Android Development with Kotlin

Higher-order functions

A higher-order function is a function that takes at least one function as an argument, or returns a function as its result. It is fully supported in Kotlin, as functions are first-class citizens. Let's look at it in an example. Let's suppose that we need two functions: a function that will add all BigDecimal numbers from a list, and a function that will get the product (the result of multiplication between all the elements in this list) of all these numbers:

 fun sum(numbers: List<BigDecimal>): BigDecimal { var sum = BigDecimal.ZERO for (num in numbers) { sum += num } return sum } fun prod(numbers: List<BigDecimal>): BigDecimal { var prod = BigDecimal.ONE for (num in numbers) { prod *= num } return prod } // Usage val ...