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Data.Generics.PlateTypeable |
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Description |
This module supplies a method for writing Biplate instances more easily.
To take an example:
data Expr = Var Int | Neg Expr | Add Expr Expr
instance Typeable Expr where ...
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 |+ y
instance Uniplate Expr where
uniplate = uniplateAll
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Synopsis |
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Documentation |
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module Data.Generics.Biplate |
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module Data.Typeable |
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The Class
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class PlateAll from to where |
This class represents going from the container type to the target.
This class should only be constructed with plate, |+ and |-
| | Methods | plateAll :: from -> Type from to |
| | Instances | PlateAll Bool to | PlateAll Char to | PlateAll Double to | PlateAll Float to | PlateAll Int to | PlateAll Integer to | PlateAll () to | (PlateAll a to, Typeable a, PlateAll b to, Typeable b, Typeable to, Uniplate to) => PlateAll (a, b) to | (PlateAll a to, Typeable a, PlateAll b to, Typeable b, PlateAll c to, Typeable c, Typeable to, Uniplate to) => PlateAll (a, b, c) to | (PlateAll a to, Typeable a, PlateAll b to, Typeable b, PlateAll c to, Typeable c, PlateAll d to, Typeable d, Typeable to, Uniplate to) => PlateAll (a, b, c, d) to | (PlateAll a to, Typeable a, PlateAll b to, Typeable b, PlateAll c to, Typeable c, PlateAll d to, Typeable d, PlateAll e to, Typeable e, Typeable to, Uniplate to) => PlateAll (a, b, c, d, e) to | (PlateAll from to, Typeable from, Typeable to, Uniplate to) => PlateAll (Maybe from) to | (PlateAll from to, Typeable from, Typeable to, Uniplate to) => PlateAll [from] to | (PlateAll a to, Typeable a, PlateAll b to, Typeable b, Typeable to, Uniplate to) => PlateAll (Either a b) to |
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uniplateAll :: PlateAll a b => a -> ([b], [b] -> a) |
This function is used to write a Uniplate instance from a PlateAll one
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The Combinators
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plate :: from -> Type from to |
The main combinator used to start the chain.
The following rule can be used for optimisation:
plate Ctor |- x == plate (Ctor x)
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(|+) :: (Typeable item, Typeable to, PlateAll item to) => Type (item -> from) to -> item -> Type from to |
the field to the right may contain the target.
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(|-) :: Type (item -> from) to -> item -> Type from to |
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.
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Produced by Haddock version 0.8 |