There isare a wide variety of systems under this heading. The most extreme example is a Directly Executed Language, where the [[instruction set architecture]] of the computer equals the instructions of the HLL, and the source code is directly executable with minimal processing. In extreme cases the only compilation required is [[tokenizing]] the source code and feeding the tokens directly to the processor; this is found in [[stack-oriented programming language]]s running on a [[stack machine]]. For more conventional languages the HLL statements are grouped into instruction + arguments, and infix order is transformed to prefix or postfix order. DELs are typically only hypothetical, though they were advocated in the 1970s.<ref>See Yaohan Chu references.</ref>
In less extreme examples the source code is first parsed to [[bytecode]], which is then the [[machine code]] that is passed to the processor. In these cases the system typically lacks an assembler, as the compiler is deemed sufficient, though in some cases (such as Java) assemblers are used to produce legal bytecode which would not be output by the compiler. This approach was found in the [[Pascal MicroEngine]] (1979), and is currently used by Java processors.
