
20:31:01shodan45Jehan_: https://www.youtube.com/watch?v=TH9VCN6UkyQ
20:31:28Jehan_Ah, Jonathan Blow's. Yeah, I watched it.
20:31:57Jehan_I was happy to finally hear someone else say that RAII is not actually a good idea.
20:33:12Mat3sorry, what_s RAII ?
20:33:40Jehan_Mat3: http://en.wikipedia.org/wiki/Resource_Acquisition_Is_Initialization
20:34:03Triplefox_It's a nice pattern for the things it solves
20:34:05Jehan_I'd describe the issues differently, though.
20:34:15Triplefox_Which i agree aren't that big for games
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20:35:21Jehan_In my opinion, the presence of RAII is generally evidence that the language lacks automatic memory management and higher-order functions. RAII is also fundamentally at odds with concurrency except for simple cases.
20:36:26Jehan_Even if you can't do automatic memory management (as he says), RAII is a bad choice for a poor man's garbage collector.
20:38:25Jehan_Even if you want to do basic reference counting for memory counting, at the very least you need compiler support if you don't want either (1) huge runtime overhead or (2) blow up the code footprint (what he's talking about in the video, also known as the Rule of Three (which should by now be the Rule of Five)).
20:39:22Triplefox_I feel like a lot of what the folks looking for precise control need are "lifetime patterns" built in the language... terse ways to describe the strategy they're using
20:39:51Jehan_Triplefox_: That's what higher order functions are for.
20:40:59Triplefox_Well, that's a general construct that does it, but if you're using the same handful of patterns in the code...
20:42:03EXetoCbut isn't RAII used for semantics too?
20:42:34shodan45sorta like python's "with" statement
20:42:51shodan45(don't remember if nimrod has that)
20:43:13EXetoCexcept then it might not exactly be RAII
20:44:08Jehan_shodan45: There's no need for a separate with statement if your language has proper support for higher order functions.
20:45:07Jehan_shodan45: You can write the with statement in Nim as a procedure or template, for example.
20:45:37Jehan_Smalltalk never had a with statement, because blocks are a key element of the language, so it was never necessary.
20:45:50Triplefox_I don't disagree that the semantics of higher order are helpful, i just think that people coming in anew want to be pointed to a standard library of them
20:46:08shodan45sure.... "with" isn't strictly necessary in python, either
20:48:23Jehan_Triplefox_: Yeah, but the same holds for RAII.
20:48:40Jehan_shodan45: The issue in Python is that it doesn't allow for closures that are inline statements.
20:49:02Jehan_You can do closures that are expressions, and you can do closures that are explicit defs.
20:49:28shodan45python doesn't do many things.... some would say that's a good thing ;)
20:49:56Jehan_shodan45: The problem here is not that it doesn't do them, it's that what it does is incomplete.
20:50:16Jehan_The functionality is already there with `lambda`, it's just that `lambda` is too limited.
20:50:51Jehan_And as a result, Python actually got MORE features (with statements, and arguably iterators).
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20:51:29Jehan_I note that iterators are not equivalent to closures (since you need continuations to implement them fully), but they have a lot of overlapping use cases.
20:51:53Mat3well, /me thinks tacit programming is an universal solution by design to the problem RAII adresses as extension
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21:47:27Araqbogen: --cs:partial is effectively not an option
21:47:55Araqlibraries can and will export both Foo and foo and then you have no choice but to enable it
21:48:27Araqhowever ... I'm playing with better symbol disambiguation
21:48:49Araqso that --cs:partial won't be necessary to support what people want
21:50:00Araqbut I'm also not a fan of "the compiler resolves it completely different than the ordinary programmer"
21:50:20Jehan_I think the biggest problem is that in Nim's syntax type names can occur in the same places that other identifiers do.
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21:50:59Jehan_That's a convenience feature (so you can write int(foo)), but it means you need a way to disambiguate between types and variables/procedures/templates.
21:51:28AraqJehan_: it's however also essential for a macro system
21:51:33Jehan_Araq: Yeah.
21:52:16Araqwe could require type.Foo for "type context following"
21:52:20Jehan_Iv'e been wondering if it could be possible to have types and non-types of the same name and have a different mechanism to disambiguate between them.
21:52:39Jehan_If it can't be deduced from the context, with a specific annotation.
21:52:44Araqyeah and it's quite easy to do
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21:53:10Araqbut I don't think it's acceptable
21:53:23AraqinitTable[type.int]()
21:53:28Araqvs
21:53:33AraqinitTable[int]()
21:54:02Jehan_Well, the idea would be to only use the explicit annotation where the compiler can't infer which is which.
21:54:17Araqok that can work
21:54:50Jehan_I have no idea how much that would complicate the implementation, though.
