Text.Pandoc.Filter.Utils

This module contains some utility functions to work with different levels of Pandoc filters. For example, for the conversion from Inline -> [Inline] to Pandoc -> Pandoc filter.

If you don't need to compose filters and only want to convert between Pandoc filter functions, just use convertFilter and convertFilterM.

However, if you are working with multiple Pandoc filters of different type and want to compose them, this module also provides a monoid wrapper type PartialFilterM, which I call a "wrapped filter", and a few functions to apply, compose, and convert them.

Filter function conversion

convertFilter

Arguments

:: ToPartialFilter Identity f p

=> f

A filter function.

-> p -> p

Filter function acting on p.

Conversion between filter functions, e.g. from Inline -> [Inline] filter to Pandoc -> Pandoc filter.

convertFilterM

Arguments

:: (Monad m, ToPartialFilter m f p)

=> f

A monadic filter function.

-> p -> m p

Monadic filter function acting on p.

Conversion between monadic filter functions, e.g. from Inline -> IO [Inline] filter to Pandoc -> IO Pandoc filter.

Wrapped filter definitions

type PartialFilter = PartialFilterM Identity

PartialFilter p is a wrapper for ordinary p -> p Pandoc filters acting on a subnode (e.g. Inline or Block) of the Pandoc abstract syntax tree. On this page, we will call it a "wrapped" filter to distinguish it from filter functions a -> b.

• p: the type of a subnode of Pandoc (e.g. Inline).

type PandocFilter = PartialFilter Pandoc

An alias for PartialFilter Pandoc. It encapsulates a monadic filter Pandoc -> m Pandoc acting directly on Pandoc.

• m: a monad.

data PartialFilterM m p

PartialFilterM m p is a wrapper for any monadic p -> m p Pandoc filters acting on a subnode (e.g. Inline or Block) of the Pandoc abstract syntax tree. On this page, we will call it a "wrapped" filter to distinguish it from filter functions a -> m b.

• m: a monad.
• p: the type of a subnode of Pandoc (e.g. Inline).

Instances

(Monad m, Walkable a b) => ToPartialFilter m (PartialFilterM m a) b

This instance can be used to convert PartialFilterM m a to PartialFilterM m b.

Defined in Text.Pandoc.Filter.Utils

Methods

mkFilter :: PartialFilterM m a -> PartialFilterM m b

Monad m => Semigroup (PartialFilterM m p)

The Semigroup instance of PartialFilterM. f1 <> f2 will apply f1 first followed by f2.

Defined in Text.Pandoc.Filter.Utils

Methods

(<>) :: PartialFilterM m p -> PartialFilterM m p -> PartialFilterM m p

sconcat :: NonEmpty (PartialFilterM m p) -> PartialFilterM m p

stimes :: Integral b => b -> PartialFilterM m p -> PartialFilterM m p

Monad m => Monoid (PartialFilterM m p)

The Monoid instance of PartialFilterM.

Defined in Text.Pandoc.Filter.Utils

Methods

mempty :: PartialFilterM m p

mappend :: PartialFilterM m p -> PartialFilterM m p -> PartialFilterM m p

mconcat :: [PartialFilterM m p] -> PartialFilterM m p

type PandocFilterM m = PartialFilterM m Pandoc

An alias for PartialFilterM m Pandoc, a monadic version of PandocFilter.

• m: a monad.

Filter function → Wrapped filter

class ToPartialFilter m f p where

A helper typeclass used as a polymorphic constructor of PartialFilterM.

Methods

mkFilter

Arguments

:: f

A filter function, usually a -> a for some Walkable a p.

-> PartialFilterM m p

Wrapped Pandoc filter.

The actual constructor of PartialFilterM. It takes an ordinary filter function a -> b and wraps it as a wrapped filter PartialFilterM. It can also be used to convert between different types of PartialFilterM m.

Instances

(Monad m, Walkable a b) => ToPartialFilter m (PartialFilterM m a) b

This instance can be used to convert PartialFilterM m a to PartialFilterM m b.

Defined in Text.Pandoc.Filter.Utils

Methods

mkFilter :: PartialFilterM m a -> PartialFilterM m b

(Monad m, Walkable [a] p) => ToPartialFilter m (a -> m [a]) p

Defined in Text.Pandoc.Filter.Utils

Methods

mkFilter :: (a -> m [a]) -> PartialFilterM m p

(Monad m, Walkable [a] p) => ToPartialFilter m (a -> [a]) p

Defined in Text.Pandoc.Filter.Utils

Methods

mkFilter :: (a -> [a]) -> PartialFilterM m p

(Monad m, Walkable a p) => ToPartialFilter m (a -> m a) p

Defined in Text.Pandoc.Filter.Utils

Methods

mkFilter :: (a -> m a) -> PartialFilterM m p

(Monad m, Walkable a p) => ToPartialFilter m (a -> a) p

Defined in Text.Pandoc.Filter.Utils

Methods

mkFilter :: (a -> a) -> PartialFilterM m p

mkConcatedFilter

Arguments

:: (Monad m, ToPartialFilter m f p, Foldable t)

=> t f

A list of filter functions of the same type.

