Kotlin playground

playground.kt

import java.time.LocalDate

fun main(){
    // Currying and function types
    val sum = {a : Int, b : Int -> a + b}
    fun add(a: Int, b: Int) = a + b
    val add2 = {a : Int -> sum(a,2)}
    println(sum(2,2))
    println(add2(3))
    println(add(3,3))
    
    // Extension with trailing lambda
    fun String.sentenceCase() : String = this.lowercase().replaceFirstChar { it.uppercase() }
    val dayOfWeek = LocalDate.now().dayOfWeek.toString()
    val slogan = "BUGS ROCK"
    println("${slogan.sentenceCase()} on a ${dayOfWeek.sentenceCase()}")
    
    // Higher order function
    fun caser(arg: String, op: (String) -> String) = op(arg) 
    val result = caser(slogan, String::sentenceCase)
    println(result)
}