Make cacheFonts slightly more useful by passing layer directly to it and run the ReaderT underneath

Hufflepdf.cabal

@@ -78,7 +78,6 @@ executable             getText
                      , bytestring
                      , containers
                      , Hufflepdf
-                     , mtl
                      , text
   ghc-options:         -Wall
   default-language:    Haskell2010

examples/getText.hs

@@ -1,7 +1,6 @@
 {-# LANGUAGE FlexibleContexts #-}
 import Control.Monad ((>=>))
 import Control.Monad.IO.Class (liftIO)
-import Control.Monad.Reader (runReaderT)
 import qualified Data.ByteString.Char8 as BS (readFile)
 import Data.Id (Id(..), mapWithKey)
 import qualified Data.Map as Map (toList)
@@ -34,11 +33,11 @@ displayPage n = withResources (
 getAll :: Layer -> IO ()
 getAll layer =
     Map.toList <$> r Pages layer
-  >>= flip runReaderT layer . cacheFonts . mapM_ (uncurry displayPage)
+  >>= cacheFonts layer . mapM_ (uncurry displayPage)
 
 get :: Int -> Layer -> IO ()
 get n layer =
-  r (P n) layer >>= flip runReaderT layer . cacheFonts . displayPage n
+  r (P n) layer >>= cacheFonts layer . displayPage n
 
 onDoc :: FilePath -> (Layer -> IO ()) -> IO ()
 onDoc inputFile f = do

src/PDF/Pages.hs

@@ -149,8 +149,8 @@ instance Monad m => Box m Contents Page (OrderedMap (Id Object) Content) where
   r Contents = return . contents
   w _ contents page = return $ page {contents}
 
-cacheFonts :: Monad m => StateT CachedFonts m a -> m a
-cacheFonts = flip evalStateT Map.empty
+cacheFonts :: Monad m => Layer -> FontCache m a -> m a
+cacheFonts layer = flip runReaderT layer . flip evalStateT Map.empty
 
 withResources :: Except m => (Page -> ReaderT FontSet m b) -> Page -> FontCache m b
 withResources f p =