Unicode and UTF-8

Page Break

0x0c is the page break character.

Those page break markers display something like "^L" in both vim and emacs.

Emacs

In emacs, we can insert them with C-q C-l and navigate between them with C-x [ and C-x.

From emacs, C-h i m Emacs RET m Pages RET.

Further tips

TODO

Vim

In vim, the digraph is FF, or with which means we can insert them with CTRL-K FF Or, insert the char with CTRL-V CTRL-L Then one can search for those page breaks with something like CTRL-V CTRL-L or ?CTRL-V CTRL-L followed by n or N to search forwards and backwards.

If CTRL-V is mapped to some other thing (e.g. paste text), CTRL-Q can also be used.

One example where I used this is for my The Little Schemer solutions, where code for each chapter is preceded by a page break character so I can easily navigate between the chapters.

See:

in vim help
:help insert.txt
:help i_CTRL-V
:help i_CTRL-Q

If we don’t want C-s to lock and terminal (which is unlocked with C-q):

bashrc
stty -ixon

Insert Special Characters

$ setxkbmap -option compose:caps

Then type CapsLock followed by:

  • .= → •

  • <> → ⋄

  • L- → £

  • E= → €

  • --. → en-dash

  • --- → em-dash

In vim/nvim, we can set digraphs like these (besides the ones that come pre-configured by default):

$ 0< ~/work/src/dotfiles/digraphs.vim sed ''
""
" Some extra digraphs I use frequently.
"

""
" • Bullet.
"
" Insert a bullet to make lists in plain plain text files and code
" comments. I am crazy about well-written, well-formatted textual
" content. Example:
"
" Some of my favorite games:
" • Super Mario World ---------: 1990;
" • Tomb Raider ---------------: 1996;
" • Heavy Metal: F.A.K.K. 2 ---: 2000;
" • Hitman Codename 47 --------: 2000;
" • Aliens versus Predator 2 --: 2001;
" ... many others...
"
digraphs oo 8226 " •

""
" ◦ White Bullet.
"
digraphs OO 9702

""
" · Middle Dot.
"
digraphs oO 183

""
" ‽ Interrobang.
"
digraphs ?! 8253

So if one types Ctrl+k followed by the char sequence, the special unicode character is inserted instead.

On VSCode, in the user settings.json, because I use the vim extensions, I have something like this which also works with Ctrl+k followed by char sequence:

Excerpt of ~/.config/Code/User/settings.json
{
  "vim.digraphs": {
    "oo": ["•", "0x2022"], // Bullet.
    "OO": ["◦", "0x25e6"], // White bullet.
    "oO": ["·", "0x00b7"], // Middle dot.
    "m-": ["—", "0x2014"], // Em dash.
    "?!": ["‽", "0x203d"], // Interrobang.
  },
}

Some Useful Unicode Chars and Symbols

INFINITY ∞

0x221e &infin;

LAMBDA λ

0x03bb

BOTTOM ⊥

0x22a5

Symbol For Horizontal Tabulation ␉

0x2409

Empty Set ∅

0x2205

I sometimes use the Empty Set ∅ (0x2205) on psql to more clearly visualize NULL values:

psql session
SQL> \pset null ∅
Null display is "∅".

SQL> SELECT col_a, col_b
FROM tbl_a RIGHT OUTER JOIN tbl_b
ON col_a = col_b;

 col_a | col_b
-------+-------
     ∅ |   101
   102 |   102
   104 |   104
   106 |   106
     ∅ |   108
(5 rows)