Ten lines of code that changed my world

The BASIC print+goto loop might have been my first ever program too (in the 80s) but one thing for sure for me: it was definitely not “Hello, World”. I and others filled the screen with any number of silly things, random words, jokes and juvenile phrases, whatever, but for some reason, “Hello, World!” was a C thing, and I remember seeing it for the first time in a C class in high school, and then much more often in college.

I have memories of ‘poke’ as well. On the Atari 800 you could poke memory to change the keystroke repeat rate and delay before repeat started, so obviously we would turn down the delay to zero and turn up the repeat to max (it was maybe 60 characters per second), so anyone trying to type couldn’t hit the keys quickly enough to avoid repeating. You’d have to power-cycle the machine to fix it, so it was hilarious to 11 year old me.

Similar to his description of ‘poke’, but different mechanism - using debug.com on an IBM PC jr to edit the Ultimate III save files, and give myself maximum money and lives.

Good times!

Hmm. What a great question.

    while(1) { fork(); } 

Must have meant something to me, because it was in my Usenet sig. And then:

    exit(main(kfp->kargc, argv, environ));

from FreeBSD crt0; kind of a big moment for me to realize there was more C code underneath main().

Then:

    statements: /*E*/ | statement statements

The moment Yacc clicked for me; that line was profound but a more accurate depiction of the moment was realizing that all you were doing with the parser generator was building a tree, and that's what the side effects of each production were for: returning and plugging in tree nodes.

If there was a single line I could come up with for "double the size of the hash table when it fills up", that'd deserve a slot here.

Then, of course (we get to cheat because assembly):

    jmp .call
    .pop: pop esi
    ...
    .call: call .pop

The "delta offset" trick, which I believe came from x86 virus culture but was universal in 90s overflow exploits as a way to get position-independent references to strings and other memory things.

For sure:

    void walk(node *n) { if(!n) return; walk(n->left); visit(n); walk(n->right); }

I should figure out a way to fit a write-select(2) into a line because that's another "oh shit" moment for me.

Similarly: when Vern Paxson explained to me that he'd implemented TCP reassembly by simply opening up a file and using "seek" to place incoming segments in the right position. I could probably golf that down to a line! But it would be an annoying line.

I have been collecting small code snippets that would make for good tattoos and I have to say, some of these ones would probably make a good addition to the collection.

I'm partially more in favor of "red" instead of "hotpink" for CSS, but that's just me.

Here are 3 lines that capture something profound about Lisp: code can manufacture code that manufactures code:

———————

(defmacro twice (form)

  `(progn ,form ,form))

(twice (print "Reality"))

———————

twice doesn’t execute its argument twice. It rewrites the program itself before execution into:

(progn

    (print "Reality") 

    (print "Reality"))

> This tiny batch script allowed for a poor man’s `touch` on Windows, which I used extensively from Windows NT to Windows 7. I typed `touch filename.txt` in the Total Commander mini-shell to quickly generate new, empty files.

This is funny to me, because I associate touch more with updating the timestamp of an existing file, and that script would miserably (destructively) be failing at that.

For debugging CSS, I prefer something along the lines of:

    * {
      outline: 1px solid hotpink !important;
      outline-offset: -1px !important;
    }

As in most cases the above snippet doesn't reflow content.

Exercise to the reader is to turn the above into a javascript bookmarklet toggle, and to add support for shading margins and padding.

Such a lovely article. Thanks for sharing.

Another fun one for a bit of shenanigans:

  #define true ((rand()&15)!=15)

My first shipped code was an art thing. C64 Basic. Poke random characters to random locations on the screen. Random colors, screen and border too. On infinite goto loop. Radio Shack (IIRC) in the local mall used it on all their C64s.