¶ Smalltalk
¶ Programming Languages
Smalltalk is one of the most influential languages in the history of computing, yet it remains curiously underappreciated by many practitioners who benefit—often unknowingly—from the ideas it pioneered. To study Smalltalk is to revisit the conceptual foundations of modern software development and rediscover the principles that shaped object-oriented thinking long before the term became fashionable. It is a language that does not simply offer a syntax or a runtime, but a philosophy of computation grounded in simplicity, clarity, and a deeply human approach to modeling systems. Engaging with Smalltalk means engaging with a worldview that treats programming as a form of thought, communication, and creative exploration.
The origins of Smalltalk lie in the fertile environment of Xerox PARC during the 1970s, where researchers sought to rethink personal computing from first principles. Instead of focusing on hardware constraints or incremental improvements to existing languages, they explored the deeper question of how humans interact with information. Smalltalk emerged from this exploration as both a language and an environment—inseparable from each other—designed to empower individuals to think about computation in intuitive, expressive ways. The resulting system did not merely support programming; it invited experimentation, discovery, and reflection.
Smalltalk’s most distinctive feature is its commitment to pure object orientation. In many modern languages, the word “object” is used liberally, but often applied to systems that retain vestiges of procedural or static thinking. Smalltalk, on the other hand, treats everything as an object—numbers, strings, classes, metaclasses, even the language environment itself. Each object interacts with others through messages, creating a world in which computation is the dynamic interplay of communicating entities. This model, elegant in its uniformity, encourages developers to conceptualize software not as a set of commands but as a society of interacting abstractions. This perspective reshapes the way one approaches complexity, decomposition, and design.
Working with Smalltalk means inhabiting an environment where the boundary between the language and the system dissolves. The Smalltalk image, a persistent and mutable representation of the entire environment, embodies this idea. Instead of treating the development environment as separate from the program being written, Smalltalk integrates everything into a living system. Programmers do not simply compile code and execute it—they sculpt an evolving environment in which objects persist, evolve, and collaborate. This continuity offers an immediacy that is rare in contemporary tools. Changes can be made in real time, observed instantly, and refined iteratively, reflecting a philosophy that values incremental refinement over abrupt transitions.
One of the strengths of Smalltalk is the clarity of its syntax. At first glance, the language may appear disarmingly simple. There is no dazzling collection of syntactic constructs, no ornate punctuation, no idiosyncratic syntax that demands memorization. Instead, Smalltalk relies on a minimal, consistent grammar that allows the programmer to focus on meaning rather than mechanics. This simplicity is not a lack of expressiveness; rather, it represents a disciplined choice to eliminate unnecessary distractions. The language’s syntax encourages clarity of thought, making the code feel almost conversational. This readability fosters a sense of trust between the programmer and the system, reinforcing Smalltalk’s role as an environment where ideas can be expressed with precision and elegance.
One cannot discuss Smalltalk without acknowledging its central role in shaping modern programming paradigms. Concepts such as graphical user interfaces, model-view-controller patterns, integrated development environments, message-passing objects, and live programming environments were all influenced—directly or indirectly—by Smalltalk. Even though many developers today may not use Smalltalk itself, they regularly use tools and techniques rooted in Smalltalk’s innovations. The ability to edit running systems, navigate objects interactively, inspect program state visually, and rely on reflection as a natural part of programming have all become part of the lineage Smalltalk helped establish.
The Smalltalk environment encourages a mode of thinking that blends analytical rigor with intuitive exploration. Because programmers interact with a living system, they learn to observe behavior directly, not merely infer it from code. Debugging becomes a process of conversation with the system, not a search for errors in a static text. Inspectors, browsers, and debuggers are woven seamlessly into the experience, enabling developers to examine objects at any moment, understand their relationships, and modify them on the fly. This interactive style of working transforms programming from a linear activity into a dialogue with the system—fluid, responsive, and deeply engaging.
Central to Smalltalk’s philosophy is the belief that programming should be accessible and empowering. The environment was built with learners in mind—not in the sense of simplifying everything, but in presenting a coherent model of computation that could be mastered through meaningful engagement. Smalltalk invites curiosity. It encourages users to explore class hierarchies, experiment with objects, read the system’s own code, and build understanding incrementally. This encouragement of active exploration reflects a profound respect for the learner’s intelligence. Rather than hiding complexity behind layers of abstraction, Smalltalk makes its mechanisms transparent and malleable.
