Convert all writers to use PandocMonad.

Since PandocMonad is an instance of MonadError, this will allow us, in a
future commit, to change all invocations of `error` to `throwError`,
which will be preferable for the pure versions. At the moment, we're
disabling the lua custom writers (this is temporary).

This requires changing the type of the Writer in Text.Pandoc. Right now,
we run `runIOorExplode` in pandoc.hs, to make the conversion easier. We
can switch it to the safer `runIO` in the future.

Note that this required a change to Text.Pandoc.PDF as well. Since
running an external program is necessarily IO, we can be clearer about
using PandocIO.

1 files changed, 3 insertions, 2 deletions

diff --git a/src/Text/Pandoc/Writers/ZimWiki.hs b/src/Text/Pandoc/Writers/ZimWiki.hs
index 56a5d5455..f15b290e4 100644
--- a/src/Text/Pandoc/Writers/ZimWiki.hs
+++ b/src/Text/Pandoc/Writers/ZimWiki.hs
@@ -45,6 +45,7 @@ import Network.URI ( isURI )
 import Control.Monad ( zipWithM )
 import Control.Monad.State ( modify, State, get, evalState )
 --import Control.Monad.Reader ( ReaderT, runReaderT, ask, local )
+import Text.Pandoc.Class ( PandocMonad )
 
 data WriterState = WriterState {
     stItemNum   :: Int,
@@ -55,8 +56,8 @@ instance Default WriterState where
   def = WriterState { stItemNum = 1, stIndent = "" }
 
 -- | Convert Pandoc to ZimWiki.
-writeZimWiki :: WriterOptions -> Pandoc -> String
-writeZimWiki opts document = evalState (pandocToZimWiki opts document) (WriterState 1 "")
+writeZimWiki :: PandocMonad m => WriterOptions -> Pandoc -> m String
+writeZimWiki opts document = return $ evalState (pandocToZimWiki opts document) (WriterState 1 "")
 
 -- | Return ZimWiki representation of document.
 pandocToZimWiki :: WriterOptions -> Pandoc -> State WriterState String