Kotlin return Function from Function

#kotlin #functional

https://grokonez.com/kotlin/kotlin-return-function-function

With Kotlin, we can define a function that chooses the appropriate logic variants for specific cases and returns one of them as another function. In this tutorial, we're gonna look at how to return Function from Function.

I. Technology

Java 1.8
Kotlin 1.1.2
II. Overview
To declare this kind of function, we specify a function type as its return type
To return a function, we write a return expression followed by a lambda, a method reference, or another expression of a function type
```
fun funcName(input: InputType): (FuncInputType1, FuncInputType2) -> FuncReturnType {

return [function type]          
}
```
III. Practice

1. Helper Class with function
```
package com.javasampleapproach.returnfunction
```

enum class Level { STANDARD, VIP }

class ChargeManagement {

companion object {
    fun getChargeCalculator(level: Level): (Order) -> Double {
        if (level == Level.VIP) {
            return { order -> 3 + 0.8 * order.quantity }
        }
        return { order -> 1.2 * order.quantity }
    }
}

}

https://grokonez.com/kotlin/kotlin-return-function-function