What is the main role of the 'let' construct in programming language?

In the Kotlin language (often used for Android development), the let construct is an extension function that allows you to execute a block of code with an object as an argument and return the result of that block. It is often used for safe handling of nullable types to avoid NullPointerException.

Example of using let:

val name: String? = "Android"
name?.let {
    println("String length: ${it.length}")
}

Here, the block inside let will only execute if name is not null. Inside the block, it refers to the name object.

Thus, the main role of let is to simplify working with objects, especially nullable ones, and to make the code more readable and safe.