Hands-On Design Patterns with Kotlin

Currying

Currying is a way to translate a function that takes a number of arguments into a chain of functions that each take a single argument. This may sound confusing, so let's look at a simple example:

fun subtract(x: Int, y: Int): Int {    return x - y}println(subtract(50, 8))

This is a function that returns two arguments. The result is quite obvious. But maybe we would like to invoke this function with the following syntax instead:

subtract(50)(8)

We've already seen how we can return a function from another function:

fun subtract(x: Int): (Int) -> Int {    return fun(y: Int): Int {        return x - y    }}

Here it is in the shorter form:

fun subtract(x: Int) = fun(y: Int): Int {    return x + y}

And here it is in an even shorter form:

fun subtract(x: ...