High Quality Content by WIKIPEDIA articles! Epsilon is a programmer`s text editor modelled after Emacs. It resembles Emacs not only in its default keybindings and layout, but also in the fact that it has a Turing-complete extension language in which much of its functionality is implemented. Unlike Emacs, Epsilon`s extension language, EEL (Epsilon Extension Language) is a dialect of C rather than a dialect of Lisp. Epsilon runs on DOS, Microsoft Windows, Linux, FreeBSD, Mac OS X and OS/2.