Resolving dependencies...
Configuring data-category-0.0.3...
Building data-category-0.0.3...
Preprocessing library data-category-0.0.3...
[ 1 of 10] Compiling Data.Category    ( Data/Category.hs, dist/build/Data/Category.o )

Data/Category.hs:39:17:
    Unexpected type ‘(~>)’
    In the class declaration for ‘CategoryO’
    A class declaration should have form
      class CategoryO a b where ...
Failed to install data-category-0.0.3
cabal: Error: some packages failed to install:
data-category-0.0.3 failed during the building phase. The exception was:
ExitFailure 1