Stop Using the Wrong Loop! From for to onEach: Ultimate Guide to Kotlin Loops

Kotlin provides various ways to loop through data, each suitable for different use cases. Below are the primary looping constructs in Kotlin and my opinion on which one suits which cases.

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Warning!

Don’t fight about imperative style or functional style looping! understand their merits and tradeoffs.

When to Prefer Imperative Looping?

1. Performance-Critical Code: Imperative loops can be more performant because they avoid the overhead of function calls and intermediate collections.
2. Complex Logic: When the logic inside the loop is complex, involving multiple statements, and early exits (return, break, continue etc), imperative loops can be clearer and more straightforward.
3. Mutable State: When the algorithm inherently involves changing the state over the course of the loop (e.g., updating a running total, managing an index) etc.

When to Prefer Functional Looping: