Collections
Always prefer read-only view collections over mutable ones. Since read-only view collections can't be changed, you can prevent a lot of bugs that relate to multithreading and state inconsistency. If you need to iterate elements of an ArrayList, consider the while loop:
inline fun <reified T> List<T>.foreach(crossinline invoke: (T) -> Unit): Unit {
val size = size
var i = 0
while (i < size) {
invoke(get(i))
i ++
}
}
Sequences can improve performance significantly, especially if you use methods such as first:
@Benchmark
fun sequence() = (0..1_000_000)
.asSequence()
.filter { it % 2 == 0 }
.map { it * it }
.first()
