Resolving dependencies...
Downloading data-category-0.3.1...
Configuring data-category-0.3.1...
Building data-category-0.3.1...
Preprocessing library data-category-0.3.1...
[ 1 of 17] Compiling Data.Category    ( Data/Category.hs, dist/build/Data/Category.o )

Data/Category.hs:30:10:
    Unexpected type `~>' where type variable expected
    In the declaration of `Obj ~> a'
Failed to install data-category-0.3.1
cabal: Error: some packages failed to install:
data-category-0.3.1 failed during the building phase. The exception was:
ExitFailure 1