I praise the idea of making TCO explicit and guaranteed, but wonder if whole new keyword is necessary? It could be avoided by modifying `return` with another ke

I praise the idea of making TCO explicit and guaranteed, but wonder if whole new keyword is necessary? It could be avoided by modifying `return` with another keyword which is currently impossible at that place, for example return as foobar(x, n-1) return in foobar(x, n-1) override return foobar(x, n-1) final return foobar(x, n-1) It's a little surprising to see entirely new construct invented for something that is just a different implementation of `return`, after all, the end result of computation with tail-return is the same as with normal return, only performance differs.