Functional Kotlin

Generating lenses

Once Arrow's code generation is configured, you can add the @lenses annotation to the data classes that you want to have lenses generated for:

import arrow.lensesimport arrow.optics.Lensimport arrow.optics.modifytypealias GB = Int@lenses data class Memory(val size: GB)@lenses data class MotherBoard(val brand: String, val memory: Memory)@lenses data class Laptop(val price: Double, val motherBoard: MotherBoard)fun main(args: Array<String>) {   val laptopX8 = Laptop(500.0, MotherBoard("X", Memory(8)))   val laptopMemorySize: Lens<Laptop, GB> = laptopMotherBoard() compose motherBoardMemory() compose memorySize()   val laptopX16 = laptopMemorySize.modify(laptopPrice().set(laptopX8, 780.0)) { size ->      size * 2   }   println("laptopX16 = ...