elisp functions as parameters and as return value

Question

I have the following code

(defun avg-damp(f) 
    #\'(lambda(x) (/ (+ (funcall f x) x) 2.0)))

A call

(funcall (avg-damp #         


        

Answer 1

This style of programming does not work in plain Emacs Lisp. Emacs Lisp uses dynamic binding and languages like Scheme and Common Lisp are using lexical binding. Your code exposes the difference. See: Extent in Emacs Lisp

See also this question: How do I do closures in Emacs Lisp? and the 'solution' with lexical-let. lexical-let is an extension for Emacs Lisp in the "cl" package.

See also: since Emacs 24.1 there is optional lexical binding. Learn how to use it: using lexical binding.