defun
From HandWiki
defun (short for "define function") is a macro in the Lisp family of programming languages that defines a function in the global environment[1] that uses the form:
(defun <function-name> (<parameter-1> <parameter-2> ... <parameter-N>) "optional documentation" <function-body>...)
Defining the function addnumbers
that adds two numbers:
;; Define a function that adds two numbers together: (defun addnumbers (number1 number2) (+ number1 number2)) (addnumbers 5 4) 9
Defining function square
that squares a number:
;; Define a function that squares a number: (defun square (x) (* x x)) (square 4) 16
Defining a function that returns the factorial
of a number
:
(defun factorial (number) "calculates the factorial" (if (= number 1) 1 (* number (factorial (- number 1))))) (factorial 6) 720
See also
References
External links
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The Wikibook Common Lisp has a page on the topic of: Defining functions in Common Lisp |
defun
in Emacs Lisp