A modern programming language that makes developers happier.

kotlinlang

<https://todd.ginsberg.com/post/advent-of-code/2019/day1/>

I went with a recursive solution to Part 2. I never use recursion it seems, unless I'm writing AoC solutions. :slightly_smiling_face:

Nice! Recursion is definitely an AoC-only topic for me :smile: I seem to struggle more to intuit the behavior of a recursive function where a value is accumulated by passing it down through args as you did here.

I experimented with inline classes today and found them a bit more awkward than I was hoping: <https://github.com/stkent/AdventOfCode2019/blob/master/day01/src/main/kotlin/Main.kt>

Good opportunity to break out `coerceAtLeast` tho!

Oh I didn't know about `coerceAtLeast`! That's cool.

Yeah, I wish inline classes were a bit more useful. I like how they implemented unsigned ints with them, but I feel like unless I can validate the underlying they would be more useful.

Why not use the return as the carry?
```private fun Int.fuelWithFuel(): Int =
        if (this &lt; 7) {
            0
        } else {
            val fuel = this / 3 - 2
            fuel + fuel.fuelWithFuel()
        }```

(this isn't tail recursive any more but you weren't using that anyway)

Also used recursion to finish part 2. But I already have used recursion in production project (yeah it's possible :p). Mostly for iterate over sub folders or tree hierarchy.

Nice! I like recursion, but my work (back end for a financial services company) doesn't really call for it unfortunately. I DO get to write Kotlin though, so there's that. :smile:

Yeah, Karel, that's a really great point. I didn't really need the carry I guess. Good call.

Thanks again <@U5UU34LPK> - I published an update and credited you. :slightly_smiling_face:

Best part of this channel is seeing all this learning/tweaking!

Yeah, exactly. I learn something every day.

I used a `fold` for the first part, and a `do...while` loop for the second. I can't help but think there's a more... kotlin-y solution?

You can force something with `generateSequence` but I couldn't find anything that was actually better.