Enter the Haskell function definitions or load an example. You need to define source and get. The code is evaluated inside a let block, so you can define functions by pattern matching, but you cannot define new data types. The type classes required by the bidirectionalization functions are defined for Maybe, [], and this simple tree type:

data Tree a = Leaf a | Node (Tree a) (Tree a)

halve flatten rmdups top3 tail sieve doubleList tail/rmdups
source = [1,2,3,4,5,6,7,8,9,10] get as = take (length as `div` 2) as

Your definitions have the following types:

get :: [a] -> [a]
source :: (Num t) => [t]

You can use get source to calculate a view which you can then modify. If you have defined view, then you can use the bidirectionalizer to calculate the updated source. The result will be shown in the code edit frame above.

Evaluate