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71 lines
3.0 KiB
Markdown
71 lines
3.0 KiB
Markdown
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Introducing Swift on Fedora
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======
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Swift is a general-purpose programming language built using a modern approach to safety, performance, and software design patterns. It aims to be the best language for a variety of programming projects, ranging from systems programming to desktop applications and scaling up to cloud services. Read more about it and how to try it out in Fedora.
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### Safe, Fast, Expressive
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Like many modern programming languages, Swift was designed to be safer than C-based languages. For example, variables are always initialized before they can be used. Arrays and integers are checked for overflow. Memory is automatically managed.
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Swift puts intent right in the syntax. To declare a variable, use the var keyword. To declare a constant, use let.
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Swift also guarantees that objects can never be nil; in fact, trying to use an object known to be nil will cause a compile-time error. When using a nil value is appropriate, it supports a mechanism called **optionals**. An optional may contain nil, but is safely unwrapped using the **?** operator.
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Some additional features include:
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* Closures unified with function pointers
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* Tuples and multiple return values
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* Generics
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* Fast and concise iteration over a range or collection
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* Structs that support methods, extensions, and protocols
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* Functional programming patterns, e.g., map and filter
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* Powerful error handling built-in
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* Advanced control flow with do, guard, defer, and repeat keywords
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### Try Swift out
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Swift is available in Fedora 28 under then package name **swift-lang**. Once installed, run swift and the REPL console starts up.
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```
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$ swift
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Welcome to Swift version 4.2 (swift-4.2-RELEASE). Type :help for assistance.
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1> let greeting="Hello world!"
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greeting: String = "Hello world!"
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2> print(greeting)
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Hello world!
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3> greeting = "Hello universe!"
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error: repl.swift:3:10: error: cannot assign to value: 'greeting' is a 'let' constant
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greeting = "Hello universe!"
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~~~~~~~~ ^
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3>
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```
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Swift has a growing community, and in particular, a [work group][1] dedicated to making it an efficient and effective server-side programming language. Be sure to visit [its home page][2] for more ways to get involved.
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Photo by [Uillian Vargas][3] on [Unsplash][4].
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--------------------------------------------------------------------------------
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via: https://fedoramagazine.org/introducing-swift-fedora/
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作者：[Link Dupont][a]
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选题：[lujun9972](https://github.com/lujun9972)
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译者：[译者ID](https://github.com/译者ID)
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校对：[校对者ID](https://github.com/校对者ID)
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本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
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[a]: https://fedoramagazine.org/author/linkdupont/
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[1]: https://swift.org/server/
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[2]: http://swift.org
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[3]: https://unsplash.com/photos/7oJpVR1inGk?utm_source=unsplash&utm_medium=referral&utm_content=creditCopyText
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[4]: https://unsplash.com/search/photos/fast?utm_source=unsplash&utm_medium=referral&utm_content=creditCopyText
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