Kotlin Programming Cookbook

How it works…

Lambda functions are functions that are not declared but passed as an expression. In Kotlin, if a function receives an interface, we can replace it with a lambda. For example, the setOnClickListener function receives View.OnClickListener, so we can use a lambda:

fun setOnClickListener(listener: (View) -> Unit)someView.setOnClickListener({ view -> doSomething() })

Also, if there are no parameters to be passed to the lambda function, we can omit the arrow, and if the last parameter being passed is a function, we can move it outside the parentheses:

someView.setOnClickListener() { doSomething() }

Then, if the lambda function being passed is actually the only parameter, you can omit the parentheses completely:

button.setOnClickListener ...