5 files changed, 9 insertions, 1 deletions
diff --git a/src/runtime/haskell/Data/Binary/Builder.hs b/src/runtime/haskell/Data/Binary/Builder.hs
index 03531daa7..b69371f0e 100644
--- a/src/runtime/haskell/Data/Binary/Builder.hs
+++ b/src/runtime/haskell/Data/Binary/Builder.hs
@@ -100,6 +100,11 @@ newtype Builder = Builder {
         runBuilder :: (Buffer -> [S.ByteString]) -> Buffer -> [S.ByteString]
     }
 
+#if MIN_VERSION_base(4,11,0)
+instance Semigroup Builder where
+  (<>) = append
+#endif
+
 instance Monoid Builder where
     mempty  = empty
     {-# INLINE mempty #-}
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/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/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