The purest coding style, where bugs are near impossible

Summary

This script introduces functional programming, a paradigm that emphasizes the use of pure functions, immutability, and higher-order functions to create a more declarative, deterministic, and maintainable code. It explains concepts like closures, currying, and the benefits of a functional approach, such as reduced side effects and improved code modularity, while acknowledging its complexity and the learning curve involved.

Takeaways

• 🌳 **Programming Paradigms**: Functional programming is a paradigm often used without awareness, branching from the declarative side of the programming language tree.
• 💡 **Core Concepts**: Functional programming emphasizes the use of functions, immutability, pure code, and the avoidance of side effects to create a more predictable and maintainable code structure.
• 🔄 **Closures**: Closures are functions that remember their scope, allowing access to parent function's data even after the parent function has finished executing, which is crucial for functional programming.
• 📈 **Higher Order Functions**: Functions that operate on other functions, such as filter(), sort(), and map(), are fundamental in functional programming, promoting reusable and composable code modules.
• 🛡️ **Immutability**: By avoiding changes to data, functional programming aims to eliminate side effects, ensuring the same output for the same input, which simplifies reasoning about code behavior.
• 🗝️ **Currying**: This technique involves breaking down a function with multiple arguments into a sequence of functions, each with a single argument, enhancing code flexibility and reusability.
• 📦 **Encapsulation**: Using closures to encapsulate data and state can mimic object-oriented programming principles, providing private data scopes and controlled access through returned closures.
• 🚀 **Optimization and Performance**: Functional programming can lead to optimizations like lazy evaluation and automatic parallelization due to its declarative nature and emphasis on immutability.
• 🤔 **Learning Curve**: While functional programming offers many benefits, it also presents challenges such as a steeper learning curve and potential difficulties in optimization compared to imperative styles.
• 🌟 **Benefits**: Adopting functional programming principles leads to more modular, readable, and maintainable code, although it may require a shift in mindset from imperative programming practices.
• 🌐 **Community and Tools**: The video script mentions the RUNME extension for VS Code, showcasing the community's efforts to create tools that blend functional programming concepts with practical development environments.

Q & A

What is functional programming?

Functional programming is a paradigm that emphasizes structuring code and ensuring immutability. It revolves around the use of functions in a way where data is immutable and functions aim to have no side effects, making the code more predictable and easier to reason about.

How does functional programming differ from other programming paradigms?

Functional programming differs by focusing on pure functions, immutability, and avoiding side effects, compared to object-oriented programming which organizes code around objects, or procedural programming that structures code as a sequence of steps to be carried out.

What are closures in functional programming?

Closures are functions that can access and remember the scope around them even after the parent function has finished executing. This allows them to capture and maintain any local variables that were in scope at the time of their creation, enabling data encapsulation and higher order functions.

What role do higher-order functions play in functional programming?

Higher-order functions are functions that take other functions as arguments or return them as results. They are crucial in functional programming for creating reusable and modular code, enabling operations like filter, sort, and map, which help write code in a declarative manner.

How does functional programming achieve immutability?

Functional programming achieves immutability by avoiding changes to state or data after its creation. Instead of modifying existing data, operations in a functional paradigm produce new data structures based on existing ones, ensuring that functions have no side effects.

What is currying in functional programming?

Currying is a technique in functional programming where a function with multiple arguments is transformed into a sequence of functions, each with a single argument. This utilizes closures to remember arguments provided in previous calls until all have been supplied, facilitating function composition.

Why would a developer choose the functional programming paradigm?

A developer might choose functional programming to benefit from its emphasis on immutability, pure functions, and avoiding side effects, which can lead to more predictable, readable, and maintainable code. It also helps in writing code that is easier to debug and test.

What are the core values of purely functional programming?

The core values of purely functional programming include declarative and deterministic code that is unchanging, with a strong emphasis on immutability, type safety, and the avoidance of side effects, drawing from mathematical principles to ensure predictability and reliability in code execution.

How does functional programming handle data manipulation?

In functional programming, data manipulation is handled by creating new data structures from existing ones rather than altering the original structures. This is done to maintain immutability and prevent unintended side effects, ensuring that functions always produce the same output for the same input.

What is the significance of the quote 'A closure is a poor man's object, and an object is a poor man's closure'?

This quote highlights the conceptual overlap between closures in functional programming and objects in object-oriented programming. It suggests that closures can encapsulate data and functionalities similar to objects, and vice versa, each serving as a fundamental tool in their respective paradigms for managing state and behavior.

