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Seeing is believing emacs minor mode

Seeing Is Believing is a ruby gem to evaluate Ruby code, recording the results of each line. This minor mode provides an easy way to run it from emacs on the current region or entire buffer.


Download the package and add it to your load path.

To install from MELPA, follow the instructions in the MELPA readme.

Once that's set up, you can run (package-install 'seeing-is-believing)

Alternatively, if you use spacemacs, add seeing-is-believing to your dotspacemacs-additional-packages variable in your .spacemacs file and reload your config.

Using the package

Enable the mode by typing M-x seeing-is-believing or by adding something similar to the following to your emacs init file:

(require 'seeing-is-believing)
(add-hook 'ruby-mode-hook 'seeing-is-believing)

When the mode is active you can run seeing is believing by typing C-c ? s. If you prefer the xmpfilter style of explicitly specifying where you want to see the output type C-c ? x. You can clear out the output from seeing is believing by typing C-c ? c.

You can change the keybinding shortcuts from the default of C-c ? by customising the seeing-is-believing-prefix variable (M-x set-variable <return> seeing-is-believing-prefix <return>).

You can also customize or set variables that affect how seeing-is-believing operates:

  • seeing-is-believing-executable can be set to the name of the program file for the executable (default "seeing_is_believing")
  • seeing-is-believing-max-length can be set to an integer that limits the length of lines produced, source plus comments (default 1000).
  • seeing-is-believing-max-results can be set to an integer that limits the number of results produced, when seeing-is-believing shows multiple results per comment (default 10),
  • seeing-is-believing-timeout can be set to a decimal number for the number of seconds seeing-is-believing runs before it times out or to 0 for no timeout (default 0), and
  • seeing-is-believing-alignment can be set to one of 'chunk, 'file, or 'line to change the way seeing-is-believing aligns its comments, on a chunk-by-chunk basis, across the whole file, or on a line-by-line basis, effectively no alignment (default 'chunk).

Either use the customize interface to set these, or set them in your init.el file:

(setq seeing-is-believing-max-length 150
      seeing-is-believing-max-results 10
      seeing-is-believing-timeout 10.5
      seeing-is-believing-alignment 'file)


Copyright 2015 John Cinnamond

This mode is distributed under the same licence as GNU Emacs.

GNU Emacs is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3, or (at your option) any later version.

GNU Emacs is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with GNU Emacs; see the file COPYING. If not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.


An emacs minor mode for running seeing_is_believing (






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