on equivalence of software and hardware

This is an excerpt from an article by Tom Pittman in Dr. Dobb's Journal:

My introduction to virtual machines (VM) came as an off-hand remark at my first full-time job. Drexel Heater pointed out that regularly using my own library of Fortran subroutines amounted to designing my own programming language. Although never articulated so clearly, this idea pervades the programming community even today, particularly in C++ with the Standard Template Library, which by operator overloading actually changes the meaning of the Standard C operators. This concept gives you ultimate control over software design. Where Alan Kay predicts the future by inventing it, we predict software behavior by inventing the computer it runs on.


Every programming language is the machine language of some abstract computer whose machine operations are exactly that language's primitives. If you remove an operator from the language by not using it, you have effectively changed (limited) the computer. But let's increase, not reduce, the power of the machine. We do this by making the operations do more. That was Drexel's point about the subroutines.


C is more powerful than binary absolute, not because you can do more (you can't), but because the same programmer effort accomplishes more. A simple assignment—four keystrokes—hides a great deal of work the compiler does to allocate the variable: It chooses a representation of the value as well as the hardware instructions to copy those bits into that memory location. All this work is necessary, but not part of the problem the programmer is solving. Correspondingly, those four keystrokes are necessary, but not part of the specified program requirements. The most powerful programming language is where you state the requirements in a task-specific language, then the computer does it. That is the programming language you should write in.