Programming Kotlin

Chapter 4External Iteration and Argument Matching

Count the number of times you’ve used for loops in your code. Shocking. Something that’s so widely used and fundamental as iterating should be fluent, concise, easy to write, and effortless to understand. Yet, in C-like languages, for loops have rather been primitive and verbose. Not so in Kotlin.

Kotlin provides both external iterators, used in the imperative style of programming, and internal iterators, used in the functional style. With external iteration, you, as the programmer, control the sequence of iteration explicitly, for example, with i++, i--, and so on. Internal iteration takes charge of the sequencing and lets programmers focus on the actions or computations for each iteration, ...