Functional style as opposed to object-oriented style?

Here are some fundamental design concepts in Functional Programming (FP), along with their equivalents in Object-Oriented Programming (OOP):

1. Immutable Data Structures (FP) vs. Encapsulation (OOP)
2. In FP, data is immutable by design, ensuring that functions don't modify state. In OOP, encapsulation is used to hide internal state, but it can still be modified.
3. Pure Functions (FP) vs. Methods (OOP)
4. Pure functions in FP have no side effects and always return the same output for a given input. Methods in OOP can have side effects and may modify state.
5. Function Composition (FP) vs. Inheritance (OOP)
6. In FP, functions are composed together to create new functions. In OOP, classes inherit behavior from parent classes.
7. Higher-Order Functions (FP) vs. Strategy Pattern (OOP)
8. Higher-order functions in FP take functions as arguments or return functions as output. The Strategy pattern in OOP defines a family of algorithms, encapsulates each one, and makes them interchangeable.
9. Closures (FP) vs. Private Members (OOP)
10. Closures in FP capture variables from the surrounding scope, creating a private scope. Private members in OOP are used to hide internal implementation details.
11. Type Classes (FP) vs. Interfaces (OOP)
12. Type classes in FP define a set of functions that can be applied to a type. Interfaces in OOP define a contract that must be implemented by a class.
13. Monads (FP) vs. Try-Catch Blocks (OOP)
14. Monads in FP provide a way to handle errors and side effects in a pure functional way. Try-catch blocks in OOP are used to handle exceptions.

Some other FP concepts that don't have direct OOP equivalents include:

• Recursion: a fundamental concept in FP for solving problems by breaking them down into smaller sub-problems.
• Lazy Evaluation: a technique in FP where expressions are evaluated only when their values are actually needed.
• Pattern Matching: a feature in FP that allows functions to be defined by specifying multiple alternatives and selecting the first one that matches.

Keep in mind that these comparisons are not exact, and some concepts may overlap or have different nuances in each paradigm. However, this should give you a general idea of how FP design concepts relate to OOP concepts.