Resolving dependencies... Configuring random-1.1... Configuring mtl-2.2.1... Building random-1.1... Building mtl-2.2.1... Installed random-1.1 Installed mtl-2.2.1 Configuring operational-0.2.3.5... Building operational-0.2.3.5... Installed operational-0.2.3.5 Configuring Etage-0.1.6... Building Etage-0.1.6... Failed to install Etage-0.1.6 Build log ( /home/builder/.cabal/logs/Etage-0.1.6.log ): cabal: Entering directory '/tmp/cabal-tmp-31540/Etage-0.1.6' Configuring Etage-0.1.6... Building Etage-0.1.6... Preprocessing library Etage-0.1.6... lib/Control/Etage/Externals.hs:1:58: warning: -XOverlappingInstances is deprecated: instead use per-instance pragmas OVERLAPPING/OVERLAPPABLE/OVERLAPS [ 1 of 14] Compiling Control.Etage.Chan ( lib/Control/Etage/Chan.hs, dist/build/Control/Etage/Chan.o ) lib/Control/Etage/Chan.hs:131:13: error: Ambiguous occurrence ‘tryReadMVar’ It could refer to either ‘Control.Concurrent.MVar.tryReadMVar’, imported from ‘Control.Concurrent.MVar’ at lib/Control/Etage/Chan.hs:41:1-30 (and originally defined in ‘GHC.MVar’) or ‘Control.Etage.Chan.tryReadMVar’, defined at lib/Control/Etage/Chan.hs:101:1 cabal: Leaving directory '/tmp/cabal-tmp-31540/Etage-0.1.6' cabal: Error: some packages failed to install: Etage-0.1.6 failed during the building phase. The exception was: ExitFailure 1