| Safe Haskell | Safe |
|---|---|
| Language | Haskell2010 |
Data.Generics.Fixplate.Attributes
Contents
Description
Synthetising attributes, partly motivated by Attribute Grammars, and partly by recursion schemes.
TODO: better organization / interface to all these functions...
- newtype Attrib f a = Attrib {}
- annMap :: Functor f => (a -> b) -> Attr f a -> Attr f b
- synthetise :: Functor f => (f a -> a) -> Mu f -> Attr f a
- synthetise' :: Functor f => (a -> f b -> b) -> Attr f a -> Attr f b
- synthetiseList :: (Functor f, Foldable f) => ([a] -> a) -> Mu f -> Attr f a
- synthetiseM :: (Traversable f, Monad m) => (f a -> m a) -> Mu f -> m (Attr f a)
- synthCata :: Functor f => (f a -> a) -> Mu f -> Attr f a
- scanCata :: Functor f => (a -> f b -> b) -> Attr f a -> Attr f b
- synthPara :: Functor f => (f (Mu f, a) -> a) -> Mu f -> Attr f a
- synthPara' :: Functor f => (Mu f -> f a -> a) -> Mu f -> Attr f a
- scanPara :: Functor f => (Attr f a -> f b -> b) -> Attr f a -> Attr f b
- synthZygo_ :: Functor f => (f b -> b) -> (f (b, a) -> a) -> Mu f -> Attr f a
- synthZygo :: Functor f => (f b -> b) -> (f (b, a) -> a) -> Mu f -> Attr f (b, a)
- synthZygoWith :: Functor f => (b -> a -> c) -> (f b -> b) -> (f (b, a) -> a) -> Mu f -> Attr f c
- synthAccumCata :: Functor f => (f acc -> (acc, b)) -> Mu f -> (acc, Attr f b)
- synthAccumPara' :: Functor f => (Mu f -> f acc -> (acc, b)) -> Mu f -> (acc, Attr f b)
- mapAccumCata :: Functor f => (f acc -> b -> (acc, c)) -> Attr f b -> (acc, Attr f c)
- synthCataM :: (Traversable f, Monad m) => (f a -> m a) -> Mu f -> m (Attr f a)
- synthParaM :: (Traversable f, Monad m) => (f (Mu f, a) -> m a) -> Mu f -> m (Attr f a)
- synthParaM' :: (Traversable f, Monad m) => (Mu f -> f a -> m a) -> Mu f -> m (Attr f a)
- inherit :: Functor f => (Mu f -> a -> a) -> a -> Mu f -> Attr f a
- inherit' :: Functor f => (a -> b -> a) -> a -> Attr f b -> Attr f a
- inherit2 :: Functor f => (Mu f -> a -> (b, a)) -> a -> Mu f -> Attr f b
- inheritM :: (Traversable f, Monad m) => (Mu f -> a -> m a) -> a -> Mu f -> m (Attr f a)
- inheritM_ :: (Traversable f, Monad m) => (Mu f -> a -> m a) -> a -> Mu f -> m ()
- topDownSweepM :: (Traversable f, Monad m) => (f () -> a -> m (f a)) -> a -> Mu f -> m ()
- topDownSweepM' :: (Traversable f, Monad m) => (b -> f b -> a -> m (f a)) -> a -> Attr f b -> m ()
- synthAccumL :: Traversable f => (a -> Mu f -> (a, b)) -> a -> Mu f -> (a, Attr f b)
- synthAccumR :: Traversable f => (a -> Mu f -> (a, b)) -> a -> Mu f -> (a, Attr f b)
- synthAccumL_ :: Traversable f => (a -> Mu f -> (a, b)) -> a -> Mu f -> Attr f b
- synthAccumR_ :: Traversable f => (a -> Mu f -> (a, b)) -> a -> Mu f -> Attr f b
- enumerateNodes :: Traversable f => Mu f -> (Int, Attr f Int)
- enumerateNodes_ :: Traversable f => Mu f -> Attr f Int
- synthTransform :: Traversable f => (f a -> a) -> (Attr f a -> Maybe (f (Attr f a))) -> Attr f a -> Attr f a
- synthTransform' :: Traversable f => (f (Attr f a) -> a) -> (Attr f a -> Maybe (f (Attr f a))) -> Attr f a -> Attr f a
- synthRewrite :: Traversable f => (f a -> a) -> (Attr f a -> Maybe (f (Attr f a))) -> Attr f a -> Attr f a
- synthRewrite' :: Traversable f => (f (Attr f a) -> a) -> (Attr f a -> Maybe (f (Attr f a))) -> Attr f a -> Attr f a
- annZip :: Functor f => Mu (Ann (Ann f a) b) -> Attr f (a, b)
- annZipWith :: Functor f => (a -> b -> c) -> Mu (Ann (Ann f a) b) -> Attr f c
- annZip3 :: Functor f => Mu (Ann (Ann (Ann f a) b) c) -> Attr f (a, b, c)
- annZipWith3 :: Functor f => (a -> b -> c -> d) -> Mu (Ann (Ann (Ann f a) b) c) -> Attr f d
Documentation
A newtype wrapper around Attr f a so that we can make Attr f
an instance of Functor, Foldable and Traversable (and Comonad). This is necessary
since Haskell does not allow partial application of type synonyms.
