Self-tutoring about comp-sci: the tutor mentions Perl’s reaction to if(var), var undefined. In yesterday’s post I mention about LISP and its reaction to a few “if” situations. In particular, LISP won’t tolerate being asked “if” about an undefined variable. LISP, …
Self-tutoring about Comp Sci: the tutor mentions true and false in LISP. An interesting aspect of every computer language is what it thinks of as “true” vs “false”. Many languages think 0 is false, while any other declared value, such …
Computer science: LISP: ideas about true and false Read more »
Self-tutoring about business: the tutor mentions the term “conglomerate.” conglomerate: a corporation that controls numerous smaller companies whose businesses may be otherwise unconnected. Back in the 80s, you heard the term “conglomerate” now and then; I never hear it today. …
Self-tutoring about people, events, and places of the past: the tutor reflects… An esker, by my understanding, is a raised bed of sand and/or gravel that was deposited as a glacier melted. It can be perhaps a few dozen feet …
Self-tutoring about people and events from the past: the tutor reflects… When I went to elementary school on the base, we never entered by a hallway entrance; rather, we had to wait outside our classroom to be let in by …
Self-tutoring about Linux: the tutor mentions braces. On the system I use, { Enter will open up a subshell into which you can enter one command per line, as if in a script file. On the last line I just …
Self-tutoring about awk: the tutor mentions the if(var) condition. Some computer languages allow if(x) as a condition; others insist an explicit comparison, such as if(x!=0). In my experience, awk allows if(x).
Self-tutoring about Canadian amphibians: the tutor reflects… When I was a kid in PEI, I don’t recall seeing frogs or toads, or hearing them at night. Then again, where I happened to live, there weren’t really any marshes, swamps, etc. …
Self-tutoring about [Li|U]nix: the tutor continues about grep capabilities. On the system I use, the + (one or more) operator will work with grep if escaped. With the -E option you don’t have to escape it. Therefore, grep “^t\w\+[.]txt” will …
Self-tutoring about Linux and Unix: Can one use Perl’s amazing regex features with grep? Perhaps some of them: the tutor begins… Perl’s convenient \w and \d work with grep, as-is, on the system I use. Frankly, I’m impressed with what …
[Li|U]nix: grep, part 2: a bit about character classes Read more »