On: Unicode programming, with examples in C

[lelf]

Only libucidata is big.

Reason — tons of data. Contrary to what other commenters said, it’s not (only) Unicode properties (they are tiny), but a lot more: from rules to spelling out the numerics, to transliteration, collation, to word/sentence segmentation (some of which are absolutely non-trivial and sometimes require dictionaries of special cases).

[gsnedders → lelf]

> word/sentence segmentation (some of which are absolutely non-trivial and sometimes require dictionaries of special cases)

Not just special cases: for Thai, you need a dictionary to do segmentation at all.