why can t functions defined as such ```fun foo = true``` be referenced as such ```val bar gt Boolean = foo``` or conversely ``` interface Foo val bar gt Boolean object Bar Foo override fun bar = true nope why not override val bar = true yep ```

why can t functions defined as such ```fun foo = true``` be kotlinlang #getting-started

Hullaballoonatic

06/02/2019, 5:43 PM

why can't functions defined as such:

fun foo() = true

be referenced as such:

val bar: () -> Boolean = foo

? or conversely:

interface Foo {
    val bar: () -> Boolean
}

object Bar : Foo {
    override fun bar() = true // nope. why not?
    override val bar = { true } // yep
}

06/02/2019, 5:49 PM

( )->Boolean

is function that returns boolean while

true

06/02/2019, 5:51 PM

one is a function and the other is a property holding a function reference

Hullaballoonatic

06/02/2019, 5:52 PM

i thought all functions WERE properties in the jvm?

06/02/2019, 5:58 PM

not in a way that is significant here

kotlin properties are implemented as jvm methods generally, so more like the other way around for this case

you can get a function reference using

::

if you need one

Hullaballoonatic

06/02/2019, 6:01 PM

righto, thanks for reminding me of that

06/02/2019, 6:03 PM

also a common gotcha in this area is that

foo::bar != foo::bar

- they're different instances

so be careful if you're trying to

collectionOfFunctionReferences.remove(foo::bar)