How to evaluate an Elisp expression in Emacs?

How to evaluate an Elisp expression in Emacs?

If you put point at the end of an sexp and type C-j Emacs will evaluate the expression and print the result straight into the buffer. Note: If you use paredit, be aware that it rebinds the key! The scratch buffer is a poor substitute for a proper REPL, but thankfully Emacs does come with one of those too.

Is there a way to evaluate Elisp in eshell?

You can evaluate elisp in Eshell directly from the prompt, with some limitations. I have covered this in greater detail in my article on Mastering Eshell. That just about covers evaluating code in Emacs, from one-liners to entire buffers of code.

Why is C-X C-E a poor tool for evaluating Elisp?

There are a couple of limitations that make C-x C-e a poor tool to use if you are writing and testing elisp code, because it cannot update variables declared with defvar or defcustom, and it goes with saying that having to move point to the end of the expression every time you want to eval the sexp is annoying as well.

Is there a lexical binding for Emacs Lisp?

Lexical Binding has recently been added to Emacs, it will take a while for this to permeate. Like all Lisps, Emacs Lisp has macros which you can read about in the manual at your leisure. The best, most comprehensive resource on Emacs Lisp is the manual.

How to use a function as a replacement string in Elisp?

You can use a function as your replacement string. (new in emacs 22, released in 2007) In the replace string prompt, give , (function_name), where function_name is your elisp function. The function needs no argument. Its return value is used as the replacement string.

What does auto complete do in emacslisp buffer?

Try hitting ‘f1’ or ‘C-w’ when completing something in an EmacsLisp buffer. And it has a separate notion of metadata, which it shows in the echo area, that can be used to quickly show the function’s argument list, for example. AutoComplete can display a candidate’s documentation, but it uses third-party libraries for that.

What’s the difference between companymode and emacslisp?

CompanyMode is more feature-rich, actually. For example, as long as the source supports that, it can show a documentation or a definition buffer without quitting the completion interface. Try hitting ‘f1’ or ‘C-w’ when completing something in an EmacsLisp buffer.

Which is the best programming mode for Emacs?

Emacs Lisp Mode. Emacs Lisp Mode is one of the best ProgrammingModes that comes with Emacs for working with EmacsLisp. Emacs Lisp Mode is enabled for any files ending in .el or when editing the Emacs InitFile. Emacs Lisp Mode is used for EvaluatingExpressions. Indentation is available with ‘TAB’.

Which is the best tool to install yasnippets?

yasnippet-snippets – a snippet collection package maintained by AndreaCrotti. It can be installed with M-x package-install RET yasnippet-snippets if you have added MELPA to your package sources. yasmate a tool which is dedicated to converting textmate bundles into yasnippet snippets.

Can You import TextMate templates into yasnippet?

The snippet syntax is inspired from TextMate’s syntax, you can even import most TextMate templates to YASnippet. Watch a demo on YouTube. Add the following in your .emacs file: Add your own snippets to ~/.emacs.d/snippets by placing files there or invoking yas-new-snippet.

How to get the major mode of the buffer?

(with-current-buffer buffer-or-string major-mode)) with-current-buffer will restore your buffer when it returns. A simple way to do this is to use the buffer-local-value function since major-mode is a buffer-local variable: Just extending from previous answers – call with no arguments to get the current buffer’s mode:

How does the scratch buffer work in Emacs?

The Emacs *scratch* buffer comes with a few useful additions over the regular Emacs-Lisp mode that makes it useful for throw-away scripts and quick code evaluation. If you put point at the end of an sexp and type C-j Emacs will evaluate the expression and print the result straight into the buffer.

Which is the eval last sexp in Emacs?

The facilities that are in place in Emacs to do this depend on the major mode you are using (and, rarely, your mode’s syntax table) but most modes still expose C-x C-e, which is bound to eval-last-sexp.

Is the scratch buffer a proper REPL in Emacs?

The scratch buffer is a poor substitute for a proper REPL, but thankfully Emacs does come with one of those too. This is a fantastic, and hidden, gem in Emacs: a proper REPL.

What are the advantages of using ielm in Emacs?

Because ielm inherits from comint you get all the advantages that provides, like a command history and so on. You also get limited completion support with TAB, which is very nice. Another useful feature is the concept of a working buffer – a buffer through which your changes are evaluated.