In the old days, when the computer was new, we coded directly to the machine. We had no assemblers. Still later we moved up to compilers. Note that the native language, the machine language of Hal algebra is equal to the compiler code of the computer. There is, of course, an assembly language for Hal algebra also.
Computer programs are sequential.
They are performed in the order they are presented. There are control commands to change the sequence of computer programs. Hal algebra has no sequence control because there is no sequence. All the codes of Hal algebra operate at the same time, all the time. Fetch works on the memory, which has been stuffed with programs and data.