1.安装Java
按照最全的步骤进行，JAVA_HOME, CLASSPATH, path的设置，简记如下：
（1）下载之后默认安装即可。注意：安装的时候记住你的安装路径。
例如我这里的安装路径是：C:\Program Files\Java\jdk1.8.0_171
（2）新建JAVA_HOME系统变量 变量名：JAVA_HOME ，变量值：C:\Program Files\Java\jdk1.8.0_171
（3）新建CLASSPATH变量 变量名：CLASSPATH , 变量值： .;%JAVA_HOME%\lib;%JAVA_HOME%\lib\tools.jar
（4）配置系统环境变量Path 双击Path-->新建-->添加“%JAVA_HOME%\bin”-->将这一行变量上移到最顶端-->完成
（5）应用所有环境变量配置完成之后，应用环境变量即可。
（6）测试：win+R弹出运行窗口后，输入cmd，回车弹出命令行窗口，分别输入"java -version"、"javac"
2.安装
2.1 安装Scala，
（1）下载网址https://www.scala-lang.org/download/
（2）单击Download the Scala binaries for windows 保存下载二进制文件
（3）下载完毕后，双击安装，注意修改安装位置为D:\Scala，否则报错。
（4）安装完毕后即可在cmd中输入scala启动命令行解释器。
2.2 sbt的安装配置
(1)安装
如果使用sbt来编译scala项目，上面的安装scala可以忽略，sbt会自动下载scala所有相关内容，于手动安装的scala是独立的。
除了按照这个安装步骤执行之外，在该步骤中间插入一个配置步骤：
不要采用默认的安装路径（C:/D:\Program File...），而是假设sbt安装在了D:\sbt\路径
在运行任何的sbt命令之前，
https://docs.scala-lang.org/getting-started/sbt-track/getting-started-with-scala-and-sbt-on-the-command-line.html
(2)配置 ：增加一个文件，编辑一个文件。
第一步：增加如下 D:/sbt/conf/repo.properties
文件内容为：
[repositories] local aliyun-central: https://maven.aliyun.com/repository/central aliyun-public: https://maven.aliyun.com/repository/public sbt-plugin: https://repo.scala-sbt.org/scalasbt/sbt-plugin-releases/, [organization]/[module]/(scala_[scalaVersion]/)(sbt_[sbtVersion]/)[revision]/[type]s/[artifact](-[classifier]).[ext], bootOnly sbt-plugin-releases2: https://dl.bintray.com/sbt/sbt-plugin-releases/, [organization]/[module]/(scala_[scalaVersion]/)(sbt_[sbtVersion]/)[revision]/[type]s/[artifact](-[classifier]).[ext], bootOnly sonatype: https://oss.sonatype.org/content/repositories/snapshots typesafe: https://repo.typesafe.com/typesafe/ivy-releases/, [organization]/[module]/(scala_[scalaVersion]/)(sbt_[sbtVersion]/)[revision]/[type]s/[artifact](-[classifier]).[ext], bootOnly typesafe2: https://repo.typesafe.com/typesafe/releases/ jcenter: https://jcenter.bintray.com/ repo1: https://repo1.maven.org/maven2/ store_2: https://repo2.maven.org/maven2/ aliyun-releases: https://maven.aliyun.com/repository/releases aliyun-jcenter: https://maven.aliyun.com/repository/jcenter第二步：编辑文件 D:/sbt/conf/sbtconfig.txt
内容修改为：
# sbt configuration file for Windows # Set the java args #-mem 1024 was added in sbt.bat as default -Xms1024m -Xmx1024m -Xss4M -XX:ReservedCodeCacheSize=128m # Set the extra sbt options -Dsbt.log.format=true -Dsbt.boot.directory=D:/sbt/boot/ -Dsbt.global.base=D:/sbt/.sbt -Dsbt.ivy.home=D:/sbt/.ivy2 -Dsbt.repository.config=D:/sbt/conf/repo.properties -Dsbt.override.build.repos=true倒数第二项的文件名跟第一步中添加的文件相同。
其他部分不用预设，直接按照官方步骤开始运行含sbt的命令，比如sbt run之类的。第一次编译会现在很多文件，网路比较慢，系统会缓存下来，以后就快了。
若使用IntelliJ Idea，可参考如下文章：
https://blog.csdn.net/godenbird312/article/details/103787144
3. 测试安装效果，
《Scala编程》代码网址：
https://www.cs.helsinki.fi/u/wikla/OTS/Sisalto/examples/index.html
简单测试：
以下都是直接使用Scala命令行工具直接编译运行的方式：
在E:\的空闲目录保存如下内容至文件 functionValue_9_1.scala中：
