JED is a highly customizable text editor offering most of
the commonly used features of EMACS without the proportions
of EMACS.  The default configuration uses EMACS keystrokes,
though WordStar keystrokes are available, and most any
keystrokes can be programmed.n  JED is customizable and
programmable in the language S-Lang, which can look like
Forth or C, depending on your preferences.

See also: https://space.mit.edu/~davis/jed/
See also: http://www.kondara.org/~g/jed.html