Is this climbing uphill with Kotlin? Should I just create my own datastructure GameState with getter...

# getting-started

[Georg Ekeberg]

Is this climbing uphill with Kotlin? Should I just create my own datastructure GameState with getters, constructors and setters? Or is there a good way to do this with the inbuilt map structure?

[Stephan Schröder]

mapOf returns a Map-Implementation which doesn't extend from GameState . Your GameState isn't even Map-like, it's Pair-like.
but if all you're looking for is correct typing, why not simply have

fun roll(pinsDown: Int,
         pinsLeft: Int = 10,
         triesLeft: Int = 2): Map<Int,Int> {
    return mapOf( (pinsLeft - pinsDown) to (--triesLeft))
}

to is an generic infix function that returns -in this case- a Pair<Int, Int> (because what you're providing is two Ints).

[Stephan Schröder]

(--triesLeft) might not work though. If I'm not mistaken, then parameters are immutable. (so use (triesLeft-1) instead )

[Georg Ekeberg]

Ok! Thanks, great answers.

[Stephan Schröder]

of course you can also return a GameState but then use the GameState-constructor, not a Map-generating function:

fun roll(pinsDown: Int,
         pinsLeft: Int = 10,
         triesLeft: Int = 2): GameState {
    return GameState(
        pinsLeft = pinsLeft - pinsDown,
        triesLeft = triesLeft-1,
    )
}

that's probably what you want to do. Your approach of creating objects by crating Maps was a step in the wrong direction (do you come from JavaScript? Your approach looks like trying to do dynamic typing in a language that has static typing to me).

[Georg Ekeberg]

Yeah, JS/TS, and a bit of clojure

[Stephan Schröder]

have fun discovering how static types can benefit you (even stricter than in TS). basically you gain security, but mocking gets harder.