lean2/src/emacs

Emacs mode for lean theorem prover

Requirements

lean-mode requires Emacs 24 and the following packages, which can be installed via M-x package-install.

• dash
• dash-functional
• f
• s

The following packages are optional, but we recommend installing them to use full features of lean-mode.

• company
• flycheck
• fill-column-indicator

Both the optional and required packages will be installed for you automatically the first time you use lean-mode, if you follow the installation instructions below.

Installation

When Emacs is started, it loads startup information from a special initialization file, often called an "init file." The init file can be found in different places on different systems:

• Emacs will check for a file named .emacs in your home directory.
• With GNU Emacs, it is common to use .emacs.d/init.el instead.
• With Aquamacs, it is common to use ~/Library/Preferences/Aquamacs Emacs/Preferences.el.

On Windows, there are two additional complications:

• It may be hard to figure out what Emacs considers to be your "home directory".
• The file explorer may not let you create a file named .emacs, since it begins with a period.

One solution is to run Emacs itself and create the file using C-c C-f (control-C, control-F) and then entering ~/.emacs. (The tilde indicates your home directory.) On Windows, you can also name the file _emacs.

Put the following code in your Emacs init file:

(require 'package)
(add-to-list 'package-archives '("melpa" . "http://melpa.milkbox.net/packages/") t)
(when (< emacs-major-version 24)
  ;; For important compatibility libraries like cl-lib
  (add-to-list 'package-archives '("gnu" . "http://elpa.gnu.org/packages/")))
(package-initialize)

;; Install required/optional packages for lean-mode
(defvar lean-mode-required-packages
  '(company dash dash-functional flycheck f
            fill-column-indicator s))
(let ((need-to-refresh t))
  (dolist (p lean-mode-required-packages)
    (when (not (package-installed-p p))
      (when need-to-refresh
        (package-refresh-contents)
        (setq need-to-refresh nil))
      (package-install p))))

Then choose your installation method from the following scenarios, and add the corresponding code to your init file:

Case 1: Build Lean from source

;; Set up lean-root path
(setq lean-rootdir "~/projects/lean")  ;; <=== YOU NEED TO MODIFY THIS
(setq-local lean-emacs-path
            (concat (file-name-as-directory lean-rootdir)
                    (file-name-as-directory "src")
                    "emacs"))
(add-to-list 'load-path (expand-file-name lean-emacs-path))
(require 'lean-mode)

Case 2: Install Lean via apt-get on Ubuntu or via dpkg on Debian

;; Set up lean-root path
(setq lean-rootdir "/usr")
(setq-local lean-emacs-path "/usr/share/emacs/site-lisp/lean")
(add-to-list 'load-path (expand-file-name lean-emacs-path))
(require 'lean-mode)

Case 3: Install Lean via homebrew on OS X

;; Set up lean-root path
(setq lean-rootdir "/usr/local")
(setq-local lean-emacs-path "/usr/local/share/emacs/site-lisp/lean")
(add-to-list 'load-path (expand-file-name lean-emacs-path))
(require 'lean-mode)

Note: if you install homebrew in a custom location that is not the default location, please run brew info lean, and it will tell you where the lean-mode files are located. With that information, update the lean-emacs-path variable accordingly.

Case 4: Install Lean in Windows

;; Set up lean-root path
(setq lean-rootdir "\\lean-0.2.0-windows")
(setq-local lean-emacs-path "\\lean-0.2.0-windows\\share\\emacs\\site-lisp\\lean")
(add-to-list 'load-path (expand-file-name lean-emacs-path))
(require 'lean-mode)

Trying It Out

If things are working correctly, you should see the word Lean in the Emacs mode line when you open a file with extension .lean (for the standard Lean mode) or .hlean (for hott mode). If you type

check id

the word check will be underlined, and hovering over it will show you the type of id. The mode line will show FlyC:0/1, indicating that there are no errors and one piece of information displayed. Whenever you type, an asterisk should briefly appear after FlyC, indicating that your file is being checked.

Key Bindings and Commands

Key	Function
M-.	jump to definition in source file (lean-find-tag)
TAB	tab complete identifier, option, filename, etc. (lean-tab-indent-or-complete)
C-c C-k	shows the keystroke needed to input the symbol under the cursor
C-c C-g	show goal in tactic proof (lean-show-goal-at-pos)
C-c C-p	print information about identifier (lean-show-id-keyword-info)
C-c C-t	show type (lean-show-type)
C-c C-f	replace underscore by inferred value (lean-fill-placeholder)
C-c C-x	execute lean in stand-alone mode (lean-std-exe)
C-c C-l	execute lean in stand-alone mode (lean-std-exe)
C-c C-o	set option (lean-set-option)
C-c C-r	restart lean process (lean-server-reset-process)
C-c C-e	evaluate a lean comman (lean-eval-cmd)
C-c ! n	flycheck: go to next error
C-c ! p	flycheck: go to previous error
C-c ! l	flycheck: show list of errors

The Flycheck annotation FlyC:n/n indicates the number of errors / responses from Lean. An asterisk *FlyC:n/n indicates that checking is in progress. Clicking on FlyC opens the Flycheck menu.

To profile Lean performace on the file in the buffer, enter M-x lean-execute or choose Lean execute from the Lean menu, and add the option --profile.

Known Issues and Possible Solutions

Unicode

If you experience a problem rendering unicode symbols on emacs, please download the following fonts and install them on your machine:

• Quivira.ttf
• Dejavu Fonts
• NotoSans
• NotoSansSymbols

Then, have the following lines in your emacs setup to use DejaVu Sans Mono font:

(when (member "DejaVu Sans Mono" (font-family-list))
  (set-face-attribute 'default nil :font "DejaVu Sans Mono-11"))

You may also need to install emacs-unicode-fonts package.

• Run M-x package-refresh-contents, M-x package-install, and type unicode-fonts.

• Add the following lines in your emacs setup:

(require 'unicode-fonts) (unicode-fonts-setup)

Contributions
=============

Contributions are welcome!

If your contribution is a bug fix, create your topic branch from
`master`. If it is a new feature, check if there exists a
WIP(work-in-progress) branch (`vMAJOR.MINOR-wip`). If it does, use
that branch, otherwise use `master`.

Install [Cask](https://github.com/cask/cask) if you haven't already,
then:

 $ cd /path/to/lean/src/emacs
 $ cask

Run all tests with:

 $ make