Also asking here hoping to understand that part

kotlinc

is the compiler. So you're going to compile Kotlin sourcecode to be run on a JVM. (There's Kotlin native, JS and so on but without script option) The script option still compile it, I think. Last time I checked, I used kscript to write Kotlin script and there is some overhead when running a script (compilation), however it kscript can also cache the compiled code. Resources: The KEEP: https://github.com/Kotlin/KEEP/blob/master/proposals/scripting-support.md Kscript: https://github.com/holgerbrandl/kscript kotlinc options https://kotlinlang.org/docs/reference/compiler-reference.html