21:55:23Araqwell not that much
21:55:46AraqI need to go through the code anyway to fix some nasty corner case bugs
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21:57:21Araqbut as I said, it seems bad that the programmer looks at the case of the first char to determine what is meant
21:57:30Araqand the compiler does something very different
21:57:43Araqand might come to the same conclusions
21:57:58Araqalmost always unless it doesn't
21:58:26Araqand then you have to write type.Foo
21:59:30Araqit's hard to justify such a design, isn't it?
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22:00:15Jehan_Hmm, if I try to actually use type.int(x), then the compiler segfaults.
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22:00:45Araqok that's a bug of course
22:00:59Araqbut type.Foo is only the suggested syntax
22:01:04Araqit's not been implemented
22:01:05Jehan_Yeah, wasn't a complaint. I just thought I should mention it.
22:01:11Araqsure
22:01:12Jehan_Gotcha.
22:01:22Jehan_I thought it was an existing feature that I had been unaware of.
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22:07:50ehaliewiczare blocks lexically bound inside closures?
22:08:22ehaliewiczfor example, if i declare a block, and inside that block create a closure that breaks from that block
22:08:34ehaliewicznvm that doesn't make sense
22:08:56ehaliewiczmaybe it makes sense as long as the closure doesn't leave that scope :)
22:10:00ehaliewiczdoesn't look like it works
22:10:15Araqclosures cannot 'break' outer loops
22:10:26ehaliewiczah, ok
22:10:32ehaliewiczi don't know if there's much use when you have exceptions
22:10:34ehaliewiczjust curious
22:10:35Araqit's also not necessary, you can use a template instead
22:11:32ehaliewiczwell i was thinking more of a continuation sort of thing
22:11:40ehaliewiczbut again, exceptions are probably what i'm looking for
22:11:40Araqin fact, that fine grained interaction with control flow is the most important reason why templates even exist
22:13:13AraqJehan_: btw I'm implementing a 'guard' annotation
22:13:25Jehan_Araq: which does what?
22:13:32Araqvar foo {.guard: LockL.}: int
22:13:40Araqecho foo # invalid
22:13:49Araqlock LockL: echo foo # valid
22:14:21Araqwell
22:14:36Araqtop level accesses are assumed to be constructions
22:14:42Araqso are not prevented
22:15:27Araqit's all very easy to implement
22:15:44Araqand as you said, equivalent to the 'not nil' checking
22:15:55Jehan_Checked at compile time or runtime?
22:16:03Araqcompile-time
22:16:33Jehan_I take it that you can't use that for heap-allocated data, then?
22:17:40Araqsurely you can
22:17:55Araqthe annotation then belongs to a field of an object
22:18:04Araqtype Foo = object
22:18:18Araq i [.guard: L.}: int
22:18:24Araq L: Lock
22:18:32Jehan_Oh, I see.
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22:19:04Araqthat replaces the idea of a 'guarded ptr'
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22:19:29Araqit's so simple to implement that I decided to do it for 0.9.6
22:19:32Jehan_Are you requiring a specific implementation for locks or just one that conforms to a certain type signature?
22:20:02Araqnot even that, it doesn't require any particular type
22:20:14Araqthere is some other pragma that works like this:
22:20:21Jehan_Also, does it purely allow for mutexes or read-write locks also at this point?
22:20:39Jehan_Hmm, if it doesn't require anything, how do you check it?
22:20:48Araq {.locks: [c.L].}:
22:20:49Araq inc c.i
22:21:06Araqwhere c is of the Foo type defined above
22:21:15Jehan_I see.
22:21:23Araqthe trick is that the .locks pragma shouldn not be used directly
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22:21:35Araqbut it's used all various kinds of lock templates
22:21:45Jehan_That's a pretty general mechanism and probably also useful for other use cases.
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22:22:08Araqyeah, I love it
22:22:21Araqit's simple, general and thus powerful
22:25:08Araqin contrast the deadlock prevention requires some builtin notion of the Lock[Locklevel] type
22:25:15Araqthe idea of valid lock nestings
22:25:24Araqand some addition to the effect system
22:25:58Araqso I don't think it'll make it into 1.0
22:26:24Jehan_Deadlock prevention is tricky.
22:26:41Jehan_There's a spectrum of possible solutions and each of them has drawbacks.
22:26:45Demosdeadlocks are some of the more obvious threading errors though, which is nice
22:27:18Jehan_At the one extreme you get the case where it's too strict and gets into your way of writing code, at the other extreme it's too permissive and you have a hard time testing for bugs.
22:27:44AraqJehan_: now I think the most common deadlock is due to a condition variable where the condition never holds
22:28:00Araqwhich my deadlock prevention design doesn't address at all
22:28:11Jehan_I designed a system to eliminate deadlocks in my Ph.D. thesis, but the problem was that it left a pretty huge footprint on the language and (to a lesser degree) on the modules involved.
