Resolving dependencies...
Configuring mtl-2.2.1...
Configuring syb-0.6...
Building syb-0.6...
Building mtl-2.2.1...
Installed syb-0.6
Installed mtl-2.2.1
Configuring singletons-0.8.1...
Building singletons-0.8.1...
Failed to install singletons-0.8.1
Build log ( /home/builder/.cabal/logs/singletons-0.8.1.log ):
cabal: Entering directory '/tmp/cabal-tmp-4957/singletons-0.8.1'
Configuring singletons-0.8.1...
Building singletons-0.8.1...
Preprocessing library singletons-0.8.1...
[1 of 6] Compiling Singletons.Util  ( Singletons/Util.hs, dist/build/Singletons/Util.o )

Singletons/Util.hs:55:35: warning: [-Wincomplete-patterns]
    Pattern match(es) are non-exhaustive
    In a case alternative:
        Patterns not matched:
            (GadtC _ _ _)
            (RecGadtC _ _ _)
[2 of 6] Compiling Singletons.Promote ( Singletons/Promote.hs, dist/build/Singletons/Promote.o )

Singletons/Promote.hs:143:29: error:
    Not in scope: data constructor ‘FamilyD’
    Perhaps you meant ‘FamilyI’ (imported from Language.Haskell.TH)

Singletons/Promote.hs:265:18: error:
    Not in scope: data constructor ‘FamilyD’
    Perhaps you meant ‘FamilyI’ (imported from Language.Haskell.TH)
cabal: Leaving directory '/tmp/cabal-tmp-4957/singletons-0.8.1'
cabal: Error: some packages failed to install:
singletons-0.8.1 failed during the building phase. The exception was:
ExitFailure 1