Modulelinear-base-0.4.0Haskell2010

Data.Bifunctor.Linear

This module provides Bifunctor and related classes.

Bifunctor

Use a bifunctor instance to map functions over data structures that have two type paramaters a and b and could be have a functor instance for either the as or bs. For instance, you might want to map a function on either the left or right element of a (Int, Bool):

import Prelude.Linear
import Data.Bifunctor.Linear

-- Map over the second element
negateRight :: (Int, Bool) %1-> (Int, Bool)
negateRight x = second not x

2 classes

Packagelinear-base-0.4.0
Exports2
LanguageHaskell2010
LicenceMIT
SourceLinear.hs

classclass Bifunctor (p :: Type -> Type -> Type) where

The Bifunctor class

Laws

If bimap is supplied, then bimap id id = id

If first and second are supplied, then first id ≡ id second id ≡ id
If all are supplied, then @bimap f g = first f . second g

Methods

bimap :: (a %1 -> b) -> (c %1 -> d) -> p a c %1 -> p b d
first :: (a %1 -> b) -> p a c %1 -> p b c
second :: (b %1 -> c) -> p a b %1 -> p a c

Instances2Bifunctor

Bifunctor EitherDefined in linear-base-0.4.0 · Data.Bifunctor.Linear.Internal.Bifunctor
Bifunctor Tuple2Defined in linear-base-0.4.0 · Data.Bifunctor.Linear.Internal.Bifunctor

classclass Bifunctor m => SymmetricMonoidal (m :: Type -> Type -> Type) u | m -> u, u -> m where

A SymmetricMonoidal class

This allows you to shuffle around a bifunctor nested in itself and swap the places of the two types held in the bifunctor. For instance, for tuples:

You can use lassoc :: (a,(b,c)) %1-> ((a,b),c) and then use first to access the a
You can use the dual, i.e., rassoc :: ((a,b),c) %1-> (a,(b,c)) and then second
You can swap the first and second values with swap :: (a,b) %1-> (b,a)

Laws

```
swap . swap = id
```
```
rassoc . lassoc = id
```
```
lassoc . rassoc = id
```

second swap . rassoc . first swap = rassoc . swap . rassoc

Methods

rassoc :: m (m a b) c %1 -> m a (m b c)
lassoc :: m a (m b c) %1 -> m (m a b) c
swap :: m a b %1 -> m b a

Instances2SymmetricMonoidal

SymmetricMonoidal Either VoidDefined in linear-base-0.4.0 · Data.Bifunctor.Linear.Internal.SymmetricMonoidal
SymmetricMonoidal Tuple2 ()Defined in linear-base-0.4.0 · Data.Bifunctor.Linear.Internal.SymmetricMonoidal