## 1 Introduction ¶

SLIME is the “Superior Lisp Interaction Mode for Emacs.”

SLIME extends Emacs with support for interactive programming in Common Lisp. The features are centered around `slime-mode`, an Emacs minor-mode that complements the standard `lisp-mode`. While `lisp-mode` supports editing Lisp source files, `slime-mode` adds support for interacting with a running Common Lisp process for compilation, debugging, documentation lookup, and so on.

The `slime-mode` programming environment follows the example of Emacs’s native Emacs Lisp environment. We have also included good ideas from similar systems (such as ILISP) and some new ideas of our own.

SLIME is constructed from two parts: a user-interface written in Emacs Lisp, and a supporting server program written in Common Lisp. The two sides are connected together with a socket and communicate using an RPC-like protocol.

The Lisp server is primarily written in portable Common Lisp. The required implementation-specific functionality is specified by a well-defined interface and implemented separately for each Lisp implementation. This makes SLIME readily portable.