22:28:25Jehan_Araq: Yes, system level vs. application level deadlock.
22:28:37Jehan_You can't really solve the latter without solving the halting problem.
22:28:46Jehan_What you CAN do is provide means to recover from it.
22:29:19Araqwhat we *could* do for version 1.0 is to warn when lock statements are nested
22:29:39Araqperhaps in some subtle fashion
22:29:42Jehan_That said, you'd be surprised how often nested locking can bite you.
22:30:09Jehan_At the same time, sometimes you need some form of nested locking that's not amenable to a simple deadlock prevention algorithm.
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22:30:40Araqhi Samson__ welcome
22:31:14Araqyeah well in general I have simpler use cases than you in mind, I think
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22:31:50Araqbut I've done some analysis in a big system
22:32:17Araqand ended up to avoid nesting and instead recompute parts of the algorithm instead
22:32:29Araqto ensure deadlock freedom
22:32:33Jehan_Araq: As long as you have an escape mechanism, you're generally going to be fine.
22:32:50AraqI had no escape mechanism
22:33:09AraqI also had no multi-lock statement
22:33:16Jehan_Most recently, I simply implemented a hierarchy and allowed programmers to have locks that ignored the hierarchy.
22:33:26Araqinstead I rewrote the algorithm
22:40:30AraqJehan_: what do you think about a define that simply injects the lock implementation with a global timeout?
22:41:46Jehan_Araq: A timeout won't really help you, because the typical implementation is "while not foo: wait(condvar, mutex)"
22:42:19Jehan_Unless you let the timeout raise an exception, which can be dangerous.
22:42:42Araqyeah but that's what I had in mind
22:42:54Araqacquire essential is then tryAcquire
22:43:01Araq*essentially
22:43:29Jehan_If you do that, you need a mechanism to clean up locks that are still being held.
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22:43:40Jehan_Or you'll just amplify your problems.
22:44:13Jehan_Concurrent code running into undefined behavior is a really sticky issue.
22:44:22Araqwell the release should really be in a 'finally' anyway?
22:44:48Jehan_Ideally, you shouldn't work with mutexes and condvars directly, but only through higher level abstractions.
22:45:02Jehan_Araq: Not all uses of locks are scoped. They often cannot be.
22:46:24Jehan_Which keeps bringing me back to that one design I have in mind that would not only resolve this issue but also make deadlocks impossible. I'm not sure if the costs are worth it.
22:47:02Jehan_It basically comes down to any blocking or potentially blocking operation releasing all currently held locks.
22:47:32Jehan_And yes, you can design language features so that this is reasonably safe.
22:49:05Jehan_Essentially, when you're trying to acquire a new lock, you (conceptually, optimizers can often avoid this) first release all acquired locks, then reacquire them as one single multilock statement.
22:49:25Jehan_Any blocking operation temporarily releases all held locks, then reacquires them atomically.
22:49:47Jehan_The tricky part is that it's hard to write abstractions over this.
22:50:12Jehan_You need to basically annotate functions to say "this function may spontaneously allow other threads access to shared state".
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22:50:42Jehan_Which raises some ugly composability issues.
22:51:09Jehan_They can be sidestepped through other mechanisms, but never fully eliminated.
22:52:39Araqinteresting
22:53:01Araqthis is what the first deadlock avoidance mechanism did
22:53:08Araqthat I implemented for nim
22:53:14Araqbut I'm sure you remember
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22:59:55AraqJehan_: one problem that I have with "this is overly restrictive, I know there can be no deadlock here" line of reasoning is that really in general you don't
23:00:23Jehan_Araq: By that I mean that you can't have system level deadlock.
23:00:26Araqyou think you do know better and that you don't need hierarchical locking
23:00:31Jehan_And you can break application level deadlock safely.
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23:00:56Araqbut if you can't do it in a formal way that the type system requires you to do
23:01:11Araqyou often really got it wrong in a subtle way
23:01:28Jehan_Araq: Not sure what you mean?
23:02:01AraqI mean if we do the lock level implementation as I suggested in my blog post
23:02:16Araqthen there will be lots of cases where it's simply annoying
23:02:23Araqand overly restrictive
23:02:43Araqbut I don't know if/how exactly you know for sure what you did is safe
23:03:24Araqif you don't follow the rules that the formal lock level system implies
23:05:08Jehan_Okay, now I understand. I thought you were talking about my half-baked idea.
23:05:25Jehan_But yeah, you're right. This stuff is hard to understand.
23:06:04Jehan_At the same time, if you need to, you CAN specify formal invariants to show that deadlocks can't occur in systems where a simple nesting-based scheme can't decide that.
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23:08:38AraqJehan_: yeah sure but I claim these are
23:08:42Araq(a) rare
23:08:51Jehan_Yes, they are.
