:tools eval

Run code, run (also, repls)

1. Description

This modules adds inline code evaluation support to Emacs and a universal interface for opening and interacting with REPLs.

1.1. Module flags

Display evaluation results in an overlay at point rather than the minibuffer. That is, unless the results are too big (<5 lines), in which case it falls back to the minibuffer/popup buffer.

1.3. Hacks

  • Quickrun has been modified to:
    • Use only one output window, in case of consecutive execution of code.
    • The quickrun window will resize itself to fit its output, once the underlying process is finished executing the code.

2. Prerequisites

This module has no direct prerequisites.

However, many languages will require that you install their interpreters, code runners and/or repls to power the functionality of this module. Visit the documentation of their respective :lang module for instructions.

3. Usage

3.1. Inline Code Evaluation

Quickrun can be invoked via:

  • M-x +eval/buffer (or gR, or M-r)
  • M-x +eval/region
  • M-x +eval/region-and-replace
  • Evil users can use the gr operator to select and run a region.

3.2. REPLs

Invoked via:

  • SPC o r or :repl will open a REPL in a popup window. SPC o R or :repl! will open a REPL in the current window. If a REPL is already open and a selection is active, it will be sent to the REPL.
  • M-x +eval/open-repl-other-window (SPC o r)
  • M-x +eval/open-repl-same-window (SPC o R)
  • M-x +eval/send-region-to-repl (SPC c s) while a selection (and REPL) is active

4. Configuration

4.1. Register a REPL for a major-mode

REPLs are defined for most languages Doom supports. Check that language module’s README.org to see if it does (and if it requires additional setup).

To use them, you may use M-x +eval/open-repl-other-window, M-x +eval/open-repl-same-window, :repl (for evil users) or the default binding: SPC o r. These will open a REPL in a popup window.

You can simply call that mode’s REPL command manually. e.g. M-x ielm, but this will bar you from the benefits of Doom’s REPL system (like send-to-repl functionality).

Otherwise, you can define your own for a specified major mode:

(set-repl-handler! MAJOR-MODES FUNCTION)

MAJOR-MODES is a single major mode symbol or a list of them.

FUNCTION should return a repl buffer. Any window changes in this function are ignored, then the REPL is opened in a popup window. e.g.

(defun +lua/open-repl ()
  (lua-start-process "lua" "lua")
  (pop-to-buffer lua-process-buffer))

(set-repl-handler! 'lua-mode #'+lua/open-repl)

4.2. Change how code is evaluated in a major mode

Run regions or entire buffers with Quickrun. Output is show in a popup window.

Quickrun includes support for many languages, usually by sending text directly to interpreters or compilers. However, occasionally, you’ll find a language without support (like Crystal), or a language with better Emacs integration (like elisp).

Here’s how you define a “runner”:

(set-eval-handler! 'crystal-mode
  '((:command     . "crystal")
    (:exec        . "%c %s")
    (:description . "Run Crystal script")))

A simpler version is simply to use the path to the binary:

(set-eval-handler! 'groovy-mode "groovy")

Or if you’d rather run an elisp command:

(set-eval-handler! 'emacs-lisp-mode #'+emacs-lisp-eval)

5. Troubleshooting

There are no known problems with this module. Report one?

6. TODO Appendix

This module has no appendix yet. Write one?