I just got brian d. foy’s Learning Perl 6 from the library. It’s a pretty good book, though it’ll take a good few readings for some of Perl 6’s features to stick.
Since Perl 6 is built using Unicode from the ground up, it does two rather wonderful things when dealing with numbers:
regular expressions match numerals beyond 0â€“9: Ù¤ is as much four as 4
numeric constants can (pretty much) be expressed in terms of Unicode values in your Perl 6 source code. Assigning Ï€ to a variable does what you think it does. Dividing by Â¼ is the same as multiplying by, well, Ù¤.
So herewith a table (probably incomplete, and very unlikely to render properly for you) of Unicode glyphs accepted by Perl 6 as numeric values:
It’s been so long since I’ve programmed in Perl. Twelve years ago, it was my life, but what with the Raspberry Pi intervening, I hadn’t used it in a while. It’s been so long, in fact, that I wasn’t aware of the new language structures available since version 5.14. Perl’s Unicode support has got a lot more robust, and I’m sick of Python’s whining about codecs when processing anything other than ASCII anyway. So I thought I’d combine re-learning some modern Perl with some childish amusement.
Years ago, I worked in multilingual dictionary publishing. I was on the computing team, so we had to support the entry and storage of text in many different languages. Computers could display accented and special characters, but we were stuck with 8-bit character sets. This meant that we could only have a little over 200 distinct characters display in the same font at the same time. We’d be pretty much okay doing French & English together, but French & Norwegian started to get a little trying, and Italian & Greek couldn’t really be together at all.
We were very fortunate to be using Sun workstations in the editorial office. These were quite powerful Unix machines, which means that they were a fraction of the speed and capabilities of a Raspberry Pi. Suns had one particularly neat feature:
That little key marked â€œComposeâ€Â (to the right of the space bar) acted as a semi-smart typewriter backspace key: if you hit Compose, then the right key combination, an accented character or symbol would appear. Some of the straightforward compose key sequences are:
Like every (non-embedded) Linux system I’ve used, the Raspberry Pi running Raspbian can use the compose key method for entering extra characters. I’m annoyed, though, that almost every setup tutorial either says to disable it, or doesn’t explain what it’s for. Let me fix that for you …
and go to the configure_keyboardÂ â€œ4 Internationalisation Optionsâ€ â†’ â€œI3 Change Keyboard Layoutâ€ section. Your keyboard’s probably mostly set up the way you want it, so hit the Tab key and select <Ok> until you get to the Compose key section:
Choose whatever is convenient. The combined keyboard and trackpad I use (a SolidTek KB-3910) with my Raspberry Pi has a couple of â€œWindowsÂ® Logoâ€ keys, and the one on the right works for me. Keep the rest of the keyboard options the same, and exit raspi-config. After the message
Reloading keymap. This may take a short while
[ ok ] Setting preliminary keymap...done.
appears, you now have a working Compose key.
Using the Compose key
raspi-config hints (â€˜On the text console the Compose key does not work in Unicode mode â€¦â€™) that Compose might not work everywhere with every piece of software. I’ve tested it across quite a few pieces of software â€” both on the text console and under LXDE â€” and support seems to be almost universal. The only differences I can find are:
LXDE â€” (a. k. a. the mousey bit you see after typing â€˜startxâ€™) All characters and symbols I’ve tried work everywhere, in LXTerminal, Leafpad, Midori, Dillo (browser), IDLE, and FocusWriter (a very minimal word processor).
To find out which key sequences do what, the Compose key – Wikipedia page is a decent start. I prefer the slightly friendlier Ubuntu referencesÂ GtkComposeTable and Compose Key, or the almost unreadable but frighteningly comprehensive UTF-8 (Unicode) compose sequence reference (which is essentially mirrored on your Raspberry Pi as the file /usr/share/X11/locale/en_US.UTF-8/Compose). Now go forth and work that Compose key like a boÃŸ.