Major mode for Emacs for editing buffer written in the Hy language. This mode is only compatible with Emacs 24 and above.

hy-mode is available in the MELPA repository. Do this, if MELPA isn't already in your sources:

(require 'package)
(add-to-list 'package-archives
             '("MELPA" . "https://melpa.org/packages/" ))

Then run M-x package-refresh-contents to load the contents of the new repository, and M-x package-install RET hy-mode RET to install hy-mode.

To install, just copy hy-mode.el into a directory on your load path. Alernatively, you could always modify your load path to include a new directory. For instance:

$ mkdir ~/.emacs.d/hy-mode
$ cp hy-mode.el ~/.emacs.d/hy-mode/hy-mode.el

In your init file, (usually .emacs or .emacs.d/init.el), add this:

;; add the new dir to the load path
(add-to-list 'load-path "~/.emacs.d/hy-mode")
(require 'hy-mode)

When in hy-mode, you can launch a Hy REPL by launching a Lisp inferior process:

M-x inferior-lisp

You can customize the path (also special options to the REPL like --spy) to the Hy REPL by setting the variable hy-mode-inferior-lisp-command to point to Hy executable's path. This can be done via M-x customize-group RET hy-mode and setting hy-mode inferior Lisp command.

From your hy-mode buffer you can use the following default keybindings:

• C-M-x: send the whole function (top-level form) for evaluation in the REPL
• C-x C-e: send the expression at current point for evaluation
• C-c C-z: switch to the lisp buffer
• C-c C-l: load the file in REPL

Since hy-mode is a lisp like mode, it can use the goodness from some minor modes used for lisp such as smartparens or paredit minor modes which support excellent movement and navigation ability other than keeping the s-expressions balanced.

; eg: Adding paredit minor mode
(add-hook 'hy-mode-hook 'paredit-mode)

; Add smartparens-strict-mode
(add-hook 'hy-mode-hook #'smartparens-strict-mode)

; alternatively you could enable this to a bunch of lisp modes
(dolist (lisp-mode '(scheme emacs-lisp lisp clojure hy))
  (add-hook (intern (concat (symbol-name lisp-mode) "-mode-hook"))
		'paredit-mode))

RainbowDelimiters is another minor mode which highlights parentheses, brackets, and braces according to their depth. Each successive level is highlighted in a different color. This makes it easy to spot matching delimiters, orient yourself in the code, and tell which statements are at a given depth. Assuming you've already installed RainbowDelimiters you can enable it like this:

(add-hook 'hy-mode-hook #'rainbow-delimiters-mode)

Depending on your PYTHONPATH and Emacs path settings, invoking inferior Lisp may not work by default. You may need to customize the path to Hy REPL to something like:

(setq hy-mode-inferior-lisp-command "/path/to/python -i /path/to/hy-script.py")

More information about Hy can be found at http://hylang.org.