#Structure and Interpretation of Computer Programs Answers ###Note DrRacket is recommended. If any bug caught, please let me know,thanks. ###Content Chapter 2. Building Abstractions with Data Chapter2.1 Introduction to Data Abstraction Chapter2.2 Hierarchical Data and the Closure Property Chapter2.3 Symbolic Data Chapter2.4 Multiple Representations for Abstract Data Chapter2.5 Systems with Generic Operations Chapter 3. Modularity, Objects, and State Chapter3.1 Assignment and Local State Chapter3.2 The Environment Model of Evaluation Chapter3.3 Modeling with Mutable Data