I can use the following as a way to generate a 10x...

# getting-started

[Ray Rahke]

I can use the following as a way to generate a 10x10 2d grid in a nice 1liner

fun main() {
    val grid: List<List<Boolean>> = List(size=10) { List(size=10) { false }}
}

However this does not seem supported for mutable lists

fun main() {
    val grid: MutableList<MutableList<Boolean>> = MutableList(size=10) { MutableList(size=10) { false }}
}

Why?

And is there an analogous way to build this grid in 1 single readable expression?

[CLOVIS]

What is the use-case? Why do you want a matrix that can change size? You will have no guarantees that all rows are the same length.

[Javier]

https://github.com/Kotlin/multik

[Ray Rahke]

The inner grid is all that needs to be mutatable technically

[Ray Rahke]

it is for conway's game of life

[Ray Rahke]

so the inner needs to be hcangable

[Ray Rahke]

a cell can change from true to false

[CLOVIS]

You probably should have a List<List<Cell>> where Cell is a mutable class, to avoid rows changing sizes.

[CLOVIS]

Or keep List<List<Boolean>> and copy the matrix each time, if you want time travel.

[Sam]

However this does not seem supported for mutable lists

What makes you say that? The code you posted in your question works fine for me...

[CLOVIS]

But honestly, the best solution would be to use multik

[Sam]

Anyway I think I'd go with

List(10) { BooleanArray(10) }

Then you get mutable cells without being able to accidentally change the size 👍

[Ray Rahke]

Oh I guess the code does work. Sworn I remmeber it not earlier

[ephemient]

a quadtree is a better representation for GoL anyway, extends to hashlife