Safe Haskell | Safe |
---|---|

Language | Haskell98 |

The Point data type which generalizes the different lenses and forms the
basis for vertical composition using the `Applicative`

type class.

- data Point cat g i f o = Point (cat f o) (cat (cat o i, f) g)
- get :: Point cat g i f o -> cat f o
- modify :: Point cat g i f o -> cat (cat o i, f) g
- set :: Arrow arr => Point arr g i f o -> arr (i, f) g
- identity :: ArrowApply arr => Point arr f f o o
- compose :: ArrowApply cat => Point cat t i b o -> Point cat g t f b -> Point cat g i f o
- data Iso cat i o = Iso {}
- inv :: Iso cat i o -> Iso cat o i
- type Total = (->)
- type Partial = Kleisli Maybe
- type Failing e = Kleisli (Either e)
- class Arrow a => ArrowFail e a where

# The point data type that generalizes lens.

data Point cat g i f o Source #

Abstract Point datatype. The getter and modifier operations work in some category. The type of the value pointed to might change, thereby changing the type of the outer structure.

Point (cat f o) (cat (cat o i, f) g) |

identity :: ArrowApply arr => Point arr f f o o Source #

Identity Point. Cannot change the type.

compose :: ArrowApply cat => Point cat t i b o -> Point cat g t f b -> Point cat g i f o Source #

Point composition.

# Working with isomorphisms.

# Specialized lens contexts.

type Failing e = Kleisli (Either e) Source #

Context that represents computations that might fail with some error.

# Arrow type class for failing with some error.

class Arrow a => ArrowFail e a where Source #

The ArrowFail class is similar to `ArrowZero`

, but additionally embeds
some error value in the computation instead of throwing it away.

# Orphan instances

Functor f => Functor (Kleisli f i) Source # | Missing Functor instance for Kleisli. |

Applicative f => Applicative (Kleisli f i) Source # | Missing Applicative instance for Kleisli. |

Alternative f => Alternative (Kleisli f i) Source # | Missing Alternative instance for Kleisli. |