The Emacs package manager (ELPA), standard with Emacs 24+, includes the Factor major mode called Fuel.

Factor in Emacs

See Fuel on github for general Fuel usage.

Setup Emacs

0. Get latest Emacs

brew install emacs --with-cocoa

1. Install the Fuel package

M-x package-list

Find the Fuel package, mark it, and install.

2. Set the Factor root directory in .emacs

(setq fuel-factor-root-dir "/Applications/factor")

Run Factor Listener from within Emacs

M-x run-factor