Outlines

00:00

🌟 Introduction to Functional Programming

This paragraph introduces the concept of functional programming, a paradigm that many use without realizing it. It emphasizes the importance of structuring code with immutability and avoiding side effects, akin to a pure mathematical world. The video aims to explore what differentiates functional programming from other paradigms like object-oriented or procedural programming. It explains the idea of a programming paradigm using the metaphor of a tree, showing how languages branch into families. The paragraph outlines the two main branches of imperative and declarative paradigms, moving towards more specific paradigms like functional. It highlights the core elements of functional programming, such as the use of functions, closures, higher-order functions, immutability, and the concept of currying. The explanation includes a brief code example to illustrate closures and their memory capabilities.

05:03

🔄 Utilizing Functional Features and Pure Functional Concepts

This paragraph delves into the application of functional programming features, such as higher-order functions, immutability, and closures, to create reusable and maintainable code. It discusses how these features can be used to build isolated modules and avoid side effects, leading to pure functions. The concept of currying is introduced, explaining how it chains multiple arguments into separate function calls. The paragraph also touches on the idea of using closures to mimic object-oriented programming, encapsulating data and state. It mentions memoization as a technique for storing pre-computed results and the potential challenges of adopting a purely functional approach. The paragraph concludes by highlighting the benefits of functional programming, such as improved data handling, readability, and modularity, while acknowledging the learning curve and optimization challenges.

10:08

🎥 Video Sponsor and Closing Remarks

The final paragraph of the script acknowledges the sponsor of the video, RunMe, and provides an overview of their offering—a free, open-source extension for VS Code that transforms markdown files into interactive notebooks. This tool is beneficial for Development and DevOps, allowing users to run terminal commands and code snippets within documentation. The script praises the flexibility and power of RUNME, which is driven by a separate executable. It encourages viewers to visit the sponsor's website and engage with their community. The video concludes with a personal reflection on the value of learning about functional programming and an invitation for viewers to explore the paradigm further, regardless of their background.

Keywords

💡Functional Programming

Functional programming is a programming paradigm that emphasizes the use of pure functions, immutability, and the avoidance of side effects. It is a way of structuring code that is inspired by mathematical concepts, focusing on what needs to be accomplished rather than how to accomplish it. In the video, functional programming is contrasted with other paradigms like imperative and object-oriented programming, highlighting its unique approach to problem-solving and code organization.

💡Immutability

Immutability refers to the property of data that cannot be changed after it is created. In the context of functional programming, it is a core concept that helps to avoid side effects and ensures that functions are pure, meaning that the same input will always produce the same output without any external influence. The video explains that by enforcing immutability, code becomes more predictable and easier to reason about, as changing data is a common source of bugs and complexity.

💡Pure Functions

Pure functions are a key aspect of functional programming. They are functions that do not have any side effects and whose return value depends only on their input arguments. This means that given the same input, a pure function will always produce the same output. The video emphasizes the importance of pure functions in creating reliable and reusable code, as they make it easier to understand and predict the behavior of the code, which is crucial for maintaining large and complex software systems.

💡Closures

Closures are functions that capture and remember the environment in which they were created. They have access to the parent function's scope, even after the parent function has finished executing. This allows closures to remember and manipulate data from their creation context, which can be useful for maintaining state in a functional programming context. The video uses closures to illustrate how data can be encapsulated and accessed in a way that resembles object-oriented programming, but within the functional paradigm.

💡Higher-Order Functions

Higher-order functions are functions that take other functions as arguments or return them as results. This concept is central to functional programming as it allows for the creation of reusable and composable functions that can operate on other functions. In the video, examples of higher-order functions include common utilities like filter(), sort(), and map(), which are used to transform and manipulate data in a declarative manner, promoting a more modular and maintainable codebase.

💡Side Effects

Side effects are actions or changes that occur outside the local scope of a function and can affect the state of the system or other parts of the code. In functional programming, minimizing or eliminating side effects is important to ensure that functions are pure and that the behavior of the code is predictable and consistent. The video explains that by avoiding side effects, developers can write code that is easier to test, debug, and maintain.

💡Currying

Currying is a technique in functional programming where a function that takes multiple arguments is transformed into a sequence of functions that each take a single argument. This allows for the partial application of functions, where some arguments are fixed and others can be supplied later. The video mentions currying as a way to structure and chain function calls, leveraging the memory capabilities of closures to create flexible and reusable functions.

💡Declarative Programming

Declarative programming is a paradigm that focuses on describing the desired outcome or goal of a computation without explicitly specifying the steps to achieve it. This is in contrast to imperative programming, which involves giving detailed instructions on how to perform the task. The video positions functional programming as a type of declarative programming, emphasizing the 'what' over the 'how', which can lead to more readable and maintainable code.

