hakyll/src/Hakyll/Core/Metadata.hs

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module Hakyll.Core.Metadata
    ( Metadata
    , MonadMetadata (..)
    , makePatternDependency
    ) where


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import           Control.Monad                  (forM)
import           Data.Map                       (Map)


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import           Hakyll.Core.Dependencies
import           Hakyll.Core.Identifier
import           Hakyll.Core.Identifier.Pattern


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type Metadata = Map String String


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class Monad m => MonadMetadata m where
    getMetadata    :: Identifier -> m Metadata
    getMatches     :: Pattern -> m [Identifier]

    getAllMetadata :: Pattern -> m [(Identifier, Metadata)]
    getAllMetadata pattern = do
        matches' <- getMatches pattern
        forM matches' $ \id' -> do
            metadata <- getMetadata id'
            return (id', metadata)


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makePatternDependency :: MonadMetadata m => Pattern -> m Dependency
makePatternDependency pattern = do
    matches' <- getMatches pattern
    return $ PatternDependency pattern matches'