How to pass a lambda expression in Elisp
elisp, emacs, function, lambda
Solution
I think you need to use funcall:
Instead of `(url-formatter search)` you should have `(funcall url-formatter search)`.
Lisp expects the name of a function as the first element of a list. If instead you have a symbol associated with a lambda expression or function name, you need to use `funcall`.
Problem
So, I'm trying to make a generic web search function in Elisp: ``` (defun look-up-base (url-formatter) (let (search url) (setq search(thing-at-point 'symbol)) (setq url (url-formatter search)) (browse-url url)) ) ``` This function will just grab the word under the cursor, format the word for web search using url-formatter and then open up the search string in the web browser to perform the search. Next, I try to implement a function which will Google the word under the cursor, using the previous function as a basis. ``` (defun google () (interactive) (look-up-base (lambda (search) (concat "http://www.google.com/search?q=" search)))) ``` Emacs will not complain if I try to evaluate it, but when I try to use it, Emacs gives me this error message: ``` setq: Symbol's function definition is void: url-formatter ``` And I have no clue why this happens. I can't see anything wrong with the function, what am I doing wrong?