Emacs: Evaluate Elisp Code

By Xah Lee. Date: . Last updated: .

To evaluate a single lisp expression, move your cursor to the right of the last closing parenthesis, and Alt+x eval-last-sexpCtrl+x Ctrl+e】.

To evaluate all elisp code in a text selection, Alt+x eval-region.

emacs lisp eval 2017 01 04
eval emacs lisp code basics.

Here's ways to eval elisp code, roughly in order of usefulness:

  1. eval-last-sexp → eval lisp expression to the left of cursor.
  2. eval-defun → eval function definition block the cursor is in. (the elisp code must be well-indended, otherwise emacs may have problem finding function.)
  3. eval-region → eval text selection.
  4. eval-buffer → eval whole buffer.
  5. load-file → eval a file. It prompts.
  6. eval-expression → prompts you to type code.

Emacs Lisp Command Line Interface (REPL)

Alt+x ielm to start emacs interactive emacs lisp shell.

emacs elisp REPL ielm 2017 01 04
emacs lisp interactive command line interface (REPL) ielm

I recommend working in a buffer instead of REPL.

Working in a buffer (sometimes called notebook inteface) allows you to use full editing power, and eval any expression, in any order, anytime, anywhere.

Emacs Lisp Basics

  1. Emacs Lisp Basics
  2. Overview of Text-Processing in Emacs Lisp
  3. Emacs Lisp Examples
  4. Evaluate Emacs Lisp Code
  5. Doc Lookup
  6. Search Doc
  7. How to Edit Lisp Code
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