Android Development with Kotlin

The last lambda in an argument convention

In Kotlin, higher-order functions are really important, and so it is also important to make their usage as easy as possible. This is why Kotlin introduced a special convention that makes higher-order functions simpler and clearer. It works this way: if the last parameter is a function, then we can define a lambda expression outside of the brackets. Let's see how it looks if we use it with the longOperationAsync function, which is defined as follows:

    fun longOperationAsync(a: Int, callback: ()->Unit) { 
        // ... 
    } 

The function type is in the last position in the arguments. This is why we can execute it this way:

    longOperationAsync(10) {
        hideProgress() 
    } 

Thanks to the last lambda in an argument convention, ...