| Safe Haskell | None |
|---|---|
| Language | Haskell2010 |
Data.Generics.Uniplate.Typeable
Description
RECOMMENDATION: Use Data.Generics.Uniplate.Data instead - it usually performs faster (sometimes significantly so) and requires no special instance declarations.
This module supplies a method for writing Uniplate / Biplate instances. One
instance declaration is required for each data type you wish to work with. The
instances can be generated using Derive: http://community.haskell.org/~ndm/derive/.
To take an example:
data Expr = Var Int | Neg Expr | Add Expr Expr
deriving Typeable
instance (Typeable a, Uniplate a) => PlateAll Expr a where
plateAll (Var x ) = plate Var |+ x
plateAll (Neg x ) = plate Neg |+ x
plateAll (Add x y) = plate Add |+ x |+ ySynopsis
- module Data.Generics.Uniplate.Operations
- module Data.Typeable
- class PlateAll from to where
- plateAll :: from -> Type from to
- plate :: from -> Type from to
- (|+) :: (Typeable item, Typeable to, PlateAll item to) => Type (item -> from) to -> item -> Type from to
- (|-) :: Type (item -> from) to -> item -> Type from to
- plateProject :: (Typeable item, Typeable to, PlateAll item to) => (from -> item) -> (item -> from) -> from -> Type from to
Documentation
module Data.Typeable
The Class
class PlateAll from to where Source #
This class should be defined for each data type of interest.
Methods
Instances
The Combinators
(|+) :: (Typeable item, Typeable to, PlateAll item to) => Type (item -> from) to -> item -> Type from to Source #
The field to the right may contain the target.
(|-) :: Type (item -> from) to -> item -> Type from to Source #
The field to the right does not contain the target. This can be used as either an optimisation, or more commonly for excluding primitives such as Int.
plateProject :: (Typeable item, Typeable to, PlateAll item to) => (from -> item) -> (item -> from) -> from -> Type from to Source #
Write an instance in terms of a projection/injection pair. Usually used to define instances for abstract containers such as Map:
instance (Ord a, Typeable a, PlateAll a c, Typeable b, PlateAll b c,
Typeable c, PlateAll c c) => PlateAll (Map.Map a b) c where
plateAll = plateProject Map.toList Map.fromList