TITLE: Compilers and the Universal Machine AUTHOR: Eugene Wallingford DATE: September 03, 2015 3:26 PM DESC: ----- BODY: I saw Eric Normand's The Most Important Idea in Computer Science a few days ago and enjoyed it. I almost always enjoy watching a programmer have fun writing a little interpreter and then share that fun with others. In class this week, my students and I spent a few minutes playing with T-diagrams to illustrate techniques for porting, bootstrapping, and optimizing compilers, and Normand's post came to mind. So I threw a little purple prose into my classroom comments.
All these examples of building compilers by feeding programs for new compilers into old compilers ultimately depend on a single big idea from the theory of computer science: that a certain kind of machine can simulate anything -- including itself. As a result, this certain kind of machine, the Turing machine, is the very definition of computability. But this big idea also means that, whatever problem we want to solve with information, we can solve it with a program. No additional hardware needed. We can emulate any hardware we might need, new or old, in software. This is truly one of the most important ideas in computer science. But it's also an idea that changes how we approach problems in nearly every other discipline. Philosophically, it was a monumental achievement in humanity's ongoing quest to understand the universe and our place in it. In this course, you will learn some of the intricacies of writing programs that simulate and translate other programs. At times, that will be a challenge. When you are deep in the trenches some night, trying to find an elusive error in your code, keep the big idea in mind. Perhaps it will comfort you.Oh, and I am teaching my compilers course again after a two-year break. Yay! -----