Resolving dependencies...
Configuring exceptional-0.1.2.0...
Building exceptional-0.1.2.0...
Failed to install exceptional-0.1.2.0
Build log ( /home/builder/.cabal/logs/exceptional-0.1.2.0.log ):
cabal: Entering directory '/tmp/cabal-tmp-10324/exceptional-0.1.2.0'
Configuring exceptional-0.1.2.0...
Building exceptional-0.1.2.0...
Preprocessing library exceptional-0.1.2.0...
[1 of 1] Compiling Control.Exceptional ( Control/Exceptional.hs, dist/build/Control/Exceptional.o )

Control/Exceptional.hs:45:24: error:
    • Couldn't match expected type ‘Either String a’
                  with actual type ‘Exceptional a’
    • In the expression: Success x
      In an equation for ‘toEither’: toEither (Success x) = Success x
    • Relevant bindings include
        x :: a (bound at Control/Exceptional.hs:45:19)
        toEither :: Exceptional a -> Either String a
          (bound at Control/Exceptional.hs:44:1)
cabal: Leaving directory '/tmp/cabal-tmp-10324/exceptional-0.1.2.0'
cabal: Error: some packages failed to install:
exceptional-0.1.2.0 failed during the building phase. The exception was:
ExitFailure 1