| Copyright | (C) 2017 Csongor Kiss |
|---|---|
| License | BSD3 |
| Maintainer | Csongor Kiss <kiss.csongor.kiss@gmail.com> |
| Stability | experimental |
| Portability | non-portable |
| Safe Haskell | Safe |
| Language | Haskell2010 |
Data.Generics.Product.Subtype
Description
Structural subtype relationship between record types.
The running example in this module is the following two types:
module Test where
import GHC.Generics
import Data.Generics.Record
data Human = Human
{ name :: String
, age :: Int
, address :: String
} deriving (Generic, Show)
data Animal = Animal
{ name :: String
, age :: Int
} deriving (Generic, Show)
human :: Human
human = Human "Tunyasz" 50 "London"
- class Subtype sup sub where
Documentation
class Subtype sup sub where Source #
Structural subtype relationship
sub is a (structural) subtype of sup, if its fields are a subset of
those of sup.
Methods
super :: Lens' sub sup Source #
Structural subtype lens. Given a subtype relationship sub :< sup,
we can focus on the sub structure of sup.
>>>human ^. super @AnimalAnimal {name = "Tunyasz", age = 50}
>>>set (super @Animal) (Animal "dog" 10) humanHuman {name = "dog", age = 10, address = "London"}
Cast the more specific subtype to the more general supertype
>>>upcast human :: AnimalAnimal {name = "Tunyasz", age = 50}
smash :: sup -> sub -> sub Source #
Plug a smaller structure into a larger one
>>>smash (Animal "dog" 10) humanHuman {name = "dog", age = 10, address = "London"}