Guile started off life as a knee-jerk NIH response from Richard about
TCL.[1] Is it more mature now since its inception?
While I like TCL and I like using it for certain applications, I do
not think it would make a proper extension language for XEmacs. The
Tk application exmh is certainly the strongest competitor for best
non-Emacs-based mailer (IMO).
Footnotes:
[1] I read the whole thread when it appeared. Please direct
commentary to /dev/null.