Add haddock documentation to PGF.graphvizDependencyTree and PGF.getDepLabels

They seemed very difficult to use without the documentation, since their
types are not particularly self documenting.

Also documented what the (Bool,Bool) argument to PGF.graphvizAbstractTree
is for.

src/runtime/haskell/PGF/VisualizeTree.hs

@@ -16,10 +16,10 @@ module PGF.VisualizeTree
              , graphvizParseTree
              , graphvizParseTreeDep
              , graphvizDependencyTree
+             , getDepLabels
              , graphvizBracketedString
              , graphvizAlignment
              , gizaAlignment
-             , getDepLabels
              , conlls2latexDoc
              ) where
 
@@ -59,7 +59,9 @@ data GraphvizOptions = GraphvizOptions {noLeaves :: Bool,
 graphvizDefaults = GraphvizOptions False False False True "" "" "" "" "" ""
 
 
--- | Renders abstract syntax tree in Graphviz format
+-- | Renders abstract syntax tree in Graphviz format.
+-- The pair of 'Bool' @(funs,cats)@ lets you control whether function names and
+-- category names are included in the rendered tree.
 graphvizAbstractTree :: PGF -> (Bool,Bool) -> Tree -> String
 graphvizAbstractTree pgf (funs,cats) = render . tree2graph
   where
@@ -113,7 +115,16 @@ graphvizAbstractTree pgf (funs,cats) = render . tree2graph
 
 type Labels = Map.Map CId [String]
 
-graphvizDependencyTree :: String -> Bool -> Maybe Labels -> Maybe String -> PGF -> CId -> Tree -> String
+-- | Visualize word dependency tree.
+graphvizDependencyTree
+  :: String -- ^ Output format: @"latex"@, @"conll"@, @"malt_tab"@, @"malt_input"@ or @"dot"@
+  -> Bool -- ^ Include extra information (debug)
+  -> Maybe Labels -- ^ Label information obtained with 'getDepLabels'
+  -> unused -- ^ not used (was: @Maybe String@)
+  -> PGF
+  -> CId -- ^ The language of analysis
+  -> Tree
+  -> String -- ^ Rendered output in the specified format
 graphvizDependencyTree format debug mlab ms pgf lang t = 
   case format of
     "latex"      -> conll2latex $ render $ vcat (map (hcat . intersperse (char '\t')         ) wnodes)
@@ -217,6 +228,8 @@ graphvizDependencyTree format debug mlab ms pgf lang t =
     root_lbl = "ROOT"
     unspec   = text "_"
 
+-- | Prepare lines obtained from a configuration file for labels for
+-- use with 'graphvizDependencyTree'. Format per line /fun/ /label/@*@.
 getDepLabels :: [String] -> Labels
 getDepLabels ss = Map.fromList [(mkCId f,ls) | f:ls <- map words ss]