Resolving dependencies...
Downloading data-category-0.0.2...
Configuring data-category-0.0.2...
Building data-category-0.0.2...
Preprocessing library data-category-0.0.2...
[1 of 9] Compiling Data.Category    ( Data/Category.hs, dist/build/Data/Category.o )

Data/Category.hs:8:17:
    Unexpected type `~>' where type variable expected
    In the declaration of `CategoryO ~> a'
Failed to install data-category-0.0.2
cabal: Error: some packages failed to install:
data-category-0.0.2 failed during the building phase. The exception was:
ExitFailure 1