tonsky.me VS janet-utf8

Updated a day after it was mentioned here :-)

https://github.com/tonsky/tonsky.me/commit/5fbbb373025be3758...

Regarding UTF-8 encoding:

“And a couple of important consequences:

- You CAN’T determine the length of the string by counting bytes.

- You CAN’T randomly jump into the middle of the string and start reading.

- You CAN’T get a substring by cutting at arbitrary byte offsets. You might cut off part of the character.”

One of the things I had to get used to when learning the programming language Janet is that strings are just plain byte sequences, unaware of any encoding. So when I call `length` on a string of one character that is represented by 2 bytes in UTF-8 (e.g. `ä`), the function returns 2 instead of 1. Similar issues occur when trying to take a substring, as mentioned by the author.

As much as I love the approach Janet took here (it feels clean and simple and works well with their built-in PEGs), it is a bit annoying to work with outside of the ASCII range. Fortunately, there are libraries that can deal with this issue (e.g. https://github.com/andrewchambers/janet-utf8), but I wish they would support conversion to/from UTF-8 out of the box, since I generally like Janet very much.

One interesting thing I learned from the article is that the first byte can always be determined from its prefix. I always wondered how you would recognize/separate a unicode character in a Janet string since it may have 1-4 bytes length, but I guess this is the answer.