For Emacs Users - boot-clj/boot GitHub Wiki

In order for Emacs to recognise .boot files as valid Clojure source code, include the following in your .init file.

(add-to-list 'auto-mode-alist '("\\.boot\\'" . clojure-mode))

To recognize script files using shebang:

(add-to-list 'magic-mode-alist '(".* boot" . clojure-mode))