# pandoc-citeproc-preamble

## Synopsis

`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.

[Pandoc]: http://pandoc.org/ "Pandoc home page"

[pandoc-citeproc]: http://hackage.haskell.org/package/pandoc-citeproc

## Installation

`pandoc-citeproc-preamble` is available from Hackage, so if you have a
working Haskell installation on your machine you should just be able
to run `cabal install pandoc-citeproc-preamble`.  But I recommend
installing [stack][] and then

    $ git clone https://github.com/spwhitton/pandoc-citeproc-preamble
    $ cd pandoc-citeproc-preamble
    $ stack install

which will put the `pandoc-citeproc-preamble` binary in ~/.local/bin,
which should be in your PATH environment variable if you've set stack
up correctly.

[stack]: https://github.com/commercialhaskell/stack

## 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

Please see my [~/.pandoc/citeproc-preamble/default.latex][], which
was inspired by [this guide][].

[~/.pandoc/citeproc-preamble/default.latex]: https://github.com/spwhitton/dotfiles/blob/master/.pandoc/citeproc-preamble/default.latex "my default preamble"

[this guide]: http://kieranhealy.org/blog/archives/2014/01/23/plain-text/ "Plain Text, Papers, Pandoc"

## 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.

[hanging indent]: http://www.computerhope.com/jargon/h/hanginde.htm "description of hanging indent"