Passing a lambda to the last parameter
In Kotlin, there is a convention that if the last parameter of a function accepts a function, a lambda expression that is passed as the corresponding argument can be placed outside the parentheses:
val product = items.fold(1) { acc, e -> acc * e }
What is the purpose of this syntax?
This syntax gives Kotlin great DSL capabilities, it makes functions look like language constructions. For example:
with(car) {
startUp()
goToDestination()
}
Here with looks like it is language construction, whereas it is a simple function, receiving lambda as the last parameter.
And this leads to such elegant things like Kotlin HTML DSL