07:01 <triangle345> hey is anyone here

07:02 <triangle345> i have a question regarding capabilities having some minor confusion

07:03 <triangle345> I'm passing an Array[U8] to a c ffi via cponiter(). This ffi is populating the array and when i return from the c ffi , I try to print the contents using String.from_array but it is empty? Do i have the capabilities mixed up or something. I can see it being populated on the c side

14:34 <SeanTAllen> triangle345: capabilities wouldn't impact on that.

14:35 <SeanTAllen> in order to help, we'd need a small, self contained (preferably runnable) example that demonstrates the problem

14:43 <anqur> Hi, I'm reading libponyrt src to learn some gc and asio. I have a doubt that why the stdfd functions like pony_os_std_print still use fprintf without multiplexing, won't it be blocking? And why asio seems only to be used in sockfd? Am I right about them, for maybe I missed some details?

15:05 <triangle345> no problem

15:05 <triangle345> let me post something on pastebin

15:07 <triangle345> http://pastebin.com/gMEedqsS

15:36 <SeanTAllen> anqur: re the first, can you highlight a specific concern related to specific code?

15:37 <SeanTAllen> anqur: asio is used in a variety of places, tcp, udp, timers, process monitor, stdin, signals

15:39 <SeanTAllen> @triangle345 there isn't enough code there to stay anything. its not at all clear what pony_win_proc_read is doing or that it is being used correctly

15:45 <triangle345> you substitute that call for windows @ReadFile: https://msdn.microsoft.com/en-us/library/windows/desktop/aa365467(v=vs.85).aspx

15:45 <triangle345> it does the same thing

15:46 <anqur> SeanTAllen: https://github.com/ponylang/ponyc/blob/master/src/libponyrt/lang/stdfd.c#L510 I'm concerned about the stdfd writing like stdout but I noticed that it was simply fprintf. I'm curious about what are the original design ideas about writing something to stdout?

16:06 <SeanTAllen> what specficially is your concern anqur?

16:07 <SeanTAllen> triangle345: are you saying that @pony_win_proc_read is purely a wrapper for that call?

16:12 <triangle345> yes

16:13 <triangle345> sometimes i even substitute for it. i just created the wrapper to further debug why the array isnt being populated.. even when I put stuff in the array manually I see nothing come out of the other side

16:14 <anqur> SeanTAllen: I'm...well, learning how to create a lightweight message-passing framework and tryna get to know Pony's epoll mechanism for some uses like socket, signals and files (files I realized that it is cffi). So I'm kinda confused how to multiplex the use of stdout or other stdfds in Pony and think further about my design. So I said that I was curious

16:14 <anqur> about how Pony manipulates stdio.

16:31 <SeanTAllen> anqur: env.out is an actor. so, if stdout where to block, it would only block that one actor. you could make it event driven but i'm not sure you would get much from that. if you had an actor that was responsible for read and write, that would be a more interesting use case.

16:32 <SeanTAllen> can you clarify what you mean by "multiplex the use of stdout", to make sure my interpretation matches your intended meaning?

16:33 <SeanTAllen> triangle345: without seeing actual code, i can't comment on your problem. i don't see how your Pointer[None] for example in the code you supplied matches up with what you say you are wrapping

16:38 <anqur> SeanTAllen: oh yes I thought you just matched what I basically meant. I used to think that an asio instance is manipulated by different schedulers to write different data to stdout (I meant this "multiplexing" maybe I'm wrong...). And you just indicated that in fact stdio is in the control of one single actor (env) which I totally missed this, sorry. I

16:38 <anqur> thought I now understood how to further my design now. :)

16:42 <SeanTAllen> ah ok. good.

19:16 <triangle345> hey Sean is there a simple way of passing an array to a function , modifing/adding data to that array within the function, and printing the result in the parent function?

19:16 <triangle345> I notice that you can create an array as an iso but you have to consume it all the way in the function, which cannot be accessed after teh function returns

19:17 <triangle345> and you cant use ref array because print is a behavior

19:19 <SeanTAllen> so, once you print this out, will you want to use the array some more triangle345 ?

19:19 <SeanTAllen> and by use, i mean modify, update etc?

19:20 <triangle345> possibly

19:20 <triangle345> lets take the case that i wont

19:21 <SeanTAllen> if you need to modify it further then you need to create a copy to print

19:21 <SeanTAllen> if you dont need to modify it later, you want a `trn`

19:21 <triangle345> i see

19:21 <SeanTAllen> you can treat it like a ref and modify it

19:21 <SeanTAllen> then when you consume it, you have a val that can be shared

19:44 <triangle345> hmm when passing my trn array to the function im getting an error like so Array[U8 val] trn! is not a subtype of Array[U8 val] trn: trn! is not a subtype of trn

19:44 <triangle345> my function is like so: fun mytest(dat:Array[U8] trn) =>

19:45 <triangle345> i thought that should be ok? error seems a bit ambiguous as I am passing trn

20:10 <doublec> triangle345: it's because you are aliasing the trn

20:10 <doublec> triangle345: the ! means it is being aliased

20:11 <doublec> triangle345: see here for a write up I did https://bluishcoder.co.nz/2016/05/04/bang-hat-and-arrow-in-pony.html

20:36 <triangle345> thank you

20:42 <doublec> triangle345: I don't see anything obviously wrong with your ffi code

20:43 <doublec> triangle345: unless cpointer() does a copy somewhere but it doesn't look like it

22:01 <triangle345> figured out the issue.. the array has to be Array[U8].>undefined

22:01 <triangle345> what does "undefined" do?

22:03 <SeanTAllen> it initialzes the array to the given size

22:03 <SeanTAllen> using "undefined" data

22:04 <SeanTAllen> as compared to `init` that will initialize every entry to a given value

22:38 <triangle345> i see