How to enter Greek characters in Emacs

Question

This page indicates that Greek letters can be inserted into Emacs by using M-i. However, Emacs 23.2.1 in a Debian Squeeze variant inserts the \"tab\" character when

Answer 1

The TeX input method is great for entering symbols in general, but if you're typing them with any frequency (e.g. if you're typing λ in some functional programming language), it will quickly become a drag to type \lambda every time you want to insert a Greek letter.

On the other hand, the Greek input method can be efficient for Greek letters, and is a clean solution since it leverages Emacs's built-in Greek support, but it isn't very useful as a default input method.

You can combine the benefits of both approaches like so (put somewhere in your Emacs init config):

(progn
  ;; conveniently enter math and greek symbols

  ;; leverage built-in input methods support in emacs to enter greek letters
  ;; by using the prefix ",."
  ;; adapted from https://emacs.stackexchange.com/a/53810
  (set-input-method "greek")
  (setq greek-map (quail-map))

  ;; add a translation rule to the TeX input method to delegate to
  ;; the greek input method
  (set-input-method "TeX")
  (quail-defrule ",." greek-map)

  ;; set default input method to TeX so that it can be activated
  ;; with C-\, e.g. to enter math or other symbols in general
  (setq default-input-method "TeX"))

This uses the TeX input method as the default, but augments it with a rule to temporarily delegate to the Greek input method when the prefix ,. is used.

Examples:

,.a => α
,.l => λ
,.v => ω
\to => →
\circ = ∘
^2 => ²
_i => ᵢ

Sources:

https://emacs.stackexchange.com/a/53810

https://stackoverflow.com/a/10197062/323874

https://stackoverflow.com/a/49765665/323874

https://emacs.stackexchange.com/a/419