07:43 <vaninwagen> hi, quick question. i want to implement a generic method that works for all Int types. i am somehow unable to achieve this. I tried the following: http://playground.ponylang.org/?gist=4d2da0d1159e25ed8d5cdf0a28d3d38d without success

07:44 <vaninwagen> i used the union ``Int`` maybe i should have used the trait Integer but i was unable to get this working too

07:44 <vaninwagen> there must be an easy way

09:39 <vaninwagen> ``fun int_method[T: Integer[T] val](t: T)`` this works \o/

09:39 <vaninwagen> it just can't handle literals

09:42 <vaninwagen> if i use ``t + 1`` the compiler says: main.pony:12:19: could not infer literal type, no valid types found.

09:42 <vaninwagen> does anyone have an idea for a workaround?

10:59 <SeanTAllen> vaninwagen: can you send code that runs into the t+1 issue?

11:27 <vaninwagen> SeanTAllen, yeah sure: http://playground.ponylang.org/?gist=1f6681105506ba286cad3bb272738294

11:38 <vaninwagen> my first guess is that inferring types for literal numeric expressions only works with concrete number types

11:43 <vaninwagen> but i don't understand the code for handling literals ヽ(。_°)ノ

11:43 <SeanTAllen> thats an interesting one

11:44 <vaninwagen> SeanTAllen should i create an issue in ponyc?

11:45 <SeanTAllen> im not sure how to solve it. there could be a way. i'd say sure, go for an issue. other option is email the user list.

11:46 <vaninwagen> whatever you prefer

11:49 <vaninwagen> i already feel guilty for opening that many issues and not getting my few ones done :/

11:51 <SeanTAllen> no need to feel guilty for open issues for things that need to be fixed

11:56 <doublec> vaninwagen: something like this? https://playground.ponylang.org/?gist=1f6681105506ba286cad3bb272738294

11:57 <vaninwagen> doublec this is exactly my example. wrong link?

11:57 <doublec> hmm, not sure why that didn't work

11:58 <doublec> vaninwagen: change to this fun int_shrink[T: (Int & Integer[T] val)](t: T): (T^, Seq[T]) =>

11:58 <doublec> vaninwagen: note the "(Int & Integer[T] val)"

11:58 <vaninwagen> doublec woah!!!

11:59 <doublec> I'd like to take credit but I grepped the pony library sources for Integer[T} usage and found one example that did it.

11:59 <doublec> in format.pony

11:59 <vaninwagen> you have some amazing grep skillz

12:00 <doublec> I live in grep for finding things in the codebases I use haha

12:01 <vaninwagen> so ``Int`` was not working because the concrete types have incompatible signatures, at least thats what the compiler says.

12:01 <vaninwagen> but i don't really get why i got those errors

12:02 <vaninwagen> using ``Integer[T] val`` does not work because literal inference needs the type to be some concrete integer type (and only with Integer[T] val it could be any new class implementing that, which is not handled)

12:03 <vaninwagen> ok, i think i slowly get it :)

12:03 <vaninwagen> thanks for bearing with me

12:04 <vaninwagen> SeanTAllen doublec i'd say not worth an issue. maybe some mark in the tutorial or language reference...

12:04 <doublec> np, I'm not entirely sure why it works myself - it's a good example for discussion

12:04 <doublec> I think it's worth discussing in an issue why it doesn't work

12:04 <doublec> or at least the mailing list

12:39 <SeanTAllen> so what is your final solution vaninwagen?

13:27 <vaninwagen> SeanTAllen, doublecs suggestion worked out fine, using fun int_shrink[T: (Int & Integer[T] val)](t: T): (T^, Seq[T]) =>

13:27 <vaninwagen> i wrote to the user mailing list to ask about the hows and whys

13:29 <SeanTAllen> sounds good

13:51 <fluttershy_> hello, What is position independent code in pony, and when should I use it ? I have a pony binding to a C shared library, is it necessary to use --pic when I include the binding and compile ? SeanTAllen I ve sean you use it when binding to SDL.

13:53 <SeanTAllen> --pic is specific to your OS and libraries fluttershy_

13:53 <SeanTAllen> if your OS/system libraries were compiled with PIC on then anyhting that links against them needs to be PIC

13:56 <fluttershy_> hemmm

13:57 <fluttershy_> well, any gain on performance ?

13:58 <fluttershy_> sorry I am not familiar with the concept position independent code.

13:59 <SeanTAllen> you will lose some performance

13:59 <SeanTAllen> not much but some

13:59 <SeanTAllen> in theory PIC is a security improvement

14:00 <SeanTAllen> https://en.wikipedia.org/wiki/Position-independent_code

14:01 <fluttershy_> hemm, ok ty I will read more about it.

14:02 <SeanTAllen> i wouldnt worry about it beyond-- do i need to compile my application with --pic

14:03 <SeanTAllen> also note if you build the pony compiler from scratch and need to use --pic to compile applications, there is an option when building the compiler to have it turn --pic on my default

14:04 <fluttershy_> yes I read about the issue in the ponylang.org but I was confused about pic. ok then ty.

16:40 <SeanTAllen> i got some info from jemc, vaninwagen, doublec

16:40 <SeanTAllen> I think the issue is that Integer is a trait and thus could have an unbounded set of subtypes theoretically added (outside of stdlib)

16:40 <SeanTAllen> If for some reason you didn't want to use `& Int` another workaround is to use something like this for the literals: `T.from[U8](1)` (edited)

16:40 <SeanTAllen> IIRC, Int is a union type, and only includes types that the compiler has special case knowledge of.

16:40 <SeanTAllen> And the pony compiler doesn't seem to be able to do literal inference for those yet- unknown types

16:41 <SeanTAllen> thats the ^jemc quote

19:01 <vaninwagen> SeanTAllen, jemc that sounds very reasonable, i suspected that

19:01 <vaninwagen> thanks for sharing

19:01 <vaninwagen> but what still puzzles me is why it didnt work with the Int-union type

19:03 <vaninwagen> union says the concrete type will be one of the ones listed, right? but the compiler still complained that: a member of the union type has an incompatible method signature: let min: T = T.min_value()

19:03 <vaninwagen> although the T's min_value() method should return a T^ - so the assignment should be just fine, right?

19:05 <vaninwagen> this assignment should be fine for each possible concrete type (e.g. U8)

19:06 <vaninwagen> sorry, i am surely wrong at some point, just want to know where

19:07 <vaninwagen> btw it is awesome that i can do T.some_constructor() on a type param

19:48 <_etc> I've come across a bit of an awkward case: I have an actor that whose fields rely on a function call that may throw an error. I'd like to either exit the program or do nothing (basically not worry about it) if an error is thrown. So I could make each of these fields have an `| None` in their type in case an error takes place, but this is kind of a

19:48 <_etc> nuisance. Is there any better pattern to handle errors in the construction of actors? (Doesn't show up in classes because the create() function can return an error)

20:08 <vaninwagen> _etc a hacky workaround would be to create an intermediate class containing all the actor constructor arguments as fields and fail there and only create the actor using this class if its creation does not fail

20:12 <_etc> vaninwagen: Yeah that would definitely work

20:13 <_etc> thanks :)

20:14 <SeanTAllen> _etc: https://patterns.ponylang.org/creation/supply-chain.html

20:19 <_etc> Haha that's exactly what I was describing - thanks!

20:46 <vaninwagen> oops, this is actually a valid pattern, and i called it hacky (which it isn't) workaround

23:25 <SeanTAllen> yeah we use it all the time