Emacs Lisp is a powerful programming language that is used to customize the popular text editor Emacs. In this beginner's guide, we will explore the history of Emacs Lisp, its syntax, and some of its best applications. We will also provide an example of how to write Emacs Lisp code.
History of Emacs Lisp
Emacs Lisp was created in the early 1980s by Richard Stallman, the founder of the Free Software Foundation. He created Emacs, the text editor, and needed a way to customize it. Emacs Lisp was born out of this need and has since become a popular language for Emacs customization.
Syntax of Emacs Lisp
Emacs Lisp is a dialect of Lisp, which is a family of programming languages that use lists as their primary data structure. It is a dynamically typed language, which means that variables can hold values of any type. Emacs Lisp code is written in files with a .el extension.
The basic structure of Emacs Lisp code consists of expressions, which are enclosed in parentheses. The first element of an expression is the function name, followed by the arguments enclosed in parentheses. Here is an example of a simple Emacs Lisp function:
(defun hello-world ()
(message "Hello, World!"))
This function defines a new function called "hello-world" that simply displays the message "Hello, World!" in the Emacs message buffer.
Applications of Emacs Lisp
Emacs Lisp is used primarily for customizing Emacs, but it has many other applications as well. One of its most popular uses is for writing extensions for other software programs. Because Emacs Lisp is an interpreted language, it is easy to write and test new code. It is also used for writing scripts, automating tasks, and creating macros.
Emacs Lisp can be used to create graphical user interfaces, interact with databases, and work with network protocols. It can also be used for scientific computing, text processing, and web development.
Example of Emacs Lisp Code
Let's take a look at a simple example of Emacs Lisp code. Suppose we want to create a new function that counts the number of words in the current buffer. Here is the code:
(defun count-words ()
(interactive)
(message "This buffer contains %d words." (length (split-string (buffer-string) " "))))
This function defines a new function called "count-words" that is interactive, which means it can be called from a keyboard shortcut. The function uses the built-in Emacs functions "buffer-string" to get the text of the current buffer, and "split-string" to split the text into words. It then uses "length" to count the number of words and displays the result in the Emacs message buffer.
Conclusion
Emacs Lisp is a powerful programming language that is used to customize Emacs and has many other applications as well. In this beginner's guide, we explored the history of Emacs Lisp, its syntax, and some of its best applications. We also provided an example of how to write Emacs Lisp code. With this knowledge, you can start exploring Emacs Lisp and using it to customize your own Emacs environment or to create your own programs.