Functional Kotlin

Memoization

Memoization is a technique to cache results of pure functions. A memoized function behaves as a normal function, but stores the result of previous computations associated with the parameters supplied to produce that result.

The classic example of memoization is Fibonacci:

import arrow.syntax.function.memoizeimport kotlin.system.measureNanoTimefun recursiveFib(n: Long): Long = if (n < 2) {   n} else {   recursiveFib(n - 1) + recursiveFib(n - 2)}fun imperativeFib(n: Long): Long {   return when (n) {      0L -> 0      1L -> 1      else -> {         var a = 0L         var b = 1L         var c = 0L         for (i in 2..n) {            c = a + b            a = b            b = c         }         c      }   }}fun main(args: Array<String>) {   var lambdaFib: (Long) -> Long = { it } //Declared ahead to be used inside recursively   lambdaFib =