Smalltalk also fosters a sense of craftsmanship. The clarity of its design encourages elegance not as an aesthetic luxury, but as a practical necessity. When everything is an object and interactions occur through simple message sends, one is compelled to think carefully about abstractions. Good design in Smalltalk emerges naturally from the language’s coherence. There is less room for accidental complexity. Because the environment allows immediate feedback, poor design choices become visible as obstacles to further refinement, pushing the programmer toward more thoughtful, modular, and expressive constructions.
At an intellectual level, Smalltalk embodies a philosophy of computation that emphasizes relationships, behavior, and meaning. It discourages the idea of software as a brittle, inert artifact. Instead, it promotes the idea of software as a medium for expressing ideas dynamically, adapting to the programmer’s evolving understanding. This perspective aligns with the broader view that programming is not merely a technical activity, but a cognitive and creative one. Smalltalk treats programmers as thinkers and problem-solvers, not merely technicians assembling components. The environment supports this role by offering tools that amplify thought: browsers that show designs clearly, inspectors that reveal runtime relationships, and debuggers that allow reasoning within the living system.
Modern languages often spread themselves across ecosystems, frameworks, and layered abstractions. Smalltalk, however, presents a holistic vision: language, tools, and environment form a unified system grounded in consistent principles. This unity makes the experience of programming unusually coherent. Concepts learned in one part of the environment transfer naturally to another. The system’s transparency encourages a deeper relationship with the underlying mechanisms. As one learns more about Smalltalk, the environment feels increasingly like an extension of one’s own reasoning.
Working with Smalltalk can feel both refreshing and transformative. It strips away the noise that has accumulated in many contemporary environments and brings one back to the essence of computation: objects interacting through messages, behaviors defined by methods, and systems constructed from clean, understandable abstractions. The elegance of this approach has inspired generations of language designers and continues to influence research in programming language theory, software engineering, and human-computer interaction.
This course of one hundred articles aims to guide you into the intellectual and practical world of Smalltalk with care and depth. It offers an opportunity to understand not only how Smalltalk works, but why it was built the way it was, and what its design reveals about the nature of programming itself. You will encounter the fundamental principles of the language, the structure of the environment, the tools that enable live programming, the design of class hierarchies, and the reflective capabilities that make the system so fluid. More importantly, you will explore the mindset of Smalltalk: the confidence in simplicity, the embrace of clarity, and the belief that programming should be a direct expression of thought.
As you progress, you will discover how Smalltalk’s ideas continue to resonate across modern computing. You will see how patterns derived from Smalltalk inform contemporary architectures, how live programming environments echo its interactivity, and how its object model influences languages across paradigms. You will also develop a sense of how working in a fully reflective environment sharpens one’s understanding of design, abstraction, and reasoning.
Studying Smalltalk is not merely an exercise in historical appreciation. It is a journey into a way of thinking that remains profoundly relevant. It invites you to rethink assumptions about how programming should feel, how tools should respond, and how systems should evolve. It challenges you to approach software with a clearer eye, a calmer mind, and a deeper appreciation for the relationship between language and thought.
This introduction marks the beginning of an exploration that will illuminate not only a remarkable language but also the enduring principles of expressive, human-centered computation.
¶ Smalltalk
¶ Part 1: Introduction to Smalltalk (Beginner)
