Resolving dependencies... Starting dual-0.1.1.1 Starting tagged-0.8.6 Building dual-0.1.1.1 Building tagged-0.8.6 Completed dual-0.1.1.1 Completed tagged-0.8.6 Starting hs-functors-0.1.7.0 Building hs-functors-0.1.7.0 Completed hs-functors-0.1.7.0 Downloading hs-ix-0.2.0.0 Downloaded hs-ix-0.2.0.0 Starting hs-ix-0.2.0.0 Building hs-ix-0.2.0.0 Failed to install hs-ix-0.2.0.0 Build log ( /home/builder/.cabal/logs/ghc-8.6.3/hs-ix-0.2.0.0-7xLRuK3hOnX1oJuM56pAIe.log ): cabal: Entering directory '/tmp/cabal-tmp-25869/hs-ix-0.2.0.0' Configuring hs-ix-0.2.0.0... Preprocessing library for hs-ix-0.2.0.0.. Building library for hs-ix-0.2.0.0.. [1 of 8] Compiling Control.Monad.Indexed.Signatures ( Control/Monad/Indexed/Signatures.hs, dist/build/Control/Monad/Indexed/Signatures.o ) [2 of 8] Compiling Data.Functor.Indexed ( Data/Functor/Indexed.hs, dist/build/Data/Functor/Indexed.o ) Data/Functor/Indexed.hs:9:1: warning: [-Wunused-imports] The import of ‘Eq, Foldable, Ord, Traversable’ from module ‘Prelude’ is redundant | 9 | import Prelude (Functor (fmap), pure, (<$>), Foldable, Traversable, Eq, Ord) | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ [3 of 8] Compiling Control.Monad.Indexed.Trans.Writer ( Control/Monad/Indexed/Trans/Writer.hs, dist/build/Control/Monad/Indexed/Trans/Writer.o ) [4 of 8] Compiling Control.Monad.Indexed.Trans.State ( Control/Monad/Indexed/Trans/State.hs, dist/build/Control/Monad/Indexed/Trans/State.o ) [5 of 8] Compiling Control.Monad.Indexed.Trans.Cont ( Control/Monad/Indexed/Trans/Cont.hs, dist/build/Control/Monad/Indexed/Trans/Cont.o ) Control/Monad/Indexed/Trans/Cont.hs:59:27: error: Ambiguous occurrence ‘Base.fail’ It could refer to either ‘Base.fail’, imported qualified from ‘Control.Monad’ at Control/Monad/Indexed/Trans/Cont.hs:9:1-38 (and originally defined in ‘GHC.Base’) or ‘Base.fail’, imported qualified from ‘Control.Monad.Fail’ at Control/Monad/Indexed/Trans/Cont.hs:10:1-43 | 59 | fail = ContT . pure . Base.fail | ^^^^^^^^^ cabal: Leaving directory '/tmp/cabal-tmp-25869/hs-ix-0.2.0.0' cabal: Error: some packages failed to install: hs-ix-0.2.0.0-7xLRuK3hOnX1oJuM56pAIe failed during the building phase. The exception was: ExitFailure 1