Why is this not possible:

fun interface A {
    fun foo(b: Int = 42) // Single abstract member cannot declare default values
}

Yes, I want to keep the

fun

modifier to use it as a

FunctionalInterface

A { }.foo()

I am not sure if it is allowed for interface

@Umar Ata

fun interface

is valid and defines functional interfaces

@Joffrey What do you mean? The parameter of the body?

A { i -> // this?

}

Even with default values in the definition (the interface), you still would need to declare the variables in the body, implementation. If you mean calling the (single) member

foo

, the compiler is able to infer the correct overload, like its normal behavior with default values. Or do you mean this:

val a: (Int) -> Unit = A { }

? This does not compile, because even a

fun interface

does not inherit from

KFuction

(and its

invoke

) by default.

I meant the very last part: using an instance of the fun interface where a function is expected. I thought SAM conversions were supposed to work in that case, but I guess I was wrong