* [constructions](constructions.lean) : constructions of basic examples and constructions of categories: opposite, type, discrete, product, functor, slice and arrow categories
The following files hardly have any content so far.
* [limit](limit.lean) : limits and colimits
* [adjoint](adjoint.lean) : adjoint functors
* [yoneda](yoneda.lean) : Yoneda embedding and Yoneda lemma