QUOTE: TeX engines are batch document processors but worth looking into separately. Historically TeX had no shaping engines and basic shaping was done using macro packages and a variety of hacks. More recently though, XeTeX was invented. XeTeX simply outsources the shaping to an external library, ICU or Apple's ATSUI currently. XeTeX is a separate branch of the TeX evolutionary hierarchy than the mainstream pdfTeX though. The XeTeX creator is working on HarfBuzz on behalf of Mozilla now, and plans to port XeTeX to HarfBuzz eventually. In the long term though, pdfTeX's successor luaTeX should be made to do the same thing. There is more to Unicode support than just shaping, and in those areas the TeX engines can gain a lot by building on top of existing libraries. http://behdad.org/text/