pandoc-include-code

A Pandoc filter for including code from source files.

You get to:

• Keep your examples and documentation compiled and in sync
• Include small snippets from larger source files without needing to keep track of line numbers
• Dedent included snippets

Usage

The filter recognizes code blocks with the include attribute present. It swaps the content of the code block with contents from a file.

Including Files

The simplest way to use this filter is to include an entire file:

```{include=docs/MyFile.hs}
```

You can still use other attributes, and classes, to control the code blocks:

```{.purescript include=docs/MyFile.purs}
```

Snippets

There is support for delimited snippets. Use a line comment of whatever kind you want, and enclose the snippet between start snippet <name> and end snippet <name>.

-- start snippet cool-thingy
main =
  putStrLn "I explain some cool concept in Haskell code."
-- end snippet cool-thingy

Or why not some C code:

// start snippet wow
int main() {
    printf("such performance");
}
// end snippet wow

NOTE: There can only be whitespace and a newline after the snippet name. This means that multi-line comments in C, Java, etc, will not work. Only single-line comments will.

Then, in your code block, specify the snippet name:

```{include=docs/MyFile.hs snippet=cool-thingy}
```

Ranges

If you want to include a specific range of lines, use startLine and endLine:

```{include=docs/MyFile.hs startLine=35 endLine=80}
```

Dedent

Using the dedent attribute, you can have whitespaces removed on each line, where possible (non-whitespace character will not be removed even if they occur in the dedent area).

```{include=docs/MyFile.hs dedent=4}
```

Conflicting Modes

"Snippet mode" and "range mode" cannot be used together.

Line Numbers

If you include the numberLines class in your code block, and use include, the startFrom attribute will be added with respect to the included code's location in the source file.

```{include=docs/MyFile.hs startLine=35 endLine=80 .numberLines}
```

Adding Direct Links

It is possible to add hyperlinks to the original source code file specified in the include attribute by adding the .includeLink class in your code block.

```{include=docs/MyFile.hs .includeLink}
```

Adding Base url for all CodeBlock links

A base url will be appended to all relative paths specified in the include attribute of each CodeBlock . It does not affect paths beginning with file: , C:, \, /,.... This can be done two option:

Option 1: YAML

Specify a base key along with the base url as the attribute in the YAML header:

    ---
    title:    All About Wonderland
    author:   Alice
    date:     November 2020
    base:     http://localhost:8000/
    ---

Option 2: Command Line

Add the base as a metavalue -M base=<base url> or --metavalue base=<base url> in the command line when calling pandoc.

pandoc --filter pandoc-include-code -M base=http://localhost:8000/  in.md -o out.html

NOTE: If the base url is specified in the metadata block, then by specifying a different base in the command line, it will override the original base.

Both of these options will add a hyperlink to the filepath defined in the include attribute linking to http://localhost:8000/source/sample.hs:

Overriding a specified base url

Adding a base attribute in the metadata block or the command line will affect all relative links in the CodeBlocks. To add an alternative base for a specific link, add the base as an attribute base=https.... to theCodeBlock:

```{.haskell .includeLink include=source/sample.hs snippet=animals base=<path>}
```

This adds a hyperlink to the filepath specified in the include attribute linking to ../source/sample.hs :

More Usage Examples

• The blog post Automating the Build of Your Technical Presentation shows practical examples of how to use this filter.

Install

Executables for Linux and macOS are available in the Releases page.

From Homebrew

You can use Homebrew to install this filter:

brew install pandoc-include-code

From Hackage

If you'd rather install using cabal or stack, you can use the following command:

cabal install pandoc-include-code

The package is available at Hackage.

Build

Requirements:

• Cabal or Stack, either works.

To install from sources, run:

git clone git@github.com:owickstrom/pandoc-include-code.git
cd pandoc-include-code
cabal configure
cabal install

Run

If you have installed from sources, and you have ~/.local/bin on your PATH, you can use the filter with Pandoc like so:

pandoc --filter pandoc-include-code input.md output.html

Usage with Hakyll

If you are using the Hakyll static site generator, you can use the filter by importing it as a library and using the snippet below.

Add pandoc, pandoc-types, and pandoc-include-code to your project dependencies, then define a custom Hakyll compiler using a Pandoc transform:

import Text.Pandoc (Format (..), Pandoc)
import Text.Pandoc.Walk (walkM)
import Text.Pandoc.Filter.IncludeCode (includeCode)

includeCodeTransform :: Pandoc -> IO Pandoc
includeCodeTransform = walkM (includeCode (Just (Format "html5")))

includeCodePandocCompiler :: Compiler (Item String)
includeCodePandocCompiler =
  pandocCompilerWithTransformM
    defaultHakyllReaderOptions
    defaultHakyllWriterOptions
    (unsafeCompiler . includeCodeTransform)

You can now use includeCodePandocCompiler instead of the default pandocCompiler in your Hakyll rules:

match "*.md" $ do
  route $ setExtension "html"
  compile $ includeCodePandocCompiler
    >>= loadAndApplyTemplate "templates/default.html" defaultContext
    >>= relativizeUrls

Changelog

CHANGELOG.md

License

Mozilla Public License Version 2.0