Bidi paragraph direction in terminal emulators

[Ken Whistler via Unicode]

Egmont,

On 2/9/2019 11:48 AM, Egmont Koblinger via Unicode wrote:
> Are there any (non-CJK) scripts for which crossword puzzles don't exist?

There are crossword puzzles for Hindi (in the Devanagari script). Just 
do an image search for "Hindi crossword puzzle".

But the conventions for these break up words into syllables fitting into 
the boxes, and the rules for that are complex. You have to allow for the 
placement of dependent vowels, which may take up extra space left or 
right, as well as consonant clusters, which would be expressed often as 
conjuncts in Sanskrit, but which in Hindi are more commonly rendered as 
dead consonant sequences. So the "stuff in a box" is:

1. Inherently proportional width.

2. Inherently multi-character in content. (underlying 1 to 3 or more 
characters per cell)

This is the kind of compromise you would have to have to make for almost 
any Indic script, to enable a rational approach to building crossword 
puzzles that make sense.

And in a terminal context, you probably would not get acceptable 
behavior for Hindi if you tried to just take all the "stuff in a box" 
chunks and tried to lay them out directly in a line, as if the script 
behaved more like CJK.

The existence proof of techniques to cut up text into syllables that 
enable crossword puzzle building, is not the same as a determination 
that the script, ipso facto, would work in a terminal context without 
dealing with additional complex script issues.

At any rate, this is once again straying over into the issue of whether 
terminals can  be adapted for the requirements of shaping rules for 
complex scripts -- rather than the nominal subject of the thread, which 
has to do with bidi text layout in terminals.

--Ken