Equivalent to the co-free comonad.
annMap :: Functor f => (a -> b) -> Attr f a -> Attr f b Source
Map over annotations
annMap f = unAttrib . fmap f . Attrib
Synthetised attributes
synthetise :: Functor f => (f a -> a) -> Mu f -> Attr f a Source
Synthetised attributes are created in a bottom-up manner.
As an example, the sizes function computes the sizes of all
subtrees:
sizes :: (Functor f, Foldable f) => Mu f -> Attr f Int sizes = synthetise (\t -> 1 + sum t)
(note that sum here is Data.Foldable.sum == Prelude.sum . Data.Foldable.toList)
See also synthCata.
synthetise' :: Functor f => (a -> f b -> b) -> Attr f a -> Attr f b Source
Generalization of scanr for trees. See also scanCata.
synthetiseList :: (Functor f, Foldable f) => ([a] -> a) -> Mu f -> Attr f a Source
List version of synthetise (compare with Uniplate)
synthetiseM :: (Traversable f, Monad m) => (f a -> m a) -> Mu f -> m (Attr f a) Source
Monadic version of synthetise.
Synthetised attributes as generalized cata- and paramorphisms
synthCata :: Functor f => (f a -> a) -> Mu f -> Attr f a Source
Synonym for synthetise, motivated by the equation
attribute . synthCata f == cata f
That is, it attributes all subtrees with the result of the corresponding catamorphism.
scanCata :: Functor f => (a -> f b -> b) -> Attr f a -> Attr f b Source
Synonym for synthetise'. Note that this could be a special case of synthCata:
scanCata f == annZipWith (flip const) . synthCata (\(Ann a x) -> f a x)
Catamorphim (cata) is the generalization of foldr from lists to trees;
synthCata is one generalization of scanr, and scanCata is another generalization.
synthPara :: Functor f => (f (Mu f, a) -> a) -> Mu f -> Attr f a Source
Attributes all subtrees with the result of the corresponding paramorphism.
attribute . synthPara f == para f
synthPara' :: Functor f => (Mu f -> f a -> a) -> Mu f -> Attr f a Source
Another version of synthPara.
attribute . synthPara' f == para' f
synthZygo_ :: Functor f => (f b -> b) -> (f (b, a) -> a) -> Mu f -> Attr f a Source
Synthetising zygomorphism.
attribute . synthZygo_ g h == zygo_ g h
synthZygoWith :: Functor f => (b -> a -> c) -> (f b -> b) -> (f (b, a) -> a) -> Mu f -> Attr f c Source
synthAccumCata :: Functor f => (f acc -> (acc, b)) -> Mu f -> (acc, Attr f b) Source
Accumulating catamorphisms. Generalization of mapAccumR from lists to trees.
synthAccumPara' :: Functor f => (Mu f -> f acc -> (acc, b)) -> Mu f -> (acc, Attr f b) Source
Accumulating paramorphisms.
