emacs.md

Emacs

Setup

How to set things up varies a bit depending on how one manages one's Emacs, e.g. straight.el, Doom, etc. What's common to all situations is likely:

• Ensure a janet-mode is installed and configured.

• Configure emacs to prevent tabs from being used for indentation in janet buffers. I do this by putting (setq-default indent-tabs-mode nil) in my .emacs equaivalent.

• Clone this repository.

straight.el

• I add the following sort of thing to my .emacs-equivalent:

  (straight-use-package
    '(janet-editor-elf :host github
                       :repo "sogaiu/janet-editor-elf"
                       :files ("*.el" "janet-editor-elf")))
  
  (use-package janet-editor-elf
    :straight t
    :config
    ;; menu
    (add-hook 'janet-mode-hook #'jee-mode)
    ;; indentation
    (add-hook 'janet-mode-hook
              (lambda ()
                ;; line indentation
                (setq-local indent-line-function
                            #'jee-indent-line)
                ;; region indentation
                (setq-local indent-region-function
                            #'jee-indent-region))))
  

Doom

• Allegedly, the following is valid for Doom:

  (package! janet-editor-elf
    :recipe (:type git
             :host github
             :repo "sogaiu/janet-editor-elf"
             :files (:defaults ("janet-editor-elf/"
                                "janet-editor-elf/*"))))
  
  (use-package! janet-editor-elf
    :after janet-mode
    :config
    ;; menu
    (add-hook 'janet-mode-hook #'jee-mode)
    ;; indentation
    (add-hook 'janet-mode-hook
              (lambda ()
                ;; line indentation
                (setq-local indent-line-function
                            #'jee-indent-line)
                ;; region indentation
                (setq-local indent-region-function
                            #'jee-indent-region))))
  

Vanilla

• If you cloned to ~/src/janet-editor-elf, add the following to your .emacs-equivalent:

  (add-to-list 'load-path
               (expand-file-name "~/src/janet-editor-elf"))
  
  ;; menu
  (add-hook 'janet-mode-hook #'jee-mode)
  
  ;; indentation
  (add-hook 'janet-mode-hook
            (lambda ()
              (require 'janet-editor-elf)
              ;; line indentation
              (setq-local indent-line-function
                          #'jee-indent-line)
              ;; region indentation
              (setq-local indent-region-function
                          #'jee-indent-region)))
  

package.el

• Sorry, no support for that. The Vanilla instructions should work though.

Usage

Indentation

Indentation of lines should work via Tab and happen automatically via Enter -- though these might depend on per-user Emacs settings.

For indentation to work appropriately, a buffer should not contain any tab characters.

One way to remove existing tabs is to use the untabify command after selecting buffer content that contains tabs.

One way to prevent additional tabs from being inserted is to utilize indent-tabs-mode. As mentioned earlier, I have (setq-default indent-tabs-mode nil) in my .emacs equaivalent.

There is a separate implementation for indent-region. Its behavior differs a bit from repeatedly applying indent-line to lines in a region, but it should also be faster.

To illustrate, consider the following code:

(def a
  ``
    hello
    there
  ``)

If one were to apply indent-line manually to each line, the result would be:

(def a
  ``
  hello
  there
  ``)

Note that the leading space from some lines within the long string have been changed. This is not likely to be what one wants when indenting the region. indent-region should preserve such whitespace, leaving the long string unchanged.

Note that pressing Enter within a long string may lead to indentation of the line the cursor was just on (which may change the leading whitespace). One way to prevent that from occuring is to use C-q C-j (i.e. applying the Emacs command quoted-insert to C-j) instead of Enter for such lines.

Wrapping and Unwrapping

To wrap a form with (tracev ...), put the cursor over the first character of a form and use M-x jee-tracev-wrap.

For example, to wrap (+ 1 1), put the cursor on ( and then execute the command.

To unwrap a form that is contained in (tracev ...), put point on some character of the (tracev ...) form and use M-x jee-tracev-unwrap.

For example, to unwrap (tracev (+ 1 1)), put the cursor on any of the characters in (tracev (+ 1 1)) and then execute the command.

A similar pair of things is possible for use with (comment ...) via:

• M-x jee-comment-wrap
• M-x jee-comment-unwrap

There is also a command to wrap a region:

• M-x jee-comment-wrap-region