Hi, The change in package List-0.4.3 cause hexpat to fail. (It works with List-0.4.2 without "mapMaybe") C. Resolving dependencies... Downloading hexpat-0.20.2... Configuring hexpat-0.20.2... Building hexpat-0.20.2... Preprocessing library hexpat-0.20.2... [ 1 of 12] Compiling Text.XML.Expat.Internal.IO ( Text/XML/Expat/Internal/IO.hs, dist/build/Text/XML/Expat/Internal/IO.o ) [ 2 of 12] Compiling Text.XML.Expat.SAX ( Text/XML/Expat/SAX.hs, dist/build/Text/XML/Expat/SAX.o ) [ 3 of 12] Compiling Text.XML.Expat.Internal.NodeClass ( Text/XML/Expat/Internal/NodeClass.hs, dist/build/Text/XML/Expat/Internal/NodeClass.o ) [ 4 of 12] Compiling Text.XML.Expat.Internal.Qualified ( Text/XML/Expat/Internal/Qualified.hs, dist/build/Text/XML/Expat/Internal/Qualified.o ) [ 5 of 12] Compiling Text.XML.Expat.Internal.Namespaced ( Text/XML/Expat/Internal/Namespaced.hs, dist/build/Text/XML/Expat/Internal/Namespaced.o ) [ 6 of 12] Compiling Text.XML.Expat.Tree ( Text/XML/Expat/Tree.hs, dist/build/Text/XML/Expat/Tree.o ) [ 7 of 12] Compiling Text.XML.Expat.Cursor ( Text/XML/Expat/Cursor.hs, dist/build/Text/XML/Expat/Cursor.o ) [ 8 of 12] Compiling Text.XML.Expat.Internal.DocumentClass ( Text/XML/Expat/Internal/DocumentClass.hs, dist/build/Text/XML/Expat/Internal/DocumentClass.o ) [ 9 of 12] Compiling Text.XML.Expat.Extended ( Text/XML/Expat/Extended.hs, dist/build/Text/XML/Expat/Extended.o ) Text/XML/Expat/Extended.hs:372:25: Ambiguous occurrence `mapMaybe' It could refer to either `Data.List.Class.mapMaybe', imported from `Data.List.Class' at Text/XML/Expat/Extended.hs:83:1-22 or `Data.Maybe.mapMaybe', imported from `Data.Maybe' at Text/XML/Expat/Extended.hs:84:1-17 cabal: Error: some packages failed to install: hexpat-0.20.2 failed during the building phase. The exception was: ExitFailure 1