I use the jnyqide editor/IDE which is part of the Nyquist distribution and
cross-platform. It knows the built-in Nyquist and XLISP functions and does
syntax highlighting and paren balancing. It's a very basic editor, so don't
expect lots of slick features.
Lately, I've been using emacs a lot in elisp mode alongside jnyqide. Emacs
automates indentation, I'm accustomed to the key commands, and it helps when
I'm editing Lisp, C, and documentation all in the same session. With
jnyqide, you select a text window and push the "load" button or type Ctrl-K
to: save the file, set the Nyquist current directory to that of the file,
issue a Lisp (LOAD ...) command to load the file. Once you've done this, you
can also edit the file in another editor, e.g. Emacs, save it, and type
Ctrl-K to jnyqide to reload the file for testing.
Edgar, if you'll send me your Emacs customizations, I'd be happy to put them
in the next release (coming very soon).