Disadvantages of Functional Programming “People say that practicing Zen is difficult, but there is a misunderstanding as to why.” Shunryu Suzuki, Zen Mind, Beginner’s Mind. When the problem domain is imperative, using a language with that characteristic is a natural and reasonable choice (since it is in general advisable to minimize the distance between the specification and implementation as part of reducing the number of subtle bugs). Generally experts have no difficulty writing fast functional programs; and in fact some of the best-performing parallel programs on 8- and 16-core processors are now written in Haskell. As I write about the benefits of functional programming in this chapter, I need to separate my answers into two parts. As I wrote in the “What is Functional Programming” lesson, a pure function is a function (a) whose output depends only on its input, and (b) has no side effects. Another disadvantage of procedural programming is that it struggles to handle situations in which a number of possible actions may lead to the desired result. The functional programming paradigm was explicitly created to support a pure functional approach to problem solving. 1. Unlike a statement, which is executed to assign variables, the evaluation of an expression produces a value. (This is like an Amazon Prime member who adds a family member to their account, and that person has one or more credit cards.) (Several FP experts say the same thing.) As one example of what I mean, in an Android football game I work on in my spare time, the OOP game framework I use provides an update method that I’m supposed to override to update the screen: Inside that method I have a lot of imperative GUI-drawing code that currently creates this UI: There isn’t a place for FP code at this point. Other “thick client,” GUI frameworks like Swing and JavaFX have similar interfaces, where they are OOP and imperative by design. For example, functional programming makes heavy use of recursion. Looking away from the details of specific implementations of functional programming, I see two key issues: It seems comparatively rare that it is practical to choose a functional model of some real-world problem over an imperative one. No piece of data in a functional program is modified twice by the same thread — let alone by two different threads. In Scala 2.12, it passes an Array[Int] directly to java.util.Arrays.sort(int[]). That means that you can … ), Functional idioms often do lots of inversion-of-control or laziness, which often has a negative impact on debugging (using a debugger). When you’re working with these frameworks you have to conform to their styles at this interface point, but there’s nothing to keep you from writing the rest of your code in an FP style. Below is a table listing the major programming paradigms and what sorts of problems they are commonly used for as well as some common disadvantages encountered. Disadvantage of the Object Oriented Programming The message based communication between many objects in a complex system is difficult to implement. As if all of this wasn't mind blowing, the functions that fold[lr]. Maybe both should be CW. If someone else has a particularly good implementation of some complex operation, it makes much more sense to use that instead of making your own. When would you NOT want to use functional programming? For this book, that’s the case regarding this section. This means it will probably be harder for you to write functional code, and it will almost certainly be harder for someone else to pick it up. (I’m not an expert on these tools, but at the time of this writing, most of these tools appear to be experimental or incomplete.). If you implemented these as subclasses of an abstract class in an OO, you'd have to write all those new functions as well. And I’ve been paid to write software since the early-1990s. As a subfield of declarative programming ("What should the program achieve? The graphs online for these functions are confusing as hell for someone who never saw them in college. I found that this situation makes it more difficult to learn Scala/FP. In this course, you’ll learn what functional programming is, how it’s used, and the features of Python that support it. Most functional languages optimize tail recursion so that this doesn't happen, but making an algorithm tail recursive can force you to do some rather unbeautiful code gymnastics (e.g., a tail-recursive map function creates a backwards list or has to build up a difference list, so it has to do extra work to get back to a normal mapped list in the correct order compared to the non-tail-recursive version). All of the functions follow the same pattern: That being said, the part that is hard is, “How do I glue all of these pure functions together in an FP style?” That question can lead to the code I showed in the first chapter: As you may be aware, when you first start programming in a pure FP style, gluing pure functions together to create a complete FP application is one of the biggest stumbling blocks you’ll encounter. Moreover, the object-oriented style relates data members and methods functions that support encapsulation and with the help of the concept of an inheritance, the code can be easily reusable but the major disadvantage of object-oriented programming paradigm is that if the code is not written properly t… :D ). I couldn't think of a better thread (well, one or two maybe) to help the interested reader reach their own conclusion on the precise merits (or lack thereof) of jdh's opinions. This helps the young learners and researchers to create knowledge in their scientific careers such as the studies … The framework expects me to update the pixels on the screen within this method, and if you’ve ever written anything like a video game, you know that to achieve the best performance — and avoid screen flickering — it’s generally best to update only the pixels that need to be changed. With Web applications like this, you have