Add solution for Exercise 2.76 in SICP (#153)

The solution provides a detailed discussion of different strategies for adding new types or operations in a system with generic operations.

README.md

@@ -1,7 +1,7 @@
 # Solving exercises from SICP with Clojure
 
 [![Clojure CI](https://github.com/SmetDenis/Clojure-Sicp/actions/workflows/main.yml/badge.svg?branch=main)](https://github.com/SmetDenis/Clojure-Sicp/actions/workflows/main.yml)
-![Progress](https://progress-bar.dev/121/?scale=356&title=Solved&width=500&suffix=)
+![Progress](https://progress-bar.dev/122/?scale=356&title=Solved&width=500&suffix=)
 
 SICP (Structure and Interpretation of Computer Programs) is the book of Harold Abelson and Gerald
 Jay Sussman on basics of computer science and software engineering.
@@ -42,7 +42,7 @@ Jay Sussman on basics of computer science and software engineering.
 
 ### Chapter 2 - Building Abstractions with Data
 
-![Progress](https://progress-bar.dev/75/?scale=97&title=Solved&width=500&suffix=)
+![Progress](https://progress-bar.dev/76/?scale=97&title=Solved&width=500&suffix=)
 
 * [2.1](https://sarabander.github.io/sicp/html/Chapter-2.xhtml#Chapter-2) Introduction to Data Abstraction - [Code in book](src/sicp/chapter_2/part_1/book_2_1.clj)
   * [2.1.1](https://sarabander.github.io/sicp/html/2_002e1.xhtml#g_t2_002e1_002e1) Example: Arithmetic Operations for Rational Numbers - [2.1](src/sicp/chapter_2/part_1/ex_2_01.clj)
@@ -62,7 +62,7 @@ Jay Sussman on basics of computer science and software engineering.
 * [2.4](https://sarabander.github.io/sicp/html/2_002e4.xhtml#g_t2_002e4) Multiple Representations for Abstract Data
   * [2.4.1](https://sarabander.github.io/sicp/html/2_002e4.xhtml#g_t2_002e4_002e1) Representations for Complex Numbers
   * [2.4.2](https://sarabander.github.io/sicp/html/2_002e4.xhtml#g_t2_002e4_002e2) Tagged data
-  * [2.4.3](https://sarabander.github.io/sicp/html/2_002e4.xhtml#g_t2_002e4_002e3) Data-Directed Programming and Additivity - [2.73](src/sicp/chapter_2/part_4/ex_2_73.clj), [2.74](src/sicp/chapter_2/part_4/ex_2_74.clj), [2.75](src/sicp/chapter_2/part_4/ex_2_75.clj)
+  * [2.4.3](https://sarabander.github.io/sicp/html/2_002e4.xhtml#g_t2_002e4_002e3) Data-Directed Programming and Additivity - [2.73](src/sicp/chapter_2/part_4/ex_2_73.clj), [2.74](src/sicp/chapter_2/part_4/ex_2_74.clj), [2.75](src/sicp/chapter_2/part_4/ex_2_75.clj), [2.76](src/sicp/chapter_2/part_4/ex_2_76.clj)
 * 2.5 Systems with Generic Operations
   * 2.5.1 Generic Arithmetic Operations
   * 2.5.2 Combining Data of Different Types

src/sicp/chapter_2/part_4/ex_2_76.clj

@@ -0,0 +1,29 @@
+(ns sicp.chapter-2.part-4.ex-2-76)
+
+; Exercise 2.76
+;
+; As a large system with generic operations evolves, new types of data objects or new operations
+; may be needed. For each of the three strategies—generic operations with explicit dispatch,
+; data-directed style, and message-passing-style—describe the changes that must be made to
+; a system in order to add new types or new operations. Which organization would be most appropriate
+; for a system in which new types must often be added? Which would be most appropriate for
+; a system in which new operations must often be added?
+
+; Answer
+;
+; |------------------------|----------------------------------|-------------------------------------|
+; | Style                  | Adding New Types                 | Adding New Operations               |
+; |------------------------|----------------------------------|-------------------------------------|
+; | Generic Operations     | Add a new branch in each         | Create a new procedure containing   |
+; | with Explicit Dispatch | operation on the generic data    | the dispatch for all types          |
+; |------------------------|----------------------------------|-------------------------------------|
+; | Data-Directed Style    | Add the corresponding operations | Add the operation to each type      |
+; |                        | into the registry table          | package and register them in table  |
+; |------------------------|----------------------------------|-------------------------------------|
+; | Message-Passing Style  | Implement the new type with      | Add the operation into              |
+; |                        | no extra effort needed           | the implementation of each type     |
+; |------------------------|----------------------------------|-------------------------------------|
+; | Best Suited For        | Data-Directed Style and Message- | Explicit-Dispatch and Data-         |
+; |                        | Passing Style: Systems with      | Directed Style: Systems with        |
+; |                        | frequent addition of new types   | frequent addition of new operations |
+; |------------------------|----------------------------------|-------------------------------------|