Re: Functional Programming In Swift Ebook Pdf Download
Dwaine Hawke
I always thought functions and methods were the same, until I was learning Swift through the "Swift Programming Language" eBook. I found out that I cannot use greet("John", "Tuesday") to call a function that I declared inside a class, as shown in the eBook in the screen shot below:
After some research, I found this post: Difference between a method and a function, and it seems to me that the function that I declared inside a class is actually called a method. So, the syntax that I use to call the method is different compared to the syntax that I use to call a function.
Methods are functions that are associated with a particular type. Classes, structures, and enumerations can all define instance methods, which encapsulate specific tasks and functionality for working with an instance of a given type.
Specifically, Swift gives the first parameter name in a method a local parameter name by default, and gives the second and subsequent parameter names both local and external parameter names by default.
As you said yourself, methods are functions, but in a class. In objective-c you never realized this, because we were only coding in classes. Every function that we wrote was a method of a class (ViewController or some other class we created).
In Swift we have the ability to create functions that are not inside some class. The main reason for doing this is to write functions that are not tied to any class, and can be used wherever we need them. So if you have a function that is related to a class you write it inside the class and you can access is from every instance of the class:
About your syntax issues between functions and methods: You guessed it right, methods and functions are called a little bit differently. That is because in Objective-C we had long method names and we liked them because we could read what the methods were doing and what the parameters were for. So the first parameter in a method is in most cases described by the function name itself. And the other parameters shouldn't only be some numbers or strings or instances, they should be described as well, so Swift writes the name of the variable automatically. If you want to describe it by yourself you can do that as well:
someMethod works only on its associated type which is 'someClass'. However the same can't be said for someFunc. someFunc is only in the someClass.Swift because semantically it is better suited to be written in that file. It could have been written in any other class as long as it's marked with private
Closure(closure expression) - anonymous function - is a block of code(functionality). Closure is a type of function without name. Closure is a function in terms of Functional programming. It can support capturing concept(if it doesn't capture it is lambda). It is similar to block in Objective-C.
See how Swift, the development language for iOS, encourages you to buildhighly scalable apps using functional techniques like map and reduce.Discover how Scala allows you to transition gently but deeply intofunctional programming without losing the benefits of the JVM, whilewith Lisp-based Clojure, you can plunge fully into the functional style.Learn about advanced functional concepts in Haskell, a pure functionallanguage making powerful use of the type system with type inference andtype classes. And see how functional programming is becoming moreelegant and friendly with Elixir, a new functional language built on thepowerful Erlang base.
A: PragPub is a monthly magazine by and for software developers that Icreated in 2009 for the Pragmatic Programmers. It began as a showcasefor the authors of their books, and has evolved into an independentpublication. But we still have a close relationship with the PragmaticProgrammers, and we still feature many of their authors. This book, forexample, includes chapters by Stuart Halloway, Venkat Subramaniam, andDave Thomas, all of whom have written well-received books on thesubjects they write about in this book.
This book explains how you could use functional programming to improve on what you do. The authors did not engage much in theory, however, they proceeded by examples to explain different aspects of functional programming.
I set my eyes on this book when it was announced, in hopes to find the answers for two questions:
1. What are the core principles of functional programming? What factors can be used to judge a piece of code to adhere to functional programming well?
2. Why should someone switch to / adopt more functional programming?
Despite being referenced many times in the book, both questions were not its main focus. The book focuses on teaching you how to leverage functional programming for the benefit of your programming skills, while using Swift. So the book is most perfect for people who are not waiting for a theoretical approach on the subject, but who are open-minded enough to mix different paradigms and ideas in their practices.
I can safely claim that Swift was designed from day one to fully embrace functional programming, and it's comfortably sitting in the that suite behind Haskell along with Scala, F#, OCaml and their sisters. You can go fully functional with it, or you can easily mix it with OOP. Or you could just ignore everything sweet Swift has to offer and just write Objective-C without semicolons.
I'm currently in the midst of a storm, trying to wrap my head around FP, OOP and the right ways to mix both. Some of the FP purists abhor OOP, and declare it the next worst thing after Nazis. As I myself am evolving in OOP, and have just started to understand its principles well, despite having spent almost 8 years in the industry divided between college and work. I can boldly claim that a lot of people don't understand a nickle about what OOP is about. While one of the perks of FP having little following compared to imperative and object-oriented languages, is that it hasn't been plagued with bad practices yet.
In conclusion, I think it's possible to mix FP and OOP in practice. Martin Odersky's Functional Programming Principles in Scala gives some good insight in that.
While user defaults is convenient for persisting simple bits of state, more complex data types should be saved to the file system. This can be tricky to get right, and so we take the time to properly handle all of the edge cases.
We can now persist simple bits of state to user defaults using the @Shared property wrapper, but there is more work to be done. We need to observe changes to user defaults in order to play those changes back to @Shared, and we need to put in a bit of extra work to make everything testable.
We finish building a complex, flow-based case study that leverages the new @Shared propertywrapper. Along the way we will flex recently added superpowers of the library, and we willexperience firsthand how simple this new model of shared state can be.
To celebrate our 6th anniversary we had another livestream! We updated an app from the mostrecent Composable Architecture tour to the latest observation tools, showed how these toolscan improve UIKit-based apps, showed off some recent enhancements to the @Reducer macro,gave a sneak peek of a highly anticipated topic, and answered your questions along the way.
We have iterated on how bindings work in the Composable Architecture many times, but havenever been fully happy with the results. With Observation, that all changes. By eliminatingview stores and observing store state directly, we are free to totally reimagine bindings inthe Composable Architecture, and get rid of even more concepts in the process.
While the @Observable macro improves upon nearly every aspect of the @State and @ObservedObject property wrappers, it is not without its pitfalls. We will explore several gotchas that you should be aware of when adopting observation in your applications.
The @Observable macro is here and we will see how it improves on nearly every aspect of the old tools in SwiftUI. We will also take a peek behind the curtain to not only get comfortable with the code the macro expands to, but also the actual open source code that powers the framework.
We show how to add stack-based navigation to a Composable Architecture application, how tosupport many different kinds of screens, how to deep link into a navigation stack, and how towrite deep tests for how navigation is integrated into the application.
We enhance our navigation stack with a bit more complexity by adding the ability to drill down multiple layers in multiple ways: using the new navigation link API, and programmatically. We also prepare a new feature to add to the stack.
Our first ever livestream! We talk about a few new features that made it into ourDependencies library when we extracted itfrom the Composable Architecture, live code our way through a NavigationStack refactor ofour Standups app, and answer your questions alongthe way!
When all-new SwiftUI navigation tools were announced at WWDC, the one that got the most attention by far was NavigationStack, which powers navigation with an array. It is extremely powerful, but comes with trade-offs and new complexities.
Testing is a top priority in the Composable Architecture, so what does the reducer protocoland new dependency management system add to testing features? It allows us to codify a testingpattern directly into the library that makes our tests instantly stronger and more exhaustive.
We are already seeing huge benefits from the reducer protocol, but one aspect is still not ideal, and that is how we compose reducers. We will look to result builders to solve the problem, and a new feature of them introduced in Swift 5.7.
We explore ways to tie the lifetime of an effect to the lifetime of a view, making it possible to automatically cancel and tear down work when a view goes away. This unexpectedly helps us write even stronger tests for our features.
We conclude our tour of swift-parsing with a look at how URL routers defined as parser-printers can be automatically transformed into fully-fledged API clients, which we will drop into an iOS application and immediately use.
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