03:26 <svenskunganka> Hi! I've decided to try to learn pony, and started reading the tutorial for three hours ago or so. My project for learning new languages is always to build a filetype matching library that matches by magic numbers. However I'm not sure what the pony way is to do multiple expressions in a single if. This is what I got so far: https://playground.ponylang.org/?gist=88314b25eb154bcf45b7240e39abf5d5

03:26 <svenskunganka> I want to check an arbitrary-sized Array[U8] at specific indices for a value

04:14 <vaninwagen> Looks good, you can combine multiple if conditions with and and or

04:16 <vaninwagen> For your use case it might be interesting to use buffered.Reader to read your magic Numbers as integer values from a byte array https://stdlib.ponylang.org/buffered-Reader/

04:36 <svenskunganka> That looks more like what I need. I understand that I can have multiple conditions inside an if, but the precedence thing would make the code quite unreadable.

04:38 <vaninwagen> You can wrap the condition over multiple lines, if that helps

04:38 <vaninwagen> The precedence thing might seem strange at first but it saved my ass more than once already

04:40 <svenskunganka> How'd that look like? I tried breaking it into multiple lines but I got the "syntax error: unterminated if expression"

04:45 <svenskunganka> brb, gonna buy some breakfast

04:47 <vaninwagen> You need to put the single comparisons in parens, otherwise they might be mixed up with the and operators. Also dont forget the 'then' at the end of your if condition.

04:48 <vaninwagen> I am at the phone right now, and the playground is pretty much unusable here, i will post an example later

05:25 <svenskunganka> I see, that makes sense. Thanks for your pointers, I'll try my way forward and see how I can apply them. The goal is to have an API where you do something like this: https://gist.github.com/Svenskunganka/c7dc715ded00704205b30bb4869d58fd

05:25 <svenskunganka> Does that look like "idiomatic" pony or is there something I'm misunderstanding from the tutorial?

05:43 <vaninwagen> That makes very much sense, looks nice

05:45 <svenskunganka> That is awesome, Pony seems like a really nice language so far!

12:01 <svenskunganka> Is it possible to reopen a type alias across packages? Say I have

12:01 <svenskunganka> type Audio is (Mp3 | Midi)

12:01 <svenskunganka> In a package

12:02 <svenskunganka> Is it possible to add another to that alias from another package/main program? E.g

12:02 <svenskunganka> type Audio is Ogg then becomes type Audio is (Mp3 | Midi | Ogg)

12:04 <vaninwagen> No, that is not possible

12:04 <vaninwagen> But what you describe looks like you want to use a trait or Interface for that

12:06 <svenskunganka> I thought those only were able to be applied to classes?

12:40 <vaninwagen> They are applicable to everything, classes, actors, primitives, object literals...

12:50 <SeanTAllen> vaninwagen: why are you thinking svenskunganka wants a trait?

13:32 <vaninwagen> A trait or interface Instead of a union if he wants it to be extendable. A union is a closed type

13:34 <vaninwagen> If he wants something that includes all possible values that can be Audio e.g.

13:38 <svenskunganka> I got it to work with traits! Should be extendable: https://playground.ponylang.org/?gist=78f09c1d10ba636e54254cae728a3528

13:39 <svenskunganka> So users of the library can add their own matchers and categorize them with `primitive Wow is (Audio & FiletypeMatcher)`

13:39 <svenskunganka> If `Wow` were an audio filetype

13:43 <svenskunganka> Now I've got a lot of tidying up and looking over the capabilities