spwhitton/ tech/ code/ pandoc-citeproc-preamble

pandoc-citeproc-preamble is a JSON filter for Pandoc which inserts a preamble before the output that the pandoc-citeproc filter appends to the document. This preamble might include a heading (e.g. “Bibliography”) and raw markup to format the bibliography for the output format.

  1. Installation
  2. Usage
  3. Rationale
  4. Source code
  5. Bugs
  6. License

Installation

Users of Debian 10 or later or Ubuntu 17.04 or later: apt-get install pandoc-citeproc-preamble. Users of Debian 9: enable backports, and then apt-get install -t stretch-backports pandoc-citeproc-preamble.

For users of other operating systems, you will need to build pandoc-citeproc-preamble from source. Probably the easiest way is to

  1. install Stack;
  2. ensure that ~/.local/bin is in your shell’s PATH; and
  3. run stack install pandoc pandoc-citeproc-preamble.

This should ensure that both pandoc and pandoc-citeproc-preamble are built against the same version of pandoc-types, which is required for them to interoperate.

Usage

Add --filter pandoc-citeproc-preamble somewhere after --filter pandoc-citeproc, e.g.

$ pandoc -s --filter pandoc-citeproc --bibliography=~/doc/mine.bib --filter pandoc-citeproc-preamble ~/doc/my_essay.mdwn -o ~/my_essay.pdf

In this case, since the output format is LaTeX, pandoc-citeproc-preamble will look for the preamble in the file data_dir/citeproc-preamble/default.latex where data_dir is your Pandoc user data directory, as reported by pandoc --version. You may specify a different preamble by setting document metadata like this:

$ pandoc ... --filter pandoc-citeproc-preamble -M citeproc-preamble=~/my_preamble.tex ...

Please see “Rationale”, below, for why it would defeat the purpose of this script to include a value for citeproc-preamble in your input file’s YAML metadata block.

Example preamble file

This is my ~/.pandoc/citeproc-preamble/default.latex, which was based on this guide.

\section*{References}
\setlength{\parindent}{-0.2in}
\singlespacing
\small
\setlength{\leftskip}{0.2in}
\setlength{\parskip}{8pt}
\vspace*{-0.4in}
\noindent

Rationale

One motivation for authoring with Pandoc is that one’s input files are agnostic with regard to the output format they will eventually be compiled to: it should not be necessary to include in one’s input file, for example, LaTeX code to format the bibliography.

When compiling to PDF (which is probably the most common case for users of pandoc-citeproc), formatting code is usually required to have the entries of pandoc-citeproc’s bibliography line up with each other; by default, all entries except the first will be indented. Another common customisation is to set up a hanging indent for bibliography entries.

Since pandoc-citeproc doesn’t provide any facility to add formatting control code to its output, pandoc-citeproc-preamble is necessary to avoid the user being forced to add their control code to the end of their input files, thereby losing the input file’s agnosticity with regard to output format.

Source code

pandoc-citeproc-preamble is written in Haskell.

Bugs

Please report bugs and submit patches/pull requests by e-mail.

License

Copyright (C) 2015-2016 Sean Whitton

pandoc-citeproc-preamble 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 of the License, or (at your option) any later version.

pandoc-citeproc-preamble 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 pandoc-citeproc-preamble. If not, see <http://www.gnu.org/licenses/>.