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

Language | Haskell98 |

- data Ann x f a = Ann x (f a)
- type AnnFix xT fT = Fix (Ann xT fT)
- rootAnn :: AnnFix x f -> x
- type AnnFix1 xT fT = fT (AnnFix xT fT)
- mkAnnFix :: x -> AnnFix1 x f -> AnnFix x f
- unannotate :: Functor f => AnnFix x f -> Fix f
- errorCata :: Traversable fT => ErrorAlgebra fT eT aT -> AnnFix xT fT -> Except [(eT, xT)] aT
- explore :: Foldable f => (x -> ExploreHints) -> AnnFix x f -> [Zipper (AnnFix x f)]
- findLeftmostDeepest :: Foldable f => (x -> Bool) -> AnnFix x f -> Maybe (Zipper (AnnFix x f))

# Annotations

Lifted annotation of functors.

Ann x (f a) |

mkAnnFix :: x -> AnnFix1 x f -> AnnFix x f Source #

Supply a tree with an annotation at the top level.

errorCata :: Traversable fT => ErrorAlgebra fT eT aT -> AnnFix xT fT -> Except [(eT, xT)] aT Source #

Reduces a tree to a value according to the algebra, collecting potential errors. The errors are combined with the annotations in the tree at the positions at which the errors occurred.

# Exploring annotated trees using zippers

explore :: Foldable f => (x -> ExploreHints) -> AnnFix x f -> [Zipper (AnnFix x f)] Source #

Explore an annotated tree. Starting with the root of the tree, at each
position the annotation at that position is matched against the
`ExploreHints`

predicates and all the selections where `matchHere`

was
positive are collected. The `exploreRight`

and `exploreDown`

allow pruning
of the tree, preventing entire parts from being visited.

findLeftmostDeepest :: Foldable f => (x -> Bool) -> AnnFix x f -> Maybe (Zipper (AnnFix x f)) Source #

Find the deepest node in an annotated tree that matches the predicate. Starting with the root, the predicate tells whether a node's annotation matches. If so, the search continues at the node's children and the node's siblings to the right are excluded from further exploration. If no child matches, the node itself is returned.