23:09:02Araq(b) not really stable once you consider refactoring in the real world
23:09:17Jehan_Which is why I think a simple way of deadlock prevention with an escape hatch is a good compromise.
23:09:26Araq(c) circumventable via 'cast' just like everything else
23:09:35Jehan_With the understanding that the escape hatch is to be used rarely.
23:09:49Jehan_As I said, that's pretty much what I went for.
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23:28:56AraqJehan_: ok, but what does that mean? lock levels should be done eventually? or is the deadlock avoidance at runtime preferable?
23:29:41Jehan_Araq: I don't think there's a "best" implementation there.
23:30:00Jehan_If you have a hierarchy of lock levels that is too limited, you CAN run into problems.
23:30:11starlessJesus Christ. implicit return values? why??
23:30:18starlessme and nimrod were getting on so well
23:30:39Jehan_starless: What do you mean by "implicit return values"?
23:31:06starlessproc boo(): bool =
23:31:09starless discard
23:31:11starlessreturns false
23:31:13starlessno error
23:31:52Jehan_Ah, I see.
23:32:25starlessI have never been so shocked. Nimrod is so well designed.
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23:32:54Jehan_The implicit "result" variable is an Eiffel/Pascal concept. It has its advantages and disadvantages.
23:33:34Jehan_Eiffel has it because Eiffel is pretty strict about control flow. There's no goto, break, continue in Eiffel, and thus, also no return.
23:33:56Jehan_In other Pascal-like languages, it's discourage also.
23:34:16Jehan_So, there needs to be a different way to return the value.
23:34:53Jehan_The real "problem", though, is that you can use a variable without having initialized it explicitly.
23:35:09Triplefox_i tend to use "result" as my return variable everywhere after using Pascal for a while :D
23:35:10Jehan_This, again, has advantages and disadvantages.
23:35:28Jehan_Triplefox_: Yeah, my C code usually has a result variable and returns it at the end.
23:36:47starlessSo what are the advantages?
23:36:54starlessThe disadvantages are glaring at me right now.
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23:40:29Jehan_One disadvantage of requiring explicit initialization is that it requires flow control analysis, which complicates the language in other ways.
23:41:15Jehan_For example: if condition: result = … else: signalError() # raises an exception is safe, but the compiler can't tell.
23:42:24Jehan_You could require that you always initialize result before branching, but then programmers would just stick the default value in, anyway.
23:42:40Jehan_Which buys you nothing but wastes vertical screen real estate.
23:45:45starlessI guess I'd have to be a language designer to understand.
23:46:25Araqstarless: there is a way to activate what you want, but iirc not for 'result'
23:47:02Araqcan you gist me your real world example how the features bite you?
23:47:29Araqcause IME the disadvantages are obvious, but also irrelevant
23:48:41Jehan_Oh, I forgot another reason why Eiffel has a result variable (somewhat tangential), and that is to be able to express postconditions involving the return value.
23:48:46starlessAraq: anytime I reach the end of a procedure without returning a value I get a default value for the data type
23:49:16Araqstarless: yes and it's an idiom
23:49:30AraqI use it everywhere
23:49:45Jehan_starless: I think what he's asking if that this is actually likely to result in a software defect.
23:50:13starlessOkay, so I was making a text adventure game to toy with the language
23:50:18Jehan_Which I personally wouldn't know, one way or another.
23:50:22starlessI prompted the user if they were a boy or a girl
23:50:29starlesscase of "yes"...of "no"
23:50:37starlessI put "y" when I tested
23:50:41starlessand it told me I was a girl
23:50:47starless(sorry, it asks if you are male)
23:51:12starlessit's silly but I see that spiraling into bigger bugs
23:51:16starlessmaybe it's just my imagination
23:51:52Jehan_I think the culprit here is that case for strings does not require an else clause as for other types.
23:52:28starlesswhich I also disagreed with but it was marginally forgivable in the sense that you'd always have to give an "else" clause
23:52:42starlessin retrospect perhaps it's not a good idea to make that "else" clause optional
23:53:55Araqyeah
23:54:13Araqmany people complained about that for string cases
23:54:25AraqI can change that for bigbreak
23:55:02ehaliewiczjust curious, are exceptions implemented via setjmp/longjmp in the c backend?
23:55:05starlessbigbreak?
23:56:00Jehan_ehaliewicz: Yes.
23:57:30Jehan_Speaking of which, I see that it uses setjmp() over _setjmp() or sigsetjmp().
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23:58:07starlessAraq: ping
23:58:12starlessreally curious
23:58:18Jehan_That's probably not a good idea (setjmp() saves the procmask, which is considerable overhead).
23:58:35Jehan_starless: bigbreak is the "breaking changes" branch.
23:59:19starlessah. okay. don't forget the on-site tutorial, then. it mentions strings not needed a default case.
23:59:37starlessand thanks then, for your consideration, Araq.
23:59:53starlessneeding*