Functional programming represents a programming paradigm in which the computations are evaluated by mathematical functions. The paradigm avoids changing states and using mutable data.
Every function in Haskell is a function in the purest mathematical sense. I/O operations which generate side-effects are represented in a mathematical way.
This chapter introduces you to the advantages of functional programming and then compares it to object-oriented programming.
The Advantages of Functional Programming
Free from side effects and bugs: As mentioned, functional programming does not maintain state. Therefore, you will not have side effects. In conclusion, you can write code free from side effects and bugs.
Efficiency: Functional programs consist of independent units that are able to run concurrently. This means the efficiency is higher.
Lazy evaluation: Functional programming supports lazy evaluation constructs such as lazy lists, lazy maps, and so on.
Nested functions: Functional programming supports nested functions.
Parallel programming efficiency: As mentioned, there is no mutable state, so there are no state-change issues.
Functional Programming vs. Object-Oriented Programming
Functional vs. Object-Oriented Programming
Functional Programming | OOP |
|---|---|
Functional programming uses immutable data. | Object-oriented programming uses mutable data. |
Functional programming is based on a declarative programming model. | Object-oriented programming is based on an imperative programming model. |
The focus is on “what you are doing.” | The focus is on “how you are doing.” |
Functional programming supports parallel programming. | Object-oriented programming is not suitable for parallel programming. |
Functions do not have side effects. | The methods can produce serious side effects. |
Flow control is based on using function invocation and function invocation with recursion. | Flow control is based on loops and conditional statements. |
The collection data is iterated using a recursion concept. | Object-oriented programming uses a loop concept to iterate Collection.Data such as the for-each loop in C# or Java. |
The execution order of statements is not important. | The execution order of statements is very important. |
There is support for “abstraction over data” and “abstraction over behavior.” | There is support only for “abstraction over data.” |
Summary
This chapter provided a short introduction to functional programming.
The chapters contained in this book cover the most important aspects and powerful elements (techniques, methods, and algorithms) that a beginner Haskell developer needs to get started with.