`for` loop vs `forEach` lambda ?

# codingconventions

[Hullaballoonatic]

for loop vs forEach lambda ?

[ghedeon]

Probably depends on the situation and style of programming. forEach is closer to FP and chained functions.

[Luke]

I tend to use classic for loop only on ranges. I prefer for(i in min..max) than (min..max).forEach. Nevertheless, I think it’s up to your liking more than actual conventions

[Hullaballoonatic]

✔️yeah, my preference is usually in readability.

i also, maybe arbitrarily, never do a loop in a single line, but i'm willing to write lambda's in a single line.

for (i in 0..lastIndex) { foo++ } -1

(i in 0..lastIndex).forEach { foo++ } +1

[Hullaballoonatic]

idk

[rakeeb]

you can’t break in a forEach (you could but you need to run it inside a run block). for me if you have a condition where you need to break out i’d go with for otherwise forEach

[gildor]

(i in 0..lastIndex).forEach { foo++ }

But this is invalid Kotlin code.
Valid version would be just:

(0..lastIndex).forEach { foo++ }

[gildor]

I agree that it of course depend on case.
For example if you have some lastIndex probably you have some collection (even some custom container, you can easily add extension for iterator), and in this case I don’t think that you need range for this, just .forEach() or for (i in collection)

[Hullaballoonatic]

yeah, i made a mistake.

[Hullaballoonatic]

my brain is tired today

[gildor]

also if we talk about ranges, not about iteration on some collection, than for cases when I would like to just do something N times from0 I also often use repeat:

repeat(max) { }

[gildor]

But the same problem as with forEach, no break, so for or while loops are the only choice in many cases

[gildor]

i’m willing to write lambda’s in a single line

In case of for you don’t have lambda, so because of this you can omit curly braces, so +1 to for

for (i in 0..lastIndex) foo++

[kenkyee]

was looking at this a bit more and noticed https://github.com/JetBrains/kotlin/blob/master/libraries/stdlib/common/src/generated/_Collections.kt uses a mix of both.
But also doesn't follow the guidelines mentioned here...i.e. no breaks needed in for loop but it's used.