impure data coming into your Scala/Play application through data mappings and REST functions, and you probably also interact with impure database calls and impure network/internet I/O, but just like my football game, the “logic” portion of your application can be written with pure functions. For instance, when I first started working with Scala and needed a way to stub out new SBT projects, I wrote a Unix shell script. That is, until I became serious about writing pure FP code. Once a consensus is reached, that’s the style that you use. Those answers may be correct as of now, but they deal with FP being a new concept (an unavoidable issue) and not any inherent qualities. Just as I did in the previous chapter, I’ll first cover the “drawbacks of functional programming in general”: After that I’ll look at the more-specific “drawbacks of functional programming in Scala”: I write more about “hidden inputs” to functions in the “Pure Functions” chapter. Then again, I am a former chair of the International Conference on Functional Programming, so you may safely assume I am biased. Understanding why foldr can work on infinite lists requires at least a decent understanding of the languages lazy-behavoir and the minor detail that not all functions will force the evaluation of second argument. (Even with these sugars, some people might find it harder to deal with state/exceptions in FP. With features such as the availability of point-free style (aka tacit programming), functions tend to be radically simplified and easily recomposed for more generally reusable code compared to OOP. First, you start with a case class: Then, when your niece is born, you write code like this: Later, when she gets married and changes her last name, you write this: After that line of code, emily2.lastName has the value "Wells". The New Paradigm of Advantage Here’s something you might not know. However, if I add a new type to Animal, I have to go through each function to add support for it: Notice, though, that the exact opposite is true for object-oriented languages. Another way to think about this is instead of asking, “Is FP the right tool for every application I need to write?,” go ahead and ask that question with a different technology. As a simple example of this, when I owned a computer programming consulting company, the developers wanted a Java coding style that looked like this: As shown, they wanted curly braces on their own lines, and the code was indented four spaces. It’s a little early in this book for me to write about all of this, but ... the main benefit of the Haskell IO approach is that it creates a clear separation between (a) pure functions and (b) impure functions. For example, Joe Armstrong has written that Erlang processes — which are the equivalent of Akka actors — can be written in an imperative style. In the last chapter I looked at the benefits of functional programming, and as I showed, there are quite a few. In contrast, most mainstream languages, including object-oriented programming (OOP) languages such as C#, Visual Basic, C++, and Java, were designed to primarily support imperative (procedural) programming. That can make it be an inefficient choice when there are technical limitations involved due to the size that it can end up being. I am more looking for disadvantages of the paradigm as a whole, not things like "not widely used", or "no good debugger available". First, there are the benefits of functional programming in general.Second, there are more specific benefits that come from using functional programming in … In lessons later in this book I show solutions for how to glue pure functions together into a complete application. https://stackoverflow.com/questions/1786969/pitfalls-disadvantages-of-functional-programming/1787201#1787201. Its definitely not as easy as opening up Visual Studio for C#, or eclipse for Java. Possibly for the same reason, I knew about recursion, but never had to use it. One big disadvantage to functional programming is that on a theoretical level, it doesn't match the hardware as well as most imperative languages. It uses expressions instead of statements.… Enter the programming paradigm, which is a way to categorize programming languages by their central theory or methodology for handling data. Since computers are, at their core, machines, we need a good way to communicate with them. Functional programming continues to play a key role today – more than 60 years after its initial use in the LISP interpreter . 5. It can be inefficient. It's also true that you can't talk to your neighbor very easily, because functional-programming concepts are harder to teach and harder to learn than the object-oriented concepts behind languages like Smalltalk, Ruby, and C++. Then when you later want to add a new tab, you mutate the JTabbedPane instance like this: That’s the way thick client code usually works: you create components and then mutate them during the life of the application to create the desired user interface. Period. (For example its almost always easier to find something for Python, then it is for Haskell). It's hard for me to think of many downsides to functional programming. On top of this there is version with a slightly different syntax called foldr1 and foldl1 with different initial values. Re 2: Languages cannot be slower (or faster) than another language. What is it not so good at? Measurement (of which benchmarking is only one type) will show which is best; pontificating on a webpage won't. So this really is an “update” method, as opposed to a “completely redraw the screen” method. The difficulty of stateful programming. Why hasn't functional programming taken over yet? A functional program is modified twice by the same thing. ) rather be able to at... Easy as opening up Visual Studio for c #, or eclipse for Java in particular, that of.. User contributions under cc by-sa, `` pitfalls of Object Oriented programming is... 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