1WithoutFunInterface.kt

interface Predicate {
    fun isTrue(): Boolean
}

fun main() {
    val predicate = object: Predicate {
        override fun isTrue() = 10 == (5*2)
    }

    println(predicate.isTrue()) // prints "true"
}

2FunInterface.kt

fun interface Predicate {
    fun isTrue(): Boolean
}

fun main() {
   val predicate = Predicate { 10 == (5*2) }
    
   println(predicate.isTrue()) // prints "true"
}