mapAccumCata :: Functor f => (f acc -> b -> (acc, c)) -> Attr f b -> (acc, Attr f c) Source
Could be a special case of synthAccumCata:
mapAccumCata f == second (annZipWith (flip const)) . synthAccumCata (\(Ann b t) -> f b t) where second g (x,y) = (x, g y)
synthCataM :: (Traversable f, Monad m) => (f a -> m a) -> Mu f -> m (Attr f a) Source
Synonym for synthetiseM. If you don't need the result, use cataM_ instead.
synthParaM :: (Traversable f, Monad m) => (f (Mu f, a) -> m a) -> Mu f -> m (Attr f a) Source
Monadic version of synthPara. If you don't need the result, use paraM_ instead.
synthParaM' :: (Traversable f, Monad m) => (Mu f -> f a -> m a) -> Mu f -> m (Attr f a) Source
Monadic version of synthPara'.
Inherited attributes
inherit :: Functor f => (Mu f -> a -> a) -> a -> Mu f -> Attr f a Source
Inherited attributes are created in a top-down manner.
As an example, the depths function computes the depth
(the distance from the root, incremented by 1) of all subtrees:
depths :: Functor f => Mu f -> Attr f Int depths = inherit (\_ i -> i+1) 0
inherit' :: Functor f => (a -> b -> a) -> a -> Attr f b -> Attr f a Source
Generalization of scanl from lists to trees.
inherit2 :: Functor f => (Mu f -> a -> (b, a)) -> a -> Mu f -> Attr f b Source
Generalization of inherit. TODO: better name?
inheritM :: (Traversable f, Monad m) => (Mu f -> a -> m a) -> a -> Mu f -> m (Attr f a) Source
Monadic version of inherit.
Top-down folds
topDownSweepM :: (Traversable f, Monad m) => (f () -> a -> m (f a)) -> a -> Mu f -> m () Source
Monadic top-down "sweep" of a tree. It's kind of a more complicated folding version of inheritM.
This is unsafe in the sense that the user is responsible to retain the shape of the node.
TODO: better name?
topDownSweepM' :: (Traversable f, Monad m) => (b -> f b -> a -> m (f a)) -> a -> Attr f b -> m () Source
An attributed version of topDownSweepM. Probably more useful.
Traversals
synthAccumL :: Traversable f => (a -> Mu f -> (a, b)) -> a -> Mu f -> (a, Attr f b) Source
Synthetising attributes via an accumulating map in a left-to-right fashion
(the order is the same as in foldl).
synthAccumR :: Traversable f => (a -> Mu f -> (a, b)) -> a -> Mu f -> (a, Attr f b) Source
Synthetising attributes via an accumulating map in a right-to-left fashion
(the order is the same as in foldr).
synthAccumL_ :: Traversable f => (a -> Mu f -> (a, b)) -> a -> Mu f -> Attr f b Source
synthAccumR_ :: Traversable f => (a -> Mu f -> (a, b)) -> a -> Mu f -> Attr f b Source
enumerateNodes :: Traversable f => Mu f -> (Int, Attr f Int) Source
We use synthAccumL to number the nodes from 0 to (n-1) in
a left-to-right traversal fashion, where
n == length (universe tree) is the number of substructures,
which is also returned.
enumerateNodes_ :: Traversable f => Mu f -> Attr f Int Source
Resynthetising transformations
synthTransform :: Traversable f => (f a -> a) -> (Attr f a -> Maybe (f (Attr f a))) -> Attr f a -> Attr f a Source
Bottom-up transformations which automatically resynthetise attributes in case of changes.
synthTransform' :: Traversable f => (f (Attr f a) -> a) -> (Attr f a -> Maybe (f (Attr f a))) -> Attr f a -> Attr f a Source
synthRewrite :: Traversable f => (f a -> a) -> (Attr f a -> Maybe (f (Attr f a))) -> Attr f a -> Attr f a Source
Bottom-up transformations to normal form (applying transformation exhaustively) which automatically resynthetise attributes in case of changes.
synthRewrite' :: Traversable f => (f (Attr f a) -> a) -> (Attr f a -> Maybe (f (Attr f a))) -> Attr f a -> Attr f a Source
Stacking attributes
annZip :: Functor f => Mu (Ann (Ann f a) b) -> Attr f (a, b) Source
Merges two layers of annotations into a single one.