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In Kotlin, an inline function is a function modifier that suggests to the compiler to inline the function’s code at the call site, instead of invoking the function as a separate call. This can lead to performance improvements by reducing the overhead of function calls, especially in cases where the function is called frequently or in high-performance scenarios. Inline functions are often used in combination with higher-order functions, such as lambdas, to avoid the overhead of creating function objects.

Here’s an example of an inline function in Kotlin:

// Inline function definition
inline fun calculateSum(a: Int, b: Int): Int {
    return a + b
}

// Usage of the inline function
fun main() {
    val result = calculateSum(5, 3)
    println("Sum: $result")
}

In this example:

• We define an inline function calculateSum that takes two integer parameters a and b and returns their sum.
• The inline keyword before the fun keyword suggests to the compiler to inline the function’s code at the call site.
• In the main function, we call calculateSum with arguments 5 and 3 and store the result in the result variable.
• When the code is compiled, the call to calculateSum will be replaced with the actual implementation of the function at the call site.

Note that while using inline functions can improve performance in certain cases, it may also increase code size, especially if the function is large or used in multiple places. Therefore, it’s essential to use inline functions judiciously, especially in performance-critical scenarios.