The part about maps is wrong, you can write them like val myMap = mapOf( "A" to 10, "B" to 20 ) etc. Also, regarding that final sente

The part about maps is wrong, you can write them like val myMap = mapOf( "A" to 10, "B" to 20 ) etc. Also, regarding that final sentence about matrices, that sounds like a perfect use case for type aliases.