Week 4
expression evaluation: pld.cs.luc.edu/courses/271/spr18/demos/expressionsij.zip.
Notes: pld.cs.luc.edu/courses/271/spr18/mnotes/recursion.html#exprtrees
Demo of command-line expressions
With a calculator interface, things are a little different. Generally, the '(' key clears the display and starts a new subexpression. Operator keys might display the current operator on the screen. The ')' key acts like the '=' key for the current expression, displaying the results so far. galculator takes this approach.
The other alternative is to display the entire expression on the display line. qalculate does this.
This was a version of BSD Unix developed by William and Lynne Jolitz. It started as a port of BSD 4.3 to the 386. The project began in 1989; in 1988 the BSD team started work on removing all AT&T source from BSD Unix. The first release was in March 1992, but Dr Dobbs Journal ("traveling light without overbyte") published a serialized description of the porting process starting in January 1991.
Linux was announced in July 1991.
386BSD did not catch on. In 1993, the FreeBSD and NetBSD projects forked off.
Why did Linux succeed where 386BSD did not? Why didn't Linux degenerate into a multitude of forks? The persuasive skills of Linus Torvalds get some credit here. Perhaps another issue was that Torvalds was not seeking some "pure" solution; he was able to compromise, and to accept innovative pull requests from just about anyone.
Apple TLS
OpenSSL