Split pandoc handling into reading and writing steps

byg/src/Functions/Pandoc.hs

@@ -1,24 +1,35 @@
 module Functions.Pandoc
-  ( runPandoc
+  ( readMarkdown
+  , writeHtml
   ) where
 
 import Types (IsFunction(..), Token)
 import DependencyGenerator (DepGenM, TokenableTo(..), runFunction)
 
 import Data.Text (Text)
-import qualified Data.Text.Lazy as TL
+import Text.Pandoc.Definition (Pandoc)
 import qualified Text.Pandoc as P
-import qualified Text.Blaze.Html.Renderer.Text as B
 
+runPandoc :: P.PandocPure a -> a
+runPandoc m = case P.runPure m of
+  Left e -> error ("unexpected pandoc error: " ++ show e)
+  Right result -> result
 
-data RunPandoc = RunPandoc deriving Show
-instance IsFunction RunPandoc Text Text where
-  evalFunction RunPandoc contents =
+data ReadMarkdown = ReadMarkdown deriving Show
+instance IsFunction ReadMarkdown Text Pandoc where
+  evalFunction ReadMarkdown contents =
     let settings = P.def { P.readerExtensions = P.extensionsFromList [ P.Ext_raw_html ] }
-        m = P.writeHtml5 P.def =<< P.readMarkdown settings contents
-    in case P.runPure m of
-         Left e -> error ("unexpected pandoc error: " ++ show e)
-         Right html -> TL.toStrict $ B.renderHtml html
+    in runPandoc $ P.readMarkdown settings contents
 
-runPandoc :: TokenableTo Text a => a -> DepGenM (Token Text)
-runPandoc a = runFunction RunPandoc =<< toToken a
+readMarkdown :: TokenableTo Text a => a -> DepGenM (Token Pandoc)
+readMarkdown a = runFunction ReadMarkdown =<< toToken a
+
+
+data WriteHtml = WriteHtml deriving Show
+instance IsFunction WriteHtml Pandoc Text where
+  evalFunction WriteHtml pandoc =
+    runPandoc
+    $ P.writeHtml5String P.def pandoc
+
+writeHtml :: TokenableTo Pandoc a => a -> DepGenM (Token Text)
+writeHtml a = runFunction WriteHtml =<< toToken a