emacs-lisp

Start with a file header declaring lexical-binding, add author and package metadata, prefix all public symbols with the package name, write docstrings for every function, add autoload cookies to interactive commands, and end with (provide 'package-name) plus the footer comment.

Public functions use the package prefix like my-package-function, private functions use a double hyphen like my-package--helper, single-word predicates end in p (evenp), and multi-word predicates end in -p (buffer-live-p). Unused variables are prefixed with an underscore.

Always enable lexical binding by adding -*- lexical-binding: t; -*- to the file header. It provides better performance, proper closures, more predictable scoping, and improved byte-compiler optimization.

Use macros only when functions cannot work, such as when you need special evaluation order or to wrap body forms. Include a declare form for indentation and debug specs, and prefer backquote syntax over manual list construction.

Add an ;;;###autoload cookie directly before interactive commands and mode definitions. This lets users invoke the command without loading the entire package first, improving startup time.

Lambdas in hooks cannot be removed individually and make debugging harder. Define a named function instead and add it with a function quote, such as (add-hook 'emacs-lisp-mode-hook #'my-setup-function).