Does anyone know why Knuth is writing some form of C? AFAIK none of the other TA...

JonathonW · on Dec 7, 2015

I haven't watched through the whole thing, but the C code I saw from skipping through looks like it's actually the output from CWEB [1], one of Knuth's literate programming tools. It combines C source code with long-form documentation, and it can either be preprocessed to TeX (to give that nice, pretty printed document that Knuth shows in the video) or to standard C source code to compile and run.

CWEB is one of Knuth's languages of choice, and he's got tons of code written in it on his website [2], including versions of some of the stuff he's demoing on-screen.

[1] http://www-cs-faculty.stanford.edu/~uno/cweb.html

[2] http://www-cs-faculty.stanford.edu/~uno/programs.html

kazinator · on Dec 8, 2015

Knuth has been using C for quite a long time now (he has not "changed now"), and it's fair to say that he likes it, based on the following:

More than 20 years ago, knuth ported his literate programming system to C, resulting in CWEB.

Here is a 1993 interview with Knuth about CWEB: http://tex.loria.fr/historique/interviews/knuth-clb1993.html

Key quote (on the subject of C):

I think C has a lot of features that are very important. The way C handles pointers, for example, was a brilliant innovation; it solved a lot of problems that we had before in data structuring and made the programs look good afterwards. C isn't the perfect language, no language is, but I think it has a lot of virtues, and you can avoid the parts you don't like. I do like C as a language, especially because it blends in with the operating system (if you're using UNIX, for example).

I can only guess that Knuth doesn't use C in TAOCP because C isn't defined in the kind of way that he thinks is suitable for teaching. Every port of C to some given architecture has different parameters which effectively render it a different dialect, and there are undefined behaviors all over the place.