Quick Answer

Concise syntax for functional parameters

Understanding the Issue

Kotlin lambdas provide a concise way to pass function literals. They can be written outside parentheses when last parameter, and support implicit "it" parameter.

The Problem

This code demonstrates the issue:

Kotlin Error 
// Problem: Verbose anonymous class
view.setOnClickListener(object : View.OnClickListener {
    override fun onClick(v: View) {
        // ...
    }
})

The Solution

Here's the corrected code:

Kotlin Fixed 
// Solution: Lambda expression
view.setOnClickListener { view ->
    // ...
}

// With implicit 'it' parameter:
view.setOnClickListener {
    it.isVisible = false
}

// Storing lambdas:
val square: (Int) -> Int = { x -> x * x }

Key Takeaways

Use lambdas for concise functional programming patterns.