Long ago, I came across a text editor function that replaced the word 'lambda' with the character 'λ'. I would like to do this in emacs. My preferences:
I would like to activate this function in certain modes only (activate it for Scheme-mode but turn it off for C-mode for example).
At work I still use an older version of emacs, so the solution should work for emacs22 and emacs23.
How should I proceed?
You create a mode hook, which replaces lambda with the Greek character.
(defun sm-greek-lambda ()
(font-lock-add-keywords nil `(("\\<lambda\\>"
(0 (progn (compose-region (match-beginning 0) (match-end 0)
,(make-char 'greek-iso8859-7 107))
nil))))))
Then you add this hook to your mode:
(add-hook 'emacs-lisp-mode-hook 'sm-greek-lambda)
sm-lambda-mode-hook by sm-replace-lambda or sm-greek-lambda. XXX-mode-hook is usually used to identify hooks ran by run-hook by the specified mode and thus to which you can use add-hook.
XXX-mode-hook and this custom one defined in the answer? Or at least point me to a useful documentation?
xxx-mode-hook is usually the name of the hook ran - with run-hooks - by the mode xxx. i.e. emacs-lisp-mode-hook is ran when the function emacs-mode is called. In this case, no hook is ran but a function is added to a hook. Look at the Elisp Manual (Hooks) for more information.
(add-hook 'emacs-lisp-mode-hook 'some-function) but (add-hook 'sm-lambda-mode-hook 'some-function) will never work unless you've some piece of code that does (run-hooks 'sm-lambda-mode-hook).