GHC-8.6 compatibility changes

this is based on 1.4.10, to allow upgrading without using depending
code.

alpheccar#23 contains more comprehensive
upgrades to the latest, never released version of HPDF on github.

Graphics/PDF/Draw.hs

@@ -252,10 +252,10 @@ pdfDictMember k (PDFDictionary d)  = M.member k d
 
 -- | Get a new resource name
 supplyName :: Draw String
-supplyName = do
-    (x:xs) <- gets supplyNames
-    modifyStrict $ \s -> s {supplyNames = xs}
-    return x
+supplyName = 
+    gets supplyNames >>= \(x:xs) -> do
+        modifyStrict $ \s -> s {supplyNames = xs}
+        return x
 
 emptyDrawState :: Int -> DrawState
 emptyDrawState ref = 

Graphics/PDF/LowLevel/Types.hs

@@ -217,7 +217,7 @@ instance PdfObject PDFDictionary where
                                                                     ]
 
           in 
-           M.foldWithKey convertItem mempty a
+           M.foldrWithKey convertItem mempty a
 
 instance PdfLengthInfo PDFDictionary where
 
@@ -295,4 +295,4 @@ modifyStrict f = do
   	put $! (f s)
 
 -- | A monad where paths can be created
-class MonadWriter Builder m => MonadPath m
+class MonadWriter Builder m => MonadPath m

Graphics/PDF/Typesetting/Breaking.hs

@@ -399,7 +399,7 @@ getNewActiveBreakpoints settings sndPass fmaxw actives z =
                                       -- We keep only the best new break
                                       (Map.insertWith updateBreak (position z,line+1,f') (b' {demerit = d',fitnessValue = f', ratio = r}) newbreak ,newmap)
         in
-        let (breaks',actives') = Map.foldWithKey analyzeActive (Map.empty,actives) actives
+        let (breaks',actives') = Map.foldrWithKey analyzeActive (Map.empty,actives) actives
             dmin = minimum . map demerit . Map.elems $ breaks'
             nbreaks = Map.filter (\x -> demerit x < dmin + (fitness_demerit settings)) breaks'
         in
@@ -644,4 +644,4 @@ hyphenPenalty :: BRState
 hyphenPenalty settings s w = FlaggedPenalty w (hyphenPenaltyValue settings) s
 
 kernBox :: s -> PDFFloat -> Letter s
-kernBox s w = Kern w (Just s)
+kernBox s w = Kern w (Just s)