Text.BlogLiterately.Transform

Tools for putting together a pipeline transforming the source for a post into a completely formatted HTML document.

Transforms

data Transform

A document transformation consists of two parts: an actual transformation, expressed as a function over Pandoc documents, and a condition specifying whether the transformation should actually be applied.

The transformation itself takes a BlogLiterately configuration as an argument. You may of course ignore it if you do not need to know anything about the configuration. The --xtra (or -x) flag is also provided especially as a method of getting information from the command-line to custom extensions. Arguments passed via -x on the command line are available from the xtra field of the BlogLiterately configuration.

The transformation is then specified as a Kleisli IO Pandoc Pandoc arrow, which is isomorphic to Pandoc -> IO Pandoc. If you have a pure function of type Pandoc -> Pandoc, wrap it in a call to arr to produce a Kleisli arrow. If you have a function Pandoc -> IO Pandoc, wrap it in the Kleisli constructor.

For examples, see the implementations of the standard transforms below.

Constructors

Transform

Fields

getTransform :: BlogLiterately -> Kleisli IO Pandoc Pandoc

A document transformation, which can depend on BlogLiterately options and can have effects in the IO monad.

xfCond :: BlogLiterately -> Bool

A condition under which to run the transformation.

runTransform :: Transform -> BlogLiterately -> Kleisli IO Pandoc Pandoc

Run a Transform (if its condition is met).

runTransforms :: [Transform] -> BlogLiterately -> Kleisli IO Pandoc Pandoc

Run a pipeline of Transforms.

Standard transforms

These transforms are enabled by default in the standard BlogLiterately executable.

wptexifyXF :: Transform

Format embedded LaTeX for WordPress (if the wplatex flag is set).

ghciXF :: Transform

Format embedded ghci sessions (if the ghci flag is set).

imagesXF :: Transform

Upload embedded local images to the server (if the uploadImages flag is set).

highlightXF :: Transform

Perform syntax highlighting on code blocks.

standardTransforms :: [Transform]

The standard set of transforms that are run by default: wptexifyXF, ghciXF, imagesXF, highlightXF.

Other transforms

These transforms are not enabled by default. To use them, see Text.BlogLiterately.Run.

centerImagesXF :: Transform

Center any images which occur in a paragraph by themselves. Inline images are not affected.

Transforming documents

xformDoc :: BlogLiterately -> [Transform] -> String -> IO String

Transform a complete input document string to an HTML output string, given a list of transformation passes.

Utilities

whenA :: Arrow a => a b b -> Bool -> a b b

Boolean operation for arrows.

Returns its first argument when applied to True, returns returnA when applied to False.

fixLineEndings :: String -> String

Turn CRLF pairs into a single LF. This is necessary since readMarkdown is picky about line endings.