How has being one of the three creators of AWK impacted your career?

As I said, many programmers know me for AWK, but the computer science research community is much more familiar with my theoretical work. So I initially viewed the creation of AWK as a learning experience and a diversion rather than part of my regular research activities. However, the experience of implementing AWK has greatly influenced how I now teach programming languages and compilers, and software engineering.

What I've noticed is that some scientists aren't as well known for their primary field of research by the world at large as they are for their useful tools. Don Knuth, for example, is one of the world's foremost computer scientists, a founder of the field of computer algorithms. However, he developed a language for typesetting technical papers, called TeX. This wasn't his main avenue of research but TeX became very widely used throughout the world by many scientists outside of computer science. Knuth was passionate about having a mathematical typesetting system that could be used to produce beautiful looking papers and books.

Many other computer science researchers have developed useful programming languages as a by-product of their main line of research as well. As another example, Bjarne Stroustrup developed the widely used C++ programming language because he wanted to write network simulators.

Would you do anything differently in the development of AWK looking back?

One of the things that I would have done differently is instituting rigorous testing as we started to develop the language. We initially created AWK as a 'throw-away' language, so we didn't do rigorous quality control as part of our initial implementation.

I mentioned to you earlier that there was a person who wrote a CAD system in AWK. The reason he initially came to see me was to report a bug in the AWK compiler. He was very testy with me saying I had wasted three weeks of his life, as he had been looking for a bug in his own code only to discover that it was a bug in the AWK compiler! I huddled with Brian Kernighan after this, and we agreed we really need to do something differently in terms of quality control. So we instituted a rigorous regression test for all of the features of AWK. Any of the three of us who put in a new feature into the language from then on, first had to write a test for the new feature.

I have been teaching the programming languages and compilers course at Columbia University, for many several years. The course has a semester long project in which students work in teams of four or five to design their own innovative little language and to make a compiler for it.

Students coming into the course have never looked inside a compiler before, but in all the years I've been teaching this course, never has a team failed to deliver a working compiler at the end of the course. All of this is due to the experience I had in developing AWK with Kernighan and Weinberger In addition to learning the principles of language and compiler design, the students learn good software engineering practices.. Rigorous testing is something students do from the start. The students also learn the elements of project management, teamwork, and communication skills, both oral and written. So from that perspective AWK has significantly influenced how I teach programming languages and compilers and software development.