2 Building Abstractions with Data
2.1 Introduction to Data Abstraction
2.1.1 Example: Arithmetic Operations for Rational Numbers
2.1.2 Abstraction Barriers
2.1.3 What Is Meant by Data?
2.1.4 Extended Exercise: Interval Arithmetic
2.2 Hierarchical Data and the Closure Property
2.2.1 Representing Sequences
2.2.2 Hierarchical Structures
2.2.3 Sequences as Conventional Interfaces
2.2.4 Example: A Picture Language
2.3 Symbolic Data
2.3.1 Quotation
2.3.2 Example: Symbolic Differentiation
2.3.3 Example: Representing Sets
2.3.4 Example: Huffman Encoding Trees
2.4 Multiple Representations for Abstract Data
2.4.1 Representations for Complex Numbers
2.4.2 Tagged data
2.4.3 Data-Directed Programming and Additivity
2.5 Systems with Generic Operations
2.5.1 Generic Arithmetic Operations
2.5.2 Combining Data of Different Types
2.5.3 Example: Symbolic Algebra
3 Modularity, Objects, and State
3.1 Assignment and Local State
3.1.1 Local State Variables
3.1.2 The Benefits of Introducing Assignment
3.1.3 The Costs of Introducing Assignment
3.2 The Environment Model of Evaluation
3.2.1 The Rules for Evaluation
3.2.2 Applying Simple Procedures
3.2.3 Frames as the Repository of Local State
3.2.4 Internal Definitions
3.3 Modeling with Mutable Data
3.3.1 Mutable List Structure
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