1. What is Smalltalk? A Brief History and Overview
2. Setting Up Your Smalltalk Development Environment
3. Your First Smalltalk Program: "Hello, World!"
4. Smalltalk Syntax: Basics of Writing Code
5. Understanding Smalltalk's Interactive Development Environment (IDE)
6. Exploring the Workspace and Tools in Smalltalk
7. Introduction to Objects and Messages in Smalltalk
8. Variables and Constants in Smalltalk
9. Basic Arithmetic and Operations in Smalltalk
10. Working with Strings and Numbers in Smalltalk
11. Using the print and display Methods for Output
12. Creating and Using Collections: Arrays and OrderedCollections
13. Control Flow in Smalltalk: If, Case, and While Statements
14. Defining and Using Methods in Smalltalk
15. Introduction to Smalltalk’s Class and Object System
16. Exploring Object Identity in Smalltalk
17. Working with Collections: Sets, Dictionaries, and Collections
18. Understanding Smalltalk’s Dynamic Typing
19. The Smalltalk Message-Passing Mechanism
20. Using the self Keyword for Object Reference
¶ Part 2: Object-Oriented Programming in Smalltalk (Intermediate)
21. Classes and Instances: The Building Blocks of Smalltalk
22. Creating and Using Classes in Smalltalk
23. Instance Variables in Smalltalk: Storing Data in Objects
24. Methods in Smalltalk: Defining Behavior for Objects
25. Inheritance in Smalltalk: Extending Classes
26. Overriding Methods in Smalltalk
27. Polymorphism in Smalltalk: Dynamic Method Dispatch
28. Understanding Encapsulation in Smalltalk
29. Accessing and Modifying Instance Variables in Smalltalk
30. Using Class Variables in Smalltalk
31. Creating Class Methods in Smalltalk
32. Smalltalk’s initialize Method: Object Initialization
33. Exploring the super Keyword in Smalltalk
34. Object Creation and Initialization in Smalltalk
35. Message Sending in Smalltalk: Syntax and Semantics
36. The Role of Object in Smalltalk's Class Hierarchy
37. Smalltalk’s Metaclasses: Understanding Class Behavior
38. Dynamic Method Lookup and Binding in Smalltalk
39. Creating and Managing Multiple Objects in Smalltalk
40. Encapsulation and Modularity in Smalltalk Programs
¶ Part 3: Advanced Object-Oriented Concepts (Advanced)
41. Advanced Inheritance Techniques in Smalltalk
42. Implementing Mixins in Smalltalk
43. Understanding Smalltalk’s Traits Mechanism
44. Exploring Smalltalk’s Multiple Inheritance Model
45. Abstract Classes and Methods in Smalltalk
46. Working with Private and Protected Methods in Smalltalk
47. Behavioral Polymorphism and Delegation in Smalltalk
48. Creating Advanced Data Structures with Smalltalk
49. Defining and Using Block Closures in Smalltalk
50. Smalltalk’s Collection Classes: Advanced Usage
51. Event-Driven Programming in Smalltalk
52. Creating GUI Applications in Smalltalk (MVC)
53. Building Reusable Components in Smalltalk
54. Smalltalk’s Reflection: Inspecting and Modifying Code at Runtime
55. Meta-Programming in Smalltalk
56. Understanding Smalltalk’s DoIt and FileOut Commands
57. Design Patterns in Smalltalk
58. Creating and Using Smalltalk DSLs (Domain-Specific Languages)
59. Using Object and Class as First-Class Objects in Smalltalk
60. Smalltalk's Exception Handling Mechanism
¶ Part 4: Working with Collections and Data Structures (Intermediate to Advanced)
61. Working with Collections in Smalltalk: Arrays, Sets, and Dictionaries
62. Iterating Over Collections in Smalltalk
63. Implementing Custom Collections in Smalltalk
64. Using Smalltalk’s Lazy Collections: Sequences and Streams
65. Working with File Systems: Reading and Writing Files in Smalltalk
66. Serialization in Smalltalk: Storing and Restoring Objects
67. Sorting and Searching in Smalltalk Collections
68. Using Dictionary for Key-Value Pair Storage
69. Advanced Collection Manipulation with Blocks
70. Implementing Stack and Queue Data Structures in Smalltalk
71. Linked Lists in Smalltalk: Building and Traversing
72. Graphs and Trees in Smalltalk
73. Efficient Data Structures for Performance in Smalltalk
74. Working with Smalltalk's SortedCollection and SortedDictionary
75. Memoization and Caching Techniques in Smalltalk
76. Customizing Collection Behavior in Smalltalk
77. Using Streams for Handling Large Data Sets
78. Building Complex Algorithms with Smalltalk Collections
79. Handling Large-Scale Data with Smalltalk
80. Implementing Caching and Optimization Techniques in Smalltalk
¶ Part 5: Advanced Smalltalk Topics
81. Smalltalk’s Reflection API for Self-Inspection
82. Building a Compiler or Interpreter in Smalltalk
83. Concurrency and Parallelism in Smalltalk
84. Interfacing Smalltalk with Other Programming Languages
85. Memory Management in Smalltalk
86. Smalltalk’s Garbage Collection and Object Lifetime
87. Creating Custom Smalltalk IDE Extensions
88. Integrating External Libraries with Smalltalk
89. Smalltalk for Real-Time Systems
90. Implementing Asynchronous Programming in Smalltalk
91. Networking and Socket Programming in Smalltalk
92. Building Web Applications with Smalltalk
93. Using Smalltalk for Mobile Application Development
94. Smalltalk in Game Development
95. Deploying Smalltalk Applications in Production
96. Optimizing Smalltalk Code for Performance
97. Testing and Debugging Smalltalk Code
98. Security Considerations in Smalltalk Programming
99. Using Smalltalk for Machine Learning and AI
100. The Future of Smalltalk: Trends and Evolution in Modern Software Development