|Portability||non-portable (GHC Extensions)|
|Maintainer||Tom Hvitved <email@example.com>|
This module defines higher-order difunctors, a hybrid between higher-order functors (Johann, Ghani, POPL '08), and difunctors (Meijer, Hutton, FPCA '95). Higher-order difunctors are used to define signatures for compositional parametric generalised data types.
This class represents higher-order difunctors.
This class represents higher-order functors (Johann, Ghani, POPL '08) which are endofunctors on the category of endofunctors.
A higher-order functor
f also maps a natural transformation
g :-> h to a natural transformation
f g :-> f h
The parametrised constant functor.