I don’t know the actual reason. It may have been a desire to keep flexibility in the language design by not imposing TCE rules. I think one reason is that you c

I don’t know the actual reason. It may have been a desire to keep flexibility in the language design by not imposing TCE rules. I think one reason is that you can’t have a tail call if you need to free things afterwards, so changing the signature from taking an object to borrowing it could make calls to the function no-longer eliminatable. Rules for which calls are tail-calls can already be confusing to people in simpler languages. I think they also make debugging harder, aren’t used much in higher-level code, and aren’t necessary if you have good looping constructs.