Is the bytecode shown by Intellij the final byteco...

# announcements

[deepanshu]

Is the bytecode shown by Intellij the final bytecode produced by the kotlin compiler, or is it optimized further?
As an example, the following code was produced by the Intellij

(0..listA.size - 1).filter{ listA[it] < listB[it] }.forEach { return true}; return false

as a result of intention action to fix "LoopToCallChain` warning on the following loop:

for (i in 0..listA.size - 1) if (listA[i] < listB[i]) return true; return false

The bytecode in the IDE of former snippet shows creation of additional objects, and more importantly, running the comparison for the full list, rather than returning early. Does the compiler at build time optimize it?

[Andreas Sinz]

@deepanshu: your (0..listA.size-1) creates a Range which is an eager Iterator. so running filter { } filters the whole list before running forEach { }. If you want it to be lazily evaluated (returning early) you need to use (0..x).asSequence().filter { }

[Andreas Sinz]

and btw, there is any for Iterables (https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.collections/any.html) which does exactly what you do with filter().forEach(). your code can be written as return (0..listA.size -1).any { listA[it] < listB[it] }

[deepanshu]

Thanks @Andreas Sinz