💡First-Class Functions

First-class functions are functions that are treated as first-class citizens by the programming language, meaning they can be assigned to variables, passed as arguments, and returned from other functions, just like any other data type. This is a fundamental concept in functional programming, as it enables the creation of higher-order functions and the use of functions as building blocks for more complex operations. The video highlights the importance of first-class functions in making functional programming flexible and powerful.

💡Memoization

Memoization is an optimization technique used to speed up computer programs by storing the results of expensive function calls and returning the cached result when the same inputs occur again. In the context of functional programming, closures can be used to store these results privately, allowing for efficient reuse of computations. The video briefly mentions memoization as one of the practical applications of closures, demonstrating how functional techniques can lead to performance improvements.

Highlights

Functional programming is a paradigm often used without awareness, focusing on the structure of code and the concept of immutability.

Programming paradigms are like a tree, branching into different families similar to spoken languages, with the two biggest branches being imperative and declarative.

Functional programming is situated halfway down the declarative branch, emphasizing the use of functions and immutability.

Functions in functional programming should be first-class citizens, meaning they can be passed around, returned from, and held as references.

Closures are functions that can access and remember their surrounding scope, even after the parent function has finished executing.

Closures can be nested within each other, allowing access to data several layers deep in the function hierarchy.

Higher-order functions are a key concept in functional programming, allowing functions to work with other functions to perform actions like filtering and mapping.

Immutability in functional programming aims to minimize side effects, making functions pure and ensuring the same output for the same input.

Closures can encapsulate data and state, acting as a poor man's object in the context of functional programming.

Currying is a functional programming technique that involves breaking down a function with multiple arguments into a sequence of functions each with a single argument.

Functional paradigm promotes declarative, deterministic, and unchanging code, which aligns with mathematical principles.

In purely functional programming, code is evaluated rather than executed, allowing for optimizations like lazy evaluation and automatic parallelization.

Functional programming, while potentially more challenging to optimize, leads to highly modular and maintainable code.

Learning functional programming techniques, even if not fully adopted, can improve a programmer's overall coding skills and understanding.

The video sponsor, RunMe, offers an open-source extension for VS Code that turns markdown files into interactive notebooks.

RUNME's core functionality is powered by a separate executable, providing flexibility for various use cases including terminal use and automation.

The video encourages keeping an open mind and continuous learning, regardless of one's programming background or preferred paradigm.

Transcripts

If you've heard the words functional programming, you might think it has something to do with functions, and you'd be right.

Functional programming is a paradigm a lot of us use all the time, and maybe don't even know it.

It's about the way we structure our code and the immutability of a pure, yet somewhat impractical world.

It's about math and equations and side effects, and it even comes with some delicious curry.

So, let's take a look at what may make functional different from the way you've been programming so far.

What exactly is a programming paradigm, then?

Well, to answer that, I give you a tree.

It's a special tree, though.

One that we can use to show how programming languages branch into different families, just like spoken languages.

Looking at the two biggest branches, we have imperative, or the paradigm of giving explicit instructions.

Basically, the how.

And declarative, or the paradigm of describing our goal.

Basically, the what.

As we go down each branch, we go from more generic programming paradigms to more specific ones.

Each programming language you will use follows a recipe of one or more available programming paradigms.

And in reality, a lot more paradigms exist than the two branches I've just mentioned.

About halfway down the declarative branch, we have the functional paradigm,

which outlines the common concepts or styles behind what makes functional programming unique

when compared with other common paradigms such as object-oriented or procedural.

At the core of the functional paradigm, we have functions, obviously.

And these functions need to be usable in a fairly unrestricted way,

meaning we can pass them to other functions and return them from other functions,

as well as hold references to them for later use.

We also need to be able to create closures, which are functions that can access and remember the scope around them.

In a typical function stack, the scope of a function is forgotten when leaving it.

But when a closure is created, that scope stays in memory for as long as the closure still exists.

This means that we can return a closure from a parent function

and still have access to all the arguments and data that the parent function also had access to,

even if we call the closure from a completely different scope later on.

Hey, it's me from the future.

I realized that closures might need a bit more explanation, so here's some code to help.

We can see that closures are just simple anonymous functions that we define inside of other functions.

What makes closures special, though, is the fact that they can always access the data of the parent function that created them,

even if we return them and that parent function goes away.

Because they can always access their parent scope like this,

we can go crazy and put closures inside of closures to access all the way back to the function that originally created the first one.

