Try It Yourself - SyntaxStudy Editor

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// Higher-order function accepting a function parameter
fun applyTwice(x: Int, operation: (Int) -> Int): Int =
    operation(operation(x))

// Returning a function
fun multiplier(factor: Int): (Int) -> Int = { n -> n * factor }

fun main() {
    // Lambda stored in a variable
    val double: (Int) -> Int = { x -> x * 2 }
    println(applyTwice(3, double))   // 12

// Trailing lambda syntax
    val result = applyTwice(5) { it + 10 }
    println(result)   // 25

// Returned function
    val triple = multiplier(3)
    println(triple(7))   // 21

// Function reference
    fun square(n: Int) = n * n
    println(applyTwice(4, ::square))   // 256

// Collection operations with lambdas
    val numbers = listOf(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)

val evens    = numbers.filter { it % 2 == 0 }
    val doubled  = numbers.map { it * 2 }
    val sumEvens = numbers.filter { it % 2 == 0 }.sumOf { it }

println(evens)    // [2, 4, 6, 8, 10]
    println(doubled)  // [2, 4, 6, 8, 10, 12, 14, 16, 18, 20]
    println(sumEvens) // 30

// Multi-line lambda with explicit parameter names
    val categorised = numbers.groupBy { n ->
        if (n % 2 == 0) "even" else "odd"
    }
    println(categorised)
}