A modern programming language that makes developers happier.

kotlinlang

When is .forEach {} preferred, vs java-style for loop?  It looks like both get support from the language, e.g. destructuring for loop values

`forEach` uses an iterator, so if you care about that (you need your loop to be as performant as possible), then you should use the `for` loop, otherwise it's a matter of preference.

`forEach` is inlined and uses a `for` loop, so it should only use an iterator when `for` uses an iterator. `forEach` is a tail function call, so it is often preferable for working with flows and pipelines. It does not support things like `break` and `continue` however, but from my experience those don't often play well with flows and pipelines anyway, as there would usually be some sort of `filter` or something earlier in the pipeline to account for it.

For just a simple "I need to loop over this collection and do stuff with the elements", generally prefer `for`. For anything more complex involving multiple steps, `forEach` makes a good step in the chain.

IMO: only use `forEach` when it is meaningfully more useful, e.g.
```foo["bar"]?.forEach { ... }
```
is more work to express with `for`. but otherwise use `for`

&gt; it should only use an iterator when
&gt; 
<@U10EJRH2L> not true; it always uses an iterator because that's resolved before inlining happens. e.g.
```for (i in 1..10) {} // compiler optimizes this to an increment
(1..10).forEach {} // constructs range object, iterator, and boxes```

For the Kotlin coding conventions.

&gt;  Prefer using higher-order functions (`filter`, `map` etc.) to loops. Exception: `forEach`(prefer using a regular `for` loop instead, unless the receiver of `forEach` is nullable or `forEach` is used as part of a longer call chain).
<https://kotlinlang.org/docs/coding-conventions.html#loops>

<@UJQB4DJF7> Interesting, I thought I remembered that being included in the compiler intrinsics. That's good to know, thanks.