And we'll use this concept later on in the video.

Their ability to store data in this way means that closures are sometimes described using this quote that I think might help the OO programmers.

"A closure is a poor man's object...

...and an object is a poor man's closure."

Anyway, let's get back to it.

How can we use these features in a functional way?

We can start by creating some higher order functions,

which are functions that work with other functions to basically perform an action.

Think filter(), sort(), map(), and so on.

These help us to create reusable and isolated modules

that we can compose together to write our code more declaratively.

Next we have immutability, where we aim to avoid something called side effects.

Side effects happen when we allow unpredictable state from outside the scope of a function to affect it in some way,

or when we allow a function to make changes outside of its scope.

In getting rid of potential side effects, our functions become pure,

in that if the same data goes into a function, we can always guarantee the same result coming out, without affecting anything else.

This is typically enforced by removing the variability of variables.

Lastly, we can use closures as a way to encapsulate data and state.

There's an important concept in functional programming called currying.

I told you there'd be curry.

Currying brings up multiple arguments of a function into their own function calls that we then chain together.

It achieves this using the scope memory ability of closures,

where each argument will stay in memory until the chain completes, and we get our result.

In a similar way, we can use closures to create something resembling an object.

The first function in the chain acts as a kind of object constructor,

and would be where we define most of our internal data.

This data is privately scoped to the constructor function, and therefore encapsulated by it.

We can then return a closure to provide external access to this private data.

This can be used for simple tasks, such as pre-computing and storing the result of expensive operations,

something we call memoization.

Or we can go as far as returning multiple named closures to access and manipulate the internal data in more complex ways,

further solidifying it in its object-like behaviors.

Anyway, these are just techniques that we use in the functional paradigm.

We haven't yet really inspected the core values of what it means to be purely functional.

We enter a world where everything is declarative, deterministic, and ideally unchanging, pretty much forever.

While that may not sound very useful on the surface, it has its roots in the mathematical world, and there it actually makes a lot of sense.

In the purely functional paradigm, we work primarily with types and expressions, where the following rules apply:

Code is generally evaluated rather than executed, which gives us some interesting new optimization abilities,

such as lazy evaluation and automatic parallelization.

Immutability is enforced everywhere, meaning that when we want to make changes to our data,

we do so by computing a new constant based off of an existing constant.

And to keep functions pure, the mere thought of a side effect is punishable by the most horrific torture imaginable.

Having to learn...

MONADS!

Now, this (purely functional) world is beautiful, but it's really not for the faint of heart.

And so most of us mortal programmers just take the smallest fruits hanging from the purely functional branch, and we try to use them as best we can.

With all these differences in mind, why would we use the functional paradigm?

Well, there's actually many benefits to it.

The immutability of the functional paradigm forces us to think more strictly about how we pass data around,

helping to ensure that changes don't happen unexpectedly.

It also guides us in forming readable code that's highly modular and therefore maintainable.

It does come at the cost of potentially being a bit harder to optimize though, depending on where in the branch you're using functional,

and can be a bit of a challenge to transition to a more declarative approach if you're already used to imperative styles of programming.

Anyway, whether you consider yourself a functional programmer, object-oriented programmer, or just like the basic simplicity of procedural code,

always keep an open mind and never be scared to learn more.

Even if you don't end up using functional, learning something new is never a waste of time.

I'd like to finish by thanking the sponsor of this video, RunMe.

They're offering a completely free and open source extension for VS Code that turns your basic markdown files into fully interactive notebooks

where you can run terminal commands or code snippets, then view the results without ever leaving the documentation you're in.

Now this is really great for Development and DevOps, where you can test out snippets of code or document and share workflows with the rest of the team.

What's more, all of the core functionality of RUNME is actually powered by a separate executable,

which you can interact with in all of the same ways as you can in VS Code.

What this means is you get some power and flexibility.

You can use RUNME however you want, whether it's your favorite terminal, third-party integration, or in an automation such as your build pipeline.

Anyway, the team are really nice people, and they're looking for your input to make this a really great product.

So go to RUNME.dev, check it out, and visit their Discord to get involved.

Thank you for watching, and I'm so sorry it took so long to make this video.

I really wanted it to be right, not rushed, so I ended up rewriting it a lot before finding a satisfactory way to tell the functional story.

Honestly, I've really loved learning more about the functional paradigm, especially the pure side.

It's complex, but fascinating at the same time, and I'd highly recommend diving into it yourself, no matter your background.

I hope you enjoyed it, and as always, I'll see you next time.