TeXmacs 2.1.2 still uses guile 1.8.8 as its extension language. The TeXmacs-Scheme Developer Guide https://www.texmacs.org/tmweb/documents/manuals/texmacs-scheme.en.pdf mentions two online manuals.
Dybvig, The Scheme programming language. 2nd ed.(1996). Is this still up to date?
The Guile Reference Manual (v.1.8.8) which unfortunately has been taken off from the gnu.org site. Does anyone have a pdf-version of the file or know a link that is still working?
Will guile 3.0.8 or s7 be the future extension language? Following the discussions here on this forum I have the impression it might well be s7. How much does s7 differ from guile 1.8.8 from a “user” perspective?
Where should, in this transitory situation, the uninitiated best get stared to get acquainted with TeXmac’s extension language?