On Sat, Nov 28, 2020 at 07:20:15PM +0100, Giovanni Piredda wrote: > I have in mind that the "Turing complete" expression describes a > system of manipulation of symbols (I helped now myself with > Wikipedia for finding the word "manipulation" in this context), by > which starting with a set of symbols and applying the manipulation > rules I obtain another set of symbols.
This is just to say that the parser of TeX is a complete programming language on its own. This means that it is undecidable whether a given program is parsable. TeX has no well-defined grammar, contrary to *ML languages (HTML, SGML, MathML) or TeXmacs. This is actually a very serious problem (it makes it impossible to write 100% reliable convertes) and a genuinly stupid one, because this problem is easy to avoid by design. > While I see a grammar as a set of rules that determine allowable > compositions of symbols, but they do not tell how to compose any set > of symbols. > > But you wrote that the grammar is Turing complete. Could you explain > more? Maybe a pointer to something to read, if it is to long to > write here. See also The Jolly Writer, section 1.8. > I am not going, at least for the moment, to write any comparison to > LaTeX in the article on TeXmacs. Sure, I also think that the page on TeXmacs is not the appropriate place for that. I just mentioned it to make the similarities and differences clear. > I have thought a bit on why LaTeX/TeX is so successful, One of the keys is that it cannot easily be converted to something else. Proprietary formats such as early M$ Word are another way to make this task hard. > The "markup" of TeX (I call it that way even if it is not markup) > for me is the easiest to read among all of the markup languages I > have seen (for mathematics especially, for other things too). > Perhaps this has been also one factor for success. Easy in appearance. If it is that easy, try writing a converter to some other format. Best wishes, --Joris _______________________________________________ Texmacs-dev mailing list Texmacs-dev@gnu.org https://lists.gnu.org/mailman/listinfo/texmacs-dev
