Having problems with the following code. When I ca...

# getting-started

[Quinn]

Having problems with the following code. When I call .sort { a,b -> distanceFormula } I can no longer access the array named sources. If I don't call sort I have no problems.

var sources = spawn.room.find(FIND_SOURCES).sort { a,b ->
        (a.pos.x - b.pos.x) * (a.pos.x - b.pos.x)
         + (a.pos.y - b.pos.y) * (a.pos.y - b.pos.y)}
    val creepsWithSource1 = creeps.count { it.memory.assignedSource == sources[0].id }
    val creepsWithSource2 = creeps.count { it.memory.assignedSource == sources[1].id }
    val assignedSource = if(creepsWithSource1 < creepsWithSource2) sources[0].id else sources[1].id

This results in the following error message. I'm trying to decipher what this error means so I can understand it in the future.

Unresolved reference. None of the following candidates is applicable because of receiver type mismatch:
public inline operator fun <K, V> Record<Int, [ERROR : No type element]?>.get(key: Int): [ERROR : No type element]? defined in starter

[dalexander]

I believe sort doesn't return the sorted array, but rather sorts it in place. So by calling sort like that you are changing the type of sources. (I ran into a similar problem recently myself)

[Quinn]

Interesting. In that case, I'll play with trying to figure out how to sort this array of sources . Do you happen to know what fun <K, V> is? Is that two types, one of which is Record<Int, [Error]> and the other is .get(key: Int)? I see that the error message mentions that the Record function is returning no type elements. Still very confused by this error messages.

[dalexander]

Ah... the error message isn't very helpful, I agree. The error message is from the code sources[0] ie. you're trying to get the first element in the sources object. And because sort doesn't return a list it's complaining.

[Quinn]

I would not have gleamed that by myself. Thanks @dalexander

[dalexander]

By the way, it is still correct to use sort, but I would do something like:

val sources = spawn.room.find(FIND_SOURCES)
sources.sort { a,b -> (a.pos.x - b.pos.x) * (a.pos.x - b.pos.x) + (a.pos.y - b.pos.y) * (a.pos.y - b.pos.y) }

And no problem, glad I could help 🙂

[Quinn]

Oh I see, that fixed my issue. I was super confused and went to scratch to try to figure it out and was stuck trying to figure out my types lol. Thanks again!

[dalexander]

IDEA has some useful tools for figuring out what type something is. You can check the type of something your cursor is over with ctrl + shift + p on OS X. I think it's similar on Windows. You can also open the "do an action" window with ctrl + shift + a and type in expression type (or any other action, really).

[Quinn]

Will those work outside of debugging? I can't run debugging because this code is for a game called screeps where I am just pushing code to their API.

[Quinn]

I'm converting all of my code to javascript on compile and using types from their API that are converted from javascript to Kotlin. This has made it incredibly difficult to debug.

[dalexander]

The type inference will definitely work outside of debugging.

[dalexander]

types from their API that are converted from javascript to Kotlin I could see this being a problem based on working with loosely typed JS API's in the past.

[dalexander]

This is what invoking type information in the editor looks like

[Quinn]

Ah nice, that is working for me. I just switched from Vim to IntelliJ for kotlin because it's almost completely necessary. Guess IntelliJ has something going for it. Thanks again!