如何使用swift函数式编程

本篇内容主要讲解"如何使用swift函数式编程"，感兴趣的朋友不妨来看看。本文介绍的方法操作简单快捷，实用性强。下面就让小编来带大家学习"如何使用swift函数式编程"吧!

示例

//统计词频let non_words: Set = ["the", "and", "of", "to", "a", "i", "it", "in", "or", "is", "as", "so", "but", "be", "don't"]//常规方式func wordFreq(words: String) -> [Dictionary] {    var wordDict : [String: Int] = [:]    let wordList = words.split(separator: " ")    for word in wordList {        let lowerCaseWord = word.lowercased()        if !non_words.contains(lowerCaseWord) {            if let count = wordDict[lowerCaseWord] {                wordDict[lowerCaseWord] = count + 1            } else {                wordDict[lowerCaseWord] = 1            }        }    }    var sortedResult = [Dictionary]()    for item in wordDict.sorted { $0.1 > $1.1 } {        sortedResult.append([item.key: item.value])    }    return sortedResult}let words = """The powerful programming language that is also easy to learn Swift is a powerful and intuitive programming language for macOS iOS watchOS tvOS and beyond Writing Swift code is interactive and fun the syntax is concise yet expressive and Swift  includes  modern features developers love Swift code is safe by design yet also produces software that runs lightning-fast Swift is the result of the latest research on programming languages combined with decades of experience building Apple platforms Named parameters are expressed in a clean syntax that makes  APIs"""let ret = wordFreq(words: words)print(ret)//[["swift": 5], ["programming": 3], ["that": 3], ["syntax": 2], ["code": 2], ["yet": 2], ["powerful": 2], ["also": 2], ["language": 2], ["beyond": 1], ["clean": 1], ["result": 1], ["features": 1], ["on": 1], ["produces": 1], ["concise": 1], ["latest": 1], ["developers": 1], ["for": 1], ["design": 1], ["experience": 1], ["with": 1], ["parameters": 1], ["building": 1], ["macos": 1], ["combined": 1], ["languages": 1], ["lightning-fast": 1], ["tvos": 1], ["interactive": 1], ["safe": 1], ["fun": 1], ["apis": 1], ["easy": 1], ["decades": 1], ["makes": 1], ["by": 1], ["includes": 1], ["expressed": 1], ["love": 1], ["are": 1], ["intuitive": 1], ["named": 1], ["research": 1], ["writing": 1], ["watchos": 1], ["expressive": 1], ["apple": 1], ["platforms": 1], ["learn": 1], ["ios": 1], ["software": 1], ["modern": 1], ["runs": 1]]//函数式编程方式func wordFreqTwo(words: String) -> [Dictionary] {    var wordDict: [String: Int] = [:]    words.split(separator: " ")        .map{ $0.lowercased() }        .filter{ !non_words.contains($0) }        .forEach{ (word) in            wordDict[word] = (wordDict[word] ?? 0) + 1        }    var sortedResult = [Dictionary]()    wordDict.sorted{ $0.1 > $1.1 }        .forEach{ (word) in            sortedResult.append([word.key: word.value])        }    return sortedResult}let retTwo = wordFreqTwo(words: words)print(retTwo)//[["swift": 5], ["programming": 3], ["that": 3], ["syntax": 2], ["also": 2], ["language": 2], ["powerful": 2], ["yet": 2], ["code": 2], ["love": 1], ["safe": 1], ["watchos": 1], ["ios": 1], ["combined": 1], ["tvos": 1], ["runs": 1], ["are": 1], ["experience": 1], ["design": 1], ["by": 1], ["expressed": 1], ["features": 1], ["result": 1], ["parameters": 1], ["expressive": 1], ["building": 1], ["fun": 1], ["software": 1], ["on": 1], ["research": 1], ["writing": 1], ["produces": 1], ["with": 1], ["clean": 1], ["platforms": 1], ["named": 1], ["concise": 1], ["latest": 1], ["makes": 1], ["interactive": 1], ["languages": 1], ["easy": 1], ["for": 1], ["lightning-fast": 1], ["beyond": 1], ["decades": 1], ["apis": 1], ["learn": 1], ["includes": 1], ["modern": 1], ["apple": 1], ["macos": 1], ["intuitive": 1], ["developers": 1]]

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