-> PartialFilterM m p

Concatenated filter.

Construct a wrapped filter PartialFilterM from a list of filter functions of the same type. The final filter is concatenated from left to right such that the first element in the list will be applied first and the last element will be applied at the end.

For example, it can be used to convert an list of filter functions [Inline -> [Inline]] to a wrapped filter PandocFilter.

Wrapped filter application/composition

applyFilter

Arguments

:: PartialFilter p

A wrapped filter.

-> p

Pandoc AST node.

-> p

Transformed node.

Apply a wrapped filter to p, which returns p directly.

sequenceFilters

Arguments

:: Foldable t

=> t (PartialFilter p)

A list of wrapped filter.

-> p

Pandoc AST node.

-> p

Transformed node.

Apply a list of wrapped filters sequentially, from left to right, i.e. the first element in the list will be applied first and the last element will be applied at the end.

applyFilterM :: PartialFilterM m p -> p -> m p

Apply a monadic filter to p.

sequenceFiltersM

Arguments

:: (Foldable t, Monad m)

=> t (PartialFilterM m p)

A list of monadic wrapped filters.

-> p

Pandoc AST node.

-> m p

Transformed node.

Apply a list of monadic wrapped filters sequentially, from left to right, i.e. the first element in the list will be applied first and the last element will be applied at the end.

Function aliases

applyFilters

Arguments

:: Foldable t

=> t (PartialFilter p)

A list of wrapped filter.

-> p

Pandoc AST node.

-> p

Transformed node.

The same as sequenceFilters, but this function will conflict with a function with the same name in Pandoc, and thus not exported in Text.Pandoc.Utils, but it can be used by importing this module.

applyFiltersM

Arguments

:: (Foldable t, Monad m)

=> t (PartialFilterM m p)

A list of monadic wrapped filters.

-> p

Pandoc AST node.

-> m p

Transformed node.

The same as sequenceFiltersM, but it is not exported in Text.Pandoc.Utils to avoid naming conflicts. It can be used by importing this module.

Wrapped filter → filter function

getFilter

Arguments

:: Walkable a b

=> PartialFilter a

A wrapped partial filter on a.

-> b -> b

Filter function that can be directly applied to b.

It is mostly the same as applyFilter, which converts a wrapped filter to a filter function, but it should be used when you don't need to apply the filter immediately. There is a slight difference in that it will perform an implicit conversion if the requested filter function is of a different type.

For example, it can be used to convert a wrapped filter PartialFilter Inline to filter function Block -> Block.

getConcatedFilter

Arguments

:: (Foldable t, Walkable a b)

=> t (PartialFilter a)

A list of wrapped filter acting on a

-> b -> b

Filter function applicable to b directly.

It is mostly the same as applyFilters, which converts a list of wrapped filter to a filter function, but it should be used when you don't need to apply the filter immediately. There is a slight difference in that it will perform an implicit conversion if the requested filter function is of a different type.

For example, it can be used to convert a list of wrapped filter [PartialFilter Inline] to a filter function Block -> Block.

getFilterM

Arguments

:: (Monad m, Walkable a b)

=> PartialFilterM m a

A wrapped filter on a.

-> b -> m b

Filter function that can be directly applied to b.

It is mostly the same as applyFilterM, which converts a wrapped monadic filter to a monadic filter function, but it should be used when you don't need to apply the filter immediately. There is a slight difference in that it will perform an implicit conversion if the requested filter function is of a different type.

For example, it can be used to convert a wrapped monadic filter PartialFilterM IO Inline to monadic filter function Block -> IO Block.

getConcatedFilterM

Arguments

:: (Foldable t, Monad m, Walkable a b)

=> t (PartialFilterM m a)

A list of monadic partial filters on a.

-> b -> m b

Monadic filter function applicable to b directly.

It is mostly the same as applyFiltersM, which converts a list of wrapped monadic filter to a monadic filter function, but it should be used when you don't need to apply the filter immediately. There is a slight difference in that it will perform an implicit conversion if the requested filter function is of a different type.

For example, it can be used to convert a list of wrapped monadic filter [PartialFilterM IO Inline] to a filter function Block -> IO Block.

Wrapped filter conversion

toFilterM

Arguments

:: Monad m

=> PartialFilter p

An ordinary filter.

-> PartialFilterM m p

The monadic version.

Convert an ordinary wrapped filter PartialFilter to the monadic version PartialFilterM.

For example, it can be used to convert an ordinary wrapped filter PartialFilter Inline to monadic wrapped filter PartialFilterM IO Inline.