Safari was against an explicit tail call syntax [0], and as part of that were against "TCO" as an optional optimization, however they are the first to implement

Safari was against an explicit tail call syntax [0], and as part of that were against "TCO" as an optional optimization, however they are the first to implement PTC. [0] https://github.com/tc39/ecma262/issues/535 https://github.com/tc39/ecma262/issues/535