Copyright	2010-2012 Edward Kmett
License	BSD
Maintainer	Edward Kmett <ekmett@gmail.com>
Stability	experimental
Portability	non-portable (either class-associated types or MPTCs with fundeps)
Safe Haskell	Safe-Inferred
Language	Haskell2010

Control.Categorical.Object

Description

This module declares the HasTerminalObject and HasInitialObject classes.

These are both special cases of the idea of a (co)limit.

Synopsis

Documentation

class Category k => HasTerminalObject k where Source

The Category (~>) has a terminal object Terminal (~>) such that for all objects a in (~>), there exists a unique morphism from a to Terminal (~>).

Associated Types

type Terminal k :: * Source

Methods

terminate :: a `k` Terminal k Source

class Category k => HasInitialObject k where Source

The Category (~>) has an initial (coterminal) object Initial (~>) such that for all objects a in (~>), there exists a unique morphism from Initial (~>) to a.

Associated Types

type Initial k :: * Source

Methods

initiate :: Initial k `k` a Source