Introduce pure versions of IO Writers.

Using Text.Pandoc.Free, introduce pure versions of Docx, EPUB, ICML, and
ODT writers. Each of the pure versions is exported along with the IO
version (produced by running `runIO` on the pure reader). Ideally, this
should make the writers easier to test.

1 files changed, 13 insertions, 6 deletions

diff --git a/src/Text/Pandoc/Writers/ICML.hs b/src/Text/Pandoc/Writers/ICML.hs
index e2c123fc2..3a1e772ce 100644
--- a/src/Text/Pandoc/Writers/ICML.hs
+++ b/src/Text/Pandoc/Writers/ICML.hs
@@ -18,7 +18,7 @@ import Text.Pandoc.Definition
 import Text.Pandoc.XML
 import Text.Pandoc.Readers.TeXMath (texMathToInlines)
 import Text.Pandoc.Writers.Shared
-import Text.Pandoc.Shared (linesToPara, splitBy, fetchItem, warn)
+import Text.Pandoc.Shared (linesToPara, splitBy, warn)
 import Text.Pandoc.Options
 import Text.Pandoc.Templates (renderTemplate')
 import Text.Pandoc.Pretty
@@ -28,6 +28,10 @@ import Data.Text as Text (breakOnAll, pack)
 import Control.Monad.State
 import Network.URI (isURI)
 import qualified Data.Set as Set
+import Text.Pandoc.Free (runIO)
+import qualified Text.Pandoc.Free as P
+
+type ICMLAction = P.PandocAction ()
 
 type Style = [String]
 type Hyperlink = [(Int, String)]
@@ -40,7 +44,7 @@ data WriterState = WriterState{
   , maxListDepth :: Int
   }
 
-type WS a = StateT WriterState IO a
+type WS a = StateT WriterState ICMLAction a
 
 defaultWriterState :: WriterState
 defaultWriterState = WriterState{
@@ -121,10 +125,13 @@ subListParName    = "subParagraph"
 footnoteName      = "Footnote"
 citeName          = "Cite"
 
-
 -- | Convert Pandoc document to string in ICML format.
 writeICML :: WriterOptions -> Pandoc -> IO String
-writeICML opts (Pandoc meta blocks) = do
+writeICML opts doc = runIO $ writeICMLPure opts doc
+
+-- | Convert Pandoc document to string in ICML format.
+writeICMLPure :: WriterOptions -> Pandoc -> ICMLAction String
+writeICMLPure opts (Pandoc meta blocks) = do
   let colwidth = if writerWrapText opts == WrapAuto
                     then Just $ writerColumns opts
                     else Nothing
@@ -532,10 +539,10 @@ styleToStrAttr style =
 -- | Assemble an ICML Image.
 imageICML :: WriterOptions -> Style -> Attr -> Target -> WS Doc
 imageICML opts style attr (src, _) = do
-  res  <- liftIO $ fetchItem (writerSourceURL opts) src
+  res  <- lift $ P.fetchItem (writerSourceURL opts) src
   imgS <- case res of
             Left (_) -> do
-              warn $ "Could not find image `" ++ src ++ "', skipping..."
+              lift $ P.warn $ "Could not find image `" ++ src ++ "', skipping..."
               return def
             Right (img, _) -> do
               case imageSize img of