IntRange.forEach

uses

Iterable.forEach

, so

(1..n).forEach { ... }

creates an

Iterator

, while

for (k in (1..n)) { ... }

is optimized to use a while-loop, not even creating the original

IntRange

object. Could

IntRange

receive its own

forEach

extension method to preserve this optimization, and perhaps receive additional optimizations for common methods like

map

?

Those are a little different. The for loop optimization is a compiler intrinsic, not a library function. Not that it invalidates your request, just that I don't think the two are very related.

@Ruckus it's a compiler intrinsic that a specialized inline function would be able to take advantage of, unlike an

Iterable

extension function.