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|
-- | A Module that allows easy rendering of RSS feeds. If you use this module,
-- you must make sure you set the `absoluteUrl` field in the main Hakyll
-- configuration.
--
-- Apart from that, the main rendering functions (@renderRss@,
-- @renderRssWith@, @renderAtom@ all @renderAtomWith@) all assume that you
-- pass the list of @Renderable@s so that the most recent entry in the feed is
-- the first item in the list.
--
-- Also note that the @Renderable@s should have (at least) the following
-- fields to produce a correct feed:
--
-- - @$title@: Title of the item.
--
-- - @$description@: Description to appear in the feed.
--
-- - @$url@: URL to the item - this is usually set automatically.
--
-- Furthermore, the feed will not validate if an empty list is passed.
module Text.Hakyll.Feed
( FeedConfiguration (..)
, renderRss
, renderRssWith
, renderAtom
, renderAtomWith
) where
import Control.Arrow ((>>>), second)
import Control.Monad.Reader (liftIO)
import Data.Maybe (fromMaybe)
import qualified Data.Map as M
import Text.Hakyll.Context (ContextManipulation, renderDate)
import Text.Hakyll.Hakyll (Hakyll)
import Text.Hakyll.Render (render, renderChain)
import Text.Hakyll.Renderables (createListingWith)
import Text.Hakyll.RenderAction
import Paths_hakyll
-- | This is a data structure to keep the configuration of a feed.
data FeedConfiguration = FeedConfiguration
{ -- | Url of the feed (relative to site root). For example, @rss.xml@.
feedUrl :: String
, -- | Title of the feed.
feedTitle :: String
, -- | Description of the feed.
feedDescription :: String
, -- | Name of the feed author.
feedAuthorName :: String
}
-- | This is an auxiliary function to create a listing that is, in fact, a feed.
-- The items should be sorted on date.
createFeedWith :: ContextManipulation -- ^ Manipulation to apply on the items.
-> FeedConfiguration -- ^ Feed configuration.
-> [Renderable] -- ^ Items to include.
-> FilePath -- ^ Feed template.
-> FilePath -- ^ Item template.
-> Renderable
createFeedWith manipulation configuration renderables template itemTemplate =
listing >>> render template
where
listing = createListingWith manipulation (feedUrl configuration)
[itemTemplate] renderables additional
additional = map (second $ Left . ($ configuration))
[ ("title", feedTitle)
, ("description", feedDescription)
, ("authorName", feedAuthorName)
] ++ updated
-- Take the first timestamp, which should be the most recent.
updated = let action = createRenderAction $
return . fromMaybe "foo" . M.lookup "timestamp"
manip = createManipulationAction manipulation
toTuple r = ("timestamp", Right $ r >>> manip >>> action)
in map toTuple $ take 1 renderables
-- | Abstract function to render any feed.
renderFeedWith :: ContextManipulation -- ^ Manipulation to apply on the items.
-> FeedConfiguration -- ^ Feed configuration.
-> [Renderable] -- ^ Items to include in the feed.
-> FilePath -- ^ Feed template.
-> FilePath -- ^ Item template.
-> Hakyll ()
renderFeedWith manipulation configuration renderables template itemTemplate = do
template' <- liftIO $ getDataFileName template
itemTemplate' <- liftIO $ getDataFileName itemTemplate
let renderFeedWith' = createFeedWith manipulation configuration
renderables template' itemTemplate'
renderChain [] renderFeedWith'
-- | Render an RSS feed with a number of items.
renderRss :: FeedConfiguration -- ^ Feed configuration.
-> [Renderable] -- ^ Items to include in the RSS feed.
-> Hakyll ()
renderRss = renderRssWith id
-- | Render an RSS feed with a number of items. This function allows you to
-- specify a @ContextManipulation@ which will be applied on every
-- @Renderable@. Note that the given @Renderable@s should be sorted so the
-- most recent one is first.
renderRssWith :: ContextManipulation -- ^ Manipulation to apply on the items.
-> FeedConfiguration -- ^ Feed configuration.
-> [Renderable] -- ^ Items to include in the feed.
-> Hakyll ()
renderRssWith manipulation configuration renderables =
renderFeedWith manipulation' configuration renderables
"templates/rss.xml" "templates/rss-item.xml"
where
manipulation' = manipulation . renderRssDate
-- | @ContextManipulation@ that renders a date to RSS format.
renderRssDate :: ContextManipulation
renderRssDate = renderDate "timestamp" "%a, %d %b %Y %H:%M:%S UT"
"No date found."
-- | Render an Atom feed with a number of items.
renderAtom :: FeedConfiguration
-> [Renderable]
-> Hakyll ()
renderAtom = renderAtomWith id
-- | A version of @renderAtom@ that allows you to specify a manipulation to
-- apply on the @Renderable@s.
renderAtomWith :: ContextManipulation -- ^ Manipulation to apply on the items.
-> FeedConfiguration -- ^ Feed configuration.
-> [Renderable] -- ^ Items to include in the feed.
-> Hakyll ()
renderAtomWith manipulation configuration renderables =
renderFeedWith manipulation' configuration renderables
"templates/atom.xml" "templates/atom-item.xml"
where
manipulation' = manipulation . renderAtomDate
-- | Render a date to Atom format.
renderAtomDate :: ContextManipulation
renderAtomDate = renderDate "timestamp" "%Y-%m-%dT%H:%M:%SZ" "No date found."
|
