To define a function in Kotlin, you have to use the fun keyword, as follows:
fun firstClass() {
println("First class function")
}
The preceding snippet demonstrates that we can declare functions as first class citizens. We can also define functions as class members, as follows:
class A {
fun classMember() {
println("Class member")
}
}
A local function is a function that is declared in another one, as follows:
fun outer() {
fun local() {
println("Local")
}
local()
}
In the preceding snippet, the local function is declared inside of the outer function. The local functions are only available in the scope of a function where they were declared. This approach can be useful if we want to avoid duplicate code inside of a function.
This section will cover the following topics:
- Functional programming
- Higher-order functions
- Lambdas