3.1 Reducers

      3.1.1 Reducer Constructors

      3.1.2 Reducer Operators

      3.1.3 Iteration and Comprehension with Reducers

      3.1.4 Reducer Contracts

      3.1.5 Reducer Chaperones and Impersonators

      3.1.6 Legacy Reduction APIs

    3.2 Transducers

      3.2.1 Element-Transforming Transducers

      3.2.2 Element-Removing Transducers

      3.2.3 Element-Rearranging Transducers

      3.2.4 Transducer Composition

      3.2.5 The Transduction Protocol

      3.2.6 Transducer Contracts

      3.2.7 Transducer Chaperones and Impersonators

      3.2.8 Debugging Transducers

      3.2.9 Testing Transducers