Configuring Lem

Lem reads a lisp configuration file at startup:

$HOME/.lem/init.lisp

You might want to start it with:

(in-package :lem)

so you won't need to prefix all variables and commands.

When we eval lisp expressions with M-:, the default *package* is CL-USER. You can change it to Lem's package, so that it's easier to write Lem commands:

(lem-lisp-mode/internal::lisp-set-package "LEM")

Describe available keybindings

Use M-x describe-bindings or M-x documentation-describe-bindings.

How to find which keymap is in action and should be modified?

I didn't find. You can do M-: and enter (lem:current-mode-keymap), but it does not show in which package this keymap is defined.

Probably we should add information about keymaps into the output of the describe-bindings?

Defining key bindings

Let's pretend you want to make C-s C-w to search a symbol at point. By default, C-s turns on Isearch minor mode which has it's own keymap. To do what we need, we have to add a C-w key to this keymap like that:

(lem:define-key lem.isearch:*isearch-keymap*
   "C-w"
   'lem.isearch:isearch-forward-symbol-at-point)

To make a key execute more than one actions, create a command with define-command. For example:

(define-command test () ()
  (let ((p (lem:current-point)))
    (lem:buffer-start p)
    (lem-vi-mode/commands:vi-mode-move-to-end-of-line)))

Changing between vi-mode and emacs-mode

Use (lem-vi-mode:vi-mode) in the init file (or M-x vi-mode / emacs-mode).

What is the current mode? (lem::current-global-mode)

Paredit

(lem-paredit-mode:paredit-mode)

Start Paredit automatically with Lisp files:

;; thks @sasanidas
(add-hook lem:*find-file-hook*
          (lambda (buffer)
            (when (eq (buffer-major-mode buffer) 'lem-lisp-mode:lisp-mode)
              (change-buffer-mode buffer 'lem-paredit-mode:paredit-mode t))))

If you want to start in vi-mode at start-up, add the command to the init file.

Use shift-TAB in the completion window

this allows to go to the previous line:

(define-key completion-mode-keymap "Shift-Tab" 'completion-previous-line)

it is not part of the Lem 2.0 release but it was added right after.

How to load Quicklisp libraries

Do as usual: use (ql:quickload "library") in a Lisp REPL, or clone a library that is not available in Quicklisp into your ~/quicklisp/local-projects/ directory.

Miscellaneous

Electric pair

Here's a simple hook that inserts a closing ")" when you write an opening "(":

(defun electric-pair (char)
  ;; @akasha
  (when (eq char #\()
    (insert-character (current-point) #\))
    (backward-char)))

(add-hook (variable-value 'self-insert-after-hook) 'electric-pair)

Change the modeline colors

If your theme (M-x load-theme) doesn't satisfy you, try this:

(define-color-theme "my-theme" (<Inherit your current theme>)
  (modeline-name-attribute :foreground "...")
  (inactive-modeline-name-attribute :foreground "...")
  (modeline-major-mode-attribute :foreground "...")
  (inactive-modeline-major-mode-attribute :foreground "...")
  (modeline-minor-modes-attribute :foreground "...")
  (inactive-modeline-minor-modes-attribute :foreground "...")
  (modeline-position-attribute :foreground "..." :background "...")
  (inactive-modeline-position-attribute :foreground "..." :background "...")
  (modeline-posline-attribute :foreground "..." :background "...")
  (inactive-modeline-posline-attribute :foreground "..." :background "...")
  )

(load-theme "my-theme")

See also

• https://gitlab.com/sasanidas/lem-config/-/blob/master/init.lisp
• https://github.com/vindarel/lem-init