Binding modified key in evil mode

Question

I wanted to bind M-n to transpose-chars in evil insert state, and tried (define-key evil-insert-state-map "M-n" 'transpose-chars) But that didn't work. What should I do?

Answer 1

In (define-key KEYMAP KEY DEF) the KEY is internal representation of keys, where prefix keys must be \C- or \M-. A way to convert keys into internal representation is to use (kbd KEYS) function, where KEYS is string. In your question it could be two variants:

• (define-key evil-insert-state-ma‌​p "\M-n" 'transpose-chars)
• (define-key evil-insert-state-ma‌​p (kbd "M-n") 'transpose-chars)

https://www.gnu.org/software/emacs/manual/html_node/elisp/Key-Sequences.html