How do I differentiate between normal and insert modes when binding keys in vi-mode?

[g-gundam]

I want to create a key binding that should only be in effect when lem is in vi-mode and normal mode. While in insert mode, the binding should do nothing. How do I do that? How do I differentiate between normal and insert mode in code?

To provide some context, what I'd eventually like to do is create a space menu like the ones Spacemacs and Doom Emacs have.

[vindarel]

Hello, what about this:

(define-key lem-vi-mode:*normal-keymap*
  "g a"
  'beginning-of-defun-on-function)

(define-key lem-vi-mode:*insert-keymap* "C-n" 'lem/abbrev:abbrev-with-pop-up-window)

While in insert mode, the binding should do nothing. How do I do that?

I should have answered this.

How do I differentiate between normal and insert mode in code?

and this wouldn't be necessary now.

[g-gundam]

@vindarel Thank you for your answer. I feel like I'm so close to having a space menu now, but I can't get it to bind SPC. Here's what I have so far.

;; SPC
(defvar *space-keymap*
  (make-keymap :name '*space-keymap*)
  "The root keymap for the space menu.")
;; SPC f
(defvar *space-f-keymap*
  (make-keymap :name '*space-f-keymap*)
  "file menu")
(define-keys *space-f-keymap* 
  ("f" 'lem-core/commands/file:find-file)
  ("F" 'lem-core/commands/file:find-file-recursively))
;; SPC t
(defvar *space-t-keymap*
  (make-keymap :name '*space-t-keymap*)
  "toggle menu")
(define-keys *space-t-keymap* 
  ("s" 'lem-core::list-color-themes)
  ("w" 'lem-core/commands/window::toggle-line-wrap))

(define-keys *space-keymap* 
  ("f" *space-f-keymap*)
  ("t" *space-t-keymap*))
(define-key *global-keymap* "C-z" *space-keymap*) ; alternative leader
(define-key lem-vi-mode:*normal-keymap* " " *space-keymap*) ; FIXME: doesn't work
(define-key lem-vi-mode:*normal-keymap* "g" *space-keymap*) ; works

The bottom 3 lines are where I tried to setup some leaders. C-z and g both work, but " " does not, and that's the one I really wanted. What am I doing wrong there?

[g-gundam]

Nevermind. I figured it out.

(define-key lem-vi-mode:*normal-keymap* "Space" *space-keymap*)  ; This works.

Now if only I could get something like which-key...