Simple Way to Understand Kotlin Scope Functions — let, run, with, apply, also

You have no idea when to use them because they are confusing. This article explains the common practical usages of these Scope functions.

If you look at the scope function examples in my previous post here, you can clearly tell that all those Kotlin Scope Functions (i.e. let, run, with, apply, also) can accomplish the same thing. They're all interchangeable, with slightly different in syntax.

Syntax Differences

Let’s understand the syntax differences between them first.

Source: kotlinlang.org

Note 1: All these scope functions are extension functions except for run and with. There are 2 run scope functions. One is with extension and another one without the extension function.

val str = "test"
// let, run, also, apply - are "extension functions"
str.run {
    println(this)
}

// with - is NOT an "extension function"
with(str) {
    println(this)
}

// run - could be NOT an "extension function"
run {
    println(str)
}