Data.Tree.Lens

valueroot :: Functor f => (a -> f a) -> Tree a -> f (Tree a)

A Lens that focuses on the root of a Tree.

Example1 expression

>>> view root $ Node 42 []42

valuebranches :: Functor f => ([Tree a] -> f [Tree a]) -> Tree a -> f (Tree a)

A Lens returning the direct descendants of the root of a Tree

view branches ≡ subForest