6 files changed, 19 insertions, 15 deletions
diff --git a/src/runtime/haskell/PGF/ByteCode.hs b/src/runtime/haskell/PGF/ByteCode.hs
index 579d6b3bb..ef21ab229 100644
--- a/src/runtime/haskell/PGF/ByteCode.hs
+++ b/src/runtime/haskell/PGF/ByteCode.hs
@@ -2,7 +2,7 @@ module PGF.ByteCode(Literal(..),
                     CodeLabel, Instr(..), IVal(..), TailInfo(..),
                     ppLit, ppCode, ppInstr
                    ) where
-
+import Prelude hiding ((<>)) -- GHC 8.4.1 clash with Text.PrettyPrint
 import PGF.CId
 import Text.PrettyPrint
 
diff --git a/src/runtime/haskell/PGF/Expr.hs b/src/runtime/haskell/PGF/Expr.hs
index 331a69d90..d015f18e0 100644
--- a/src/runtime/haskell/PGF/Expr.hs
+++ b/src/runtime/haskell/PGF/Expr.hs
@@ -2,7 +2,7 @@ module PGF.Expr(Tree, BindType(..), Expr(..), Literal(..), Patt(..), Equation(..
                 readExpr, showExpr, pExpr, pBinds, ppExpr, ppPatt, pattScope,
 
                 mkAbs,    unAbs,
-                mkApp,    unApp, unAppForm,
+                mkApp,    unApp, unapply,
                 mkStr,    unStr,
                 mkInt,    unInt,
                 mkDouble, unDouble,
@@ -108,13 +108,13 @@ mkApp f es = foldl EApp (EFun f) es
 
 -- | Decomposes an expression into application of function
 unApp :: Expr -> Maybe (CId,[Expr])
-unApp e = case unAppForm e of
+unApp e = case unapply e of
   (EFun f,es) -> Just (f,es)
   _           -> Nothing
 
 -- | Decomposes an expression into an application of a constructor such as a constant or a metavariable
-unAppForm :: Expr -> (Expr,[Expr])
-unAppForm = extract []
+unapply :: Expr -> (Expr,[Expr])
+unapply = extract []
   where
     extract es f@(EFun _)   = (f,es)
     extract es (EApp e1 e2) = extract (e2:es) e1
diff --git a/src/runtime/haskell/PGF/Macros.hs b/src/runtime/haskell/PGF/Macros.hs
index de175616c..3fc7a5804 100644
--- a/src/runtime/haskell/PGF/Macros.hs
+++ b/src/runtime/haskell/PGF/Macros.hs
@@ -1,4 +1,5 @@
 module PGF.Macros where
+import Prelude hiding ((<>)) -- GHC 8.4.1 clash with Text.PrettyPrint
 
 import PGF.CId
 import PGF.Data
diff --git a/src/runtime/haskell/PGF/Optimize.hs b/src/runtime/haskell/PGF/Optimize.hs
index 8739c8665..6e7f51fb2 100644
--- a/src/runtime/haskell/PGF/Optimize.hs
+++ b/src/runtime/haskell/PGF/Optimize.hs
@@ -21,6 +21,7 @@ import qualified Data.IntMap as IntMap
 import qualified PGF.TrieMap as TrieMap
 import qualified Data.List as List
 import Control.Monad.ST
+import Debug.Trace
 
 optimizePGF :: PGF -> PGF
 optimizePGF pgf = pgf{concretes=fmap (updateConcrete (abstract pgf) . 
@@ -178,26 +179,26 @@ topDownFilter startCat cnc =
 
 
 bottomUpFilter :: Concr -> Concr
-bottomUpFilter cnc = cnc{productions=filterProductions IntMap.empty IntSet.empty (productions cnc)}
+bottomUpFilter cnc = cnc{productions=filterProductions IntMap.empty (productions cnc)}
 
-filterProductions prods0 hoc0 prods
+filterProductions prods0 prods
   | prods0 == prods1 = prods0
-  | otherwise        = filterProductions prods1 hoc1 prods
+  | otherwise        = filterProductions prods1 prods
   where
-    (prods1,hoc1) = IntMap.foldWithKey foldProdSet (IntMap.empty,IntSet.empty) prods
+    prods1 = IntMap.foldWithKey foldProdSet IntMap.empty prods
+    hoc    = IntMap.fold (\set !hoc -> Set.fold accumHOC hoc set) IntSet.empty prods
 
-    foldProdSet fid set (!prods,!hoc)
-      | Set.null set1 = (prods,hoc)
-      | otherwise     = (IntMap.insert fid set1 prods,hoc1)
+    foldProdSet fid set !prods
+      | Set.null set1 = prods
+      | otherwise     = IntMap.insert fid set1 prods
       where
         set1 = Set.filter filterRule set
-        hoc1 = Set.fold accumHOC hoc set1
 
     filterRule (PApply funid args) = all (\(PArg _ fid) -> isLive fid) args
     filterRule (PCoerce fid)       = isLive fid
     filterRule _                   = True
 
-    isLive fid = isPredefFId fid || IntMap.member fid prods0 || IntSet.member fid hoc0
+    isLive fid = isPredefFId fid || IntMap.member fid prods0 || IntSet.member fid hoc
 
     accumHOC (PApply funid args) hoc = List.foldl' (\hoc (PArg hypos _) -> List.foldl' (\hoc (_,fid) -> IntSet.insert fid hoc) hoc hypos) hoc args
     accumHOC _                   hoc = hoc
@@ -241,7 +242,7 @@ splitLexicalRules cnc p_prods =
         seq2prefix (SymALL_CAPIT    :syms) = TrieMap.fromList [wf ["&|"]]
 
 updateConcrete abs cnc = 
-  let p_prods0      = filterProductions IntMap.empty IntSet.empty (productions cnc)
+  let p_prods0      = filterProductions IntMap.empty (productions cnc)
       (lex,p_prods) = splitLexicalRules cnc p_prods0
       l_prods       = linIndex cnc p_prods0
   in cnc{pproductions = p_prods, lproductions = l_prods, lexicon = lex}
diff --git a/src/runtime/haskell/PGF/Printer.hs b/src/runtime/haskell/PGF/Printer.hs
index 43c270b13..07e94f866 100644
--- a/src/runtime/haskell/PGF/Printer.hs
+++ b/src/runtime/haskell/PGF/Printer.hs
@@ -1,5 +1,6 @@
 {-# LANGUAGE FlexibleContexts #-}
 module PGF.Printer (ppPGF,ppCat,ppFId,ppFunId,ppSeqId,ppSeq,ppFun) where
+import Prelude hiding ((<>)) -- GHC 8.4.1 clash with Text.PrettyPrint
 
 import PGF.CId
 import PGF.Data
diff --git a/src/runtime/haskell/PGF/VisualizeTree.hs b/src/runtime/haskell/PGF/VisualizeTree.hs
index 5d884fafe..520eb59c3 100644
--- a/src/runtime/haskell/PGF/VisualizeTree.hs
+++ b/src/runtime/haskell/PGF/VisualizeTree.hs
@@ -23,6 +23,7 @@ module PGF.VisualizeTree
              , gizaAlignment
              , conlls2latexDoc
              ) where
+import Prelude hiding ((<>)) -- GHC 8.4.1 clash with Text.PrettyPrint
 
 import PGF.CId (wildCId,showCId,ppCId,mkCId) --CId,pCId,
 import PGF.Data