Compose functions in Java
Java interview exercise on Generics & Optional, difficulty 2 of 3. Solve it in the editor beside a worked example, or cold in Interview mode with the example hidden; the tests run the moment you do.
Write pipeline(steps) that composes a list of UnaryOperator<String> into one UnaryOperator<String> applying them in order (the first step first). An empty list gives the identity function. Fold with andThen, or loop.
Each exercise pairs a worked example with a twin problem to solve in a real editor; the tests run the moment you do. Interview mode hides the example: solve it from memory, without the hint or the solution, and it counts as solved cold. Progress is saved in your browser, and in your account if you sign in.