semigroupoids-5.2: Semigroupoids: Category sans id

Copyright(C) 2007-2015 Edward Kmett
LicenseBSD-style (see the file LICENSE)
MaintainerEdward Kmett <ekmett@gmail.com>
Stabilityprovisional
Portabilityportable
Safe HaskellSafe
LanguageHaskell98

Data.Semigroupoid.Dual

Description

A semigroupoid satisfies all of the requirements to be a Category except for the existence of identity arrows.

Documentation

newtype Dual k a b Source #

Constructors

Dual 

Fields

Instances

Category k k1 => Category k (Dual k k k1) Source # 

Methods

id :: cat a a #

(.) :: cat b c -> cat a b -> cat a c #

Semigroupoid k k1 => Semigroupoid k (Dual k k k1) Source # 

Methods

o :: c j k -> c i j -> c i k Source #

Groupoid k k1 => Groupoid k (Dual k k k1) Source # 

Methods

inv :: k a b -> k b a Source #