00:15 <doublec> felko: if the Array[U8] is ref you'll have to copy it

00:15 <doublec> felko: if it's an iso you can recover it to a val without copying

00:16 <felko> how do I copy it ? clone returns a ref

00:17 <doublec> felko: create a new array, and iterate over the old one, pushing items into the new one

00:18 <felko> but push requires the array to be ref

00:18 <felko> doublec: can we use it on an Array val too ?

00:19 <felko> well i could use an iso

00:19 <felko> i think

00:19 <doublec> felko: in general you can work around the copy by using an iso, or by using things inside recover blocks

00:19 <doublec> if the array can be created as a ref inside a recover block, and the population of it done inside of it, then it can be returned from the recover block as a val

00:19 <jemc> felko: if you post a relatively complete snippet, we may be able to help you refactor to use a recover block instead

00:21 <felko> where can i paste a pony snippet with syntax coloring ?

00:22 <felko> http://pastebin.com/AMNw3vFj

00:23 <felko> sorry if this is chaotic, I just started learning pony yesterday

00:23 <doublec> felko: where do you need the val?

00:24 <doublec> felko: is it in the memory() function? You want to return a val?

00:24 <felko> line 35 when I have to provide a Array[U8] val for env.out.print

00:25 <felko> I also put some weird refcaps like String iso! because the compiler seemed to complain about it

00:26 <doublec> That set of lines creates an array, prints it and discards it - is that what you want?

00:27 <felko> yes

00:27 <felko> len = 1 because I haven't found a printChar function for StdStream

00:28 <felko> so i'm just building a 1-character string

00:28 <doublec> felko: let str: Array[U8] val = recover Array[U8].init(5 where len = 1) end

00:29 <felko> thanks

00:29 <felko> sorry all of those refcaps things are really new to me

00:30 <doublec> felko: env.out.print(current().string())

00:30 <doublec> felko: no worries, you're doing well

00:30 <felko> thanks

00:31 <doublec> felko: most types have a .string() that let you convert to something printable

00:31 <felko> ok, i'll remember that, thanks again

00:32 <doublec> 'recover' is a bit like a safe pointer cast. It can convert anything from inside the recover block to another reference capability when it is returned outside of it

00:32 <doublec> It does it safely because the recover block is special in that it restricts what can be put inside it and it knows than nothing can be retained that is created inside it.

00:33 <doublec> as a high level introduction to it

00:34 <doublec> So in that recover block we create an array ref but it is returned as an array val. This is safe because the ref cannot be stored anywhere else as it can't escape the recover block.

00:34 <felko> my experience with pointers is pretty limited, but i think i get the idea

00:35 <doublec> You can go a long way in solving problems by using recover somewhere, or consume something else, to fix compiler errors :)

00:36 <felko> ive been doing this for hours now, fixing error by error

00:36 <felko> not the best way to learn a language I guess :/

00:37 <felko> im starting to understand a little more now, thanks to you

00:37 <doublec> felko: I have some posts here which explain some of it https://bluishcoder.co.nz/tags/pony/

00:38 <felko> wow thanks a lot

00:38 <doublec> in particular the "bang, hat and arrow" one and the "borrowing in pony" one for dealing with and understanding errors

00:39 <felko> last question before i go to bed, is there a way to debug, like, with print, but without having access to the env variable ?

00:39 <felko> i know this is an issue for safety but even haskell does an exception for this

00:40 <doublec> felko: yes, there's a debug print facility

00:40 <felko> thanks

00:41 <doublec> felko: do a: use "debug"

00:41 <doublec> felko: then you can access Debug.out.print, etc

00:41 <felko> found it, thanks

00:41 <doublec> felko: another common approach is to use the C ffi to access printf

00:42 <doublec> felko: so: @printf[None]("I am here: ", mystring.cstring())

00:42 <doublec> felko: actually that's: @printf[None]("I am here: %s".cstring(), mysetring.cstring())

00:42 <doublec> it requires converting types though so is a bit more technical

00:43 <doublec> I have to head out - good luck!

00:43 <felko> thanks a lot, bye :)

21:51 <TwoNotes> Is there a convenient way to invert the "is" test? Like 'if a is not None then...'

21:52 <jemc> TwoNotes: `if not (a is None) then...`

22:09 <Praetonus> TwoNotes: IIRC, there is an `isnt` operator

22:11 <Praetonus> Just checked, it does exist

22:11 <Praetonus> So you can do `if a isnt None then...`

22:16 <TwoNotes> ok, great tnx