One of the issues with Java is that it is two levels of language. You compile Java into Java Byte code which is further compiled into native machine code. There

One of the issues with Java is that it is two levels of language. You compile Java into Java Byte code which is further compiled into native machine code. There is no concept of tail call recursion in Java Byte code. So, it is difficult to propagate the semantics. So it really has to be a programmer or compiler optimization to implement the tail call optimization into the generated intermediate bytecode before that is further compiled. .NET is an interesting contrast. The equivalent of Java Bytecode in .NET (CIL) does have the concept of tail calls. This allows a functional language like F# to be compiled to the intermediate form without losing the tail call concept. It is still up to the first level compiler though. C# for example does not support tail calls even though it’s intermediate target (CIL) does.