99-haskell-problems/Problems 61-69/problem_62.hs

8 lines
244 B
Haskell

data Tree a = Empty | Branch a (Tree a) (Tree a)
deriving (Show, Eq)
internals :: Tree a -> [a]
internals Empty = []
internals (Branch _ Empty Empty) = []
internals (Branch a branch1 branch2) =
(a : internals branch1) ++ internals branch2