See also: map and filter being the only 2 other functions implemented and both of them being less performant than their imperative equivalents; outright denial of any attempt at TCO because "Guido doesn't like recursion".
No, don’t ignore problems of TCO by saying “guys don’t like functional programimg”. Guido cleary states why he doesn’t like it: . Even though TCO is one of the ES6 standard, TCO also is largely denied by JS implementors (Firefox, Chrome, and Edge devs) because of the similar reasons. As a result, Safari is the only browser that supports TCO.  And Rust team is not eager to introduce TCO .
We will sometimes optimize for TCO, that issue is that we can’t guarantee it just yet.