I read that TeX was written in SAIL and re-writen in Pascal. Do we still use that version today? In my Linux distribution, I use TeX-Live. Does that also use the Pascal version?
Wikipedia says the last major revision was in 1982 and that it's quite stable. So only a few changes have been necessarily over the years.
I don't quite totally agree, since certain layout features are quite difficult to execute, and what if I don't like Pascal?
For my first issue, it may be possible to learn TeX (rather than LaTeX) and address these graphic design issues myself. Still I am rather curious about to layers, thanks.
What language is TeX implemented in?
From blog Implementing TeX in Clojure:
TeX source code is full of examples of what would not be considered good programming style today, such as:
- global variables
- one-character variables
- goto statements
- procedures spanning hundreds of lines;
- lots of macros;
- duplicate code;
- local variable reuse;
- single-threaded assumption is “everywhere”;
- mutability is just “pervasive”
texdoc tex
at the terminal is the documentation, containing the complete program in (theoretically) human-readable format. The same source code can be used to generate computer-readable program code.