Elisp Functions
Table of Contents
1. Define Functions
Basic function definition has the form
(defun function_name (param1 param2 etc)
"docstring"
body)
When a function is called, the last expression in the function’s body is returned.
1.1. Optional Parameters
Add &optional
1.2. Rest Parameters
Add &rest, becomes a list.
2. Lambda Functions
3. Higher-Order Functions
3.1. apply
(apply FUNCTION &rest args_or_list)
Useful when we have a list and want to feed them as function parameters.
3.2. funcall
(funcall FUNCTION &rest args)
Useful when function name is a variable, whose value is known only at runtime.
3.3. identity
(identity ARGUMENT)
Simply returns the ARGUMENT.
3.4. ignore
(ignore &rest ARGUMENTS)
Ignore ARGUMENTS, and return nil
3.5. always
(always &rest ARGUMENTS)
Ignore ARGUMENTS, do nothing and return t.