What is the name for each of these ways to reference a function?

::funcName

funcName

funcName()

? The last one I believe is a function invocation, ie

() -> Unit

, but the first two confuse me.

The first is a function reference The second is only the name of the function, if that's already a variable pointing to a function then it's the same as the first I guess

function (or method) reference function name function invocation

fun funcName() : Unit { ... }

::funcName

is a function reference and can be cast easily to a lambda:

val funcRef : KFunction<Unit> = ::funcName // OK
val funcLambda : () -> Unit = ::funcName // OK
val givesCompileError: () -> Unit = funcRef // compiler error

funcName

is not possible in Kotlin. This will give a syntax error. This syntax denootes either a value/variable, parameter, field, etc.

funcName()

is calling the function, executing it, returning its return value.

// These do all the exact same
funcName()
funcRef.call()
funcLambda()

Sweet; thanks for all the info!