A modern programming language that makes developers happier.

kotlinlang

This is *NOT* tailrec `tailrec fun TreeNode.findMin(): TreeNode = left?.findMin() ?: this`
But this is: _`tailrec fun TreeNode.findMin(): TreeNode = if (left == null) this else left!!.findMin()`_
I am missing the concise syntax, why can’t the compiler smartly make the first one `tailrec`

I’m guessing because the compiler still needs to do a null-check (with the elvis operator) after calling `.findMin()` in the first example, because nulls get passed all the way through the call chain. In the second example, the null-check there is _before_ the call to `.findMin()`, so `findMin()` actually is the last call being made

from looking at your first code snippet, you don’t call recursively as the last statement, hence, as much as I understand it, it is not a tailrec function

<https://kotlinlang.org/docs/reference/functions.html#tail-recursive-functions>