Change RunPandoc to be more file-centric

byg/src/DependencyGenerator.hs

@@ -110,5 +110,5 @@ convertImage = runFunctionIO ConvertImage
 saveFile :: Token (String, FilePath) -> DepGenM ()
 saveFile = runFunctionIO SaveFile
 
-runPandoc :: Token String -> DepGenM String
+runPandoc :: Token (FilePath, FilePath) -> DepGenM ()
 runPandoc = runFunctionIO RunPandoc

byg/src/Evaluation/FunctionIO.hs

@@ -18,8 +18,8 @@ evalFunctionIO f x = case (f, x) of
   (SaveFile, Tuple (String _, String _)) ->
     pure $ Empty
 
-  (RunPandoc, String _) ->
+  (RunPandoc, Tuple (String _, String _)) ->
-    pure $ String undefined
+    pure $ Empty
 
   _ ->
     error "unexpected combination of function and argument type"