object FileMatcher{ private def filesHere = (new java.io.File(".")).listFiles private def filesMatching(query: String, matcher: (String, String)=> Boolean) = { for(file <- filesHere; if matcher(file.getName, query)) yield file } /* def filesEnding(query: String) = filesMatching(query, (x:String, y:String) => x.endsWith(y)) */ def filesEnding(query: String)= filesMatching( query, _.endsWith(_) ) /* def filesContaining(query: String) = filesMatching(query, (x:String, y:String) => x.contains(y)) */ def filesContaining(query: String)= filesMatching(query,_.contains(_)) /* def filesRegex(query: String) = filesMatching(query, (x:String, y:String) => x.matches(y)) */ def filesRegex(query: String) = filesMatching(query, _.matches(_)) } FileMatcher.filesEnding(".scala").foreach(println) //FileMatcher.filesContaining("Lines").foreach(println) //FileMatcher.filesRegex("(.*)Li(.*)").foreach(println)
并在CMD Console 中cd至刚刚保存的Scala源文件目录中，并执行：
scala functionValue_9_1.scala
应该打印出类似如下一行
.\functionValue_9_1.scala
同样的功能，也可以使用下面这段，体现了闭包化简思路：
object FileMatcher{ private def filesHere = (new java.io.File(".")).listFiles private def filesMatching( matcher: (String)=> Boolean) = { for(file <- filesHere; if matcher(file.getName)) yield file } /* def filesEnding(query: String) = filesMatching( (fileName:String) => fileName.endsWith(query)) */ def filesEnding(query: String) = filesMatching( _.endsWith(query)) /* def filesContaining(query: String) = filesMatching((fileName:String) => fileName.contains(query)) */ def filesContaining(query: String) = filesMatching(_.contains(query)) def filesRegex(query: String) = filesMatching( (fileName:String) => fileName.matches(query)) /* def filesRegex(query: String) = filesMatching(query, _.matches(_)) */ } //FileMatcher.filesEnding(".scala").foreach(println) //FileMatcher.filesContaining("Lines").foreach(println) FileMatcher.filesRegex("(.*)Li(.*)").foreach(println)
柯里化的示例：
import java.io.File import java.io.PrintWriter def withPrintWriter(file: File)(op: PrintWriter => Unit)={ val writer = new PrintWriter(file) try{ op(writer) }finally{ writer.close() } } withPrintWriter(new File("logL3.txt")){_.println("hello")}
保存这段代码，并且运行：scala 文件名.scala
object Element { private class ArrayElement( val contents: Array[String] ) extends Element private class LineElement(s: String) extends Element { val contents = Array(s) override def width = s.length override def height = 1 } private class UniformElement( ch: Char, override val width: Int, override val height: Int ) extends Element { private val line = ch.toString * width def contents = Array.fill(height)( line) } def elem(contents: Array[String]): Element = new ArrayElement(contents) def elem(chr: Char, width: Int, height: Int): Element = new UniformElement(chr, width, height) def elem(line: String): Element = new LineElement(line) } /// import Element.elem abstract class Element { def contents: Array[String] def width: Int = contents(0).length def height: Int = contents.length def above(that: Element): Element = { val this1 = this widen that.width val that1 = that widen this.width elem(this1.contents ++ that1.contents) } def beside(that: Element): Element = { val this1 = this heighten that.height val that1 = that heighten this.height elem( for ((line1, line2) <- this1.contents zip that1.contents) yield line1 + line2) } def widen(w: Int): Element = if (w <= width) this else { val left = elem(' ', (w - width) / 2, height) var right = elem(' ', w - width - left.width, height) left beside this beside right } def heighten(h: Int): Element = if (h <= height) this else { val top = elem(' ', width, (h - height) / 2) var bot = elem(' ', width, h - height - top.height) top above this above bot } override def toString = contents mkString "\n" } // //package org.stairwaybook.expr import Element.elem sealed abstract class Expr case class Var(name: String) extends Expr case class Number(num: Double) extends Expr case class UnOp(operator: String, arg: Expr) extends Expr case class BinOp(operator: String, left: Expr, right: Expr) extends Expr class ExprFormatter { // Contains operators in groups of increasing precedence private val opGroups = Array( Set("|", "||"), Set("&", "&&"), Set("^"), Set("==", "!="), Set("<", "<=", ">", ">="), Set("+", "-"), Set("*", "%") ) // A mapping from operators to their precedence private val precedence = { val assocs = for { i <- 0 until opGroups.length op <- opGroups(i) } yield op -> i Map() ++ assocs } private val unaryPrecedence = opGroups.length private val fractionPrecedence = -1 private def format(e: Expr, enclPrec: Int): Element = e match { case Var(name) => elem(name) case Number(num) => def stripDot(s: String) = if (s endsWith ".0") s.substring(0, s.length - 2) else s elem(stripDot(num.toString)) case UnOp(op, arg) => elem(op) beside format(arg, unaryPrecedence) case BinOp("/", left, right) => val top = format(left, fractionPrecedence) val bot = format(right, fractionPrecedence) val line = elem('-', top.width max bot.width, 1) val frac = top above line above bot if (enclPrec != fractionPrecedence) frac else elem(" ") beside frac beside elem(" ") case BinOp(op, left, right) => val opPrec = precedence(op) val l = format(left, opPrec) val r = format(right, opPrec + 1) val oper = l beside elem(" "+ op +" ") beside r if (enclPrec <= opPrec) oper else elem("(") beside oper beside elem(")") } def format(e: Expr): Element = format(e, 0) } / //import org.stairwaybook.expr._ object Express extends App { val f = new ExprFormatter val e1 = BinOp("*", BinOp("/", Number(1), Number(2)), BinOp("+", Var("x"), Number(1))) val e2 = BinOp("+", BinOp("/", Var("x"), Number(2)), BinOp("/", Number(1.5), Var("x"))) val e3 = BinOp("/", e1, e2) def show(e: Expr) = println(f.format(e)+ "\n\n") for ( e <- Array(e1, e2, e3)) show(e) }
保存并运行这段递归插入排序法的代码： scala 文件名.scala
/* def isort(xs: List[Int]):List[Int] = if(xs.isEmpty) Nil else insert(xs.head, isort(xs.tail)) def insert(x: Int, xs: List[Int]): List[Int] = if(xs.isEmpty || x <= xs.head ) x::xs else xs.head:: insert(x, xs.tail) */ def isort(xs: List[Int]):List[Int] = xs match{ case List() => List() case x::xs1 => insert(x, isort(xs1)) } def insert(x: Int, xs: List[Int]): List[Int] = xs match{ case List() => x::List() case y::ys => if(x<=y) x::xs else y::insert(x, ys) } var lx=List(3,8,6,5,2,7) lx = isort(lx) println(lx)
或者：
def append[T](xs: List[T], ys: List[T]): List[T] = xs match{ case List() => ys case x::xs1 => if(xs1.isEmpty) x::ys//为何本行多余？ else x::append(xs1, ys) } var lx=List(2,3,7,4,3) var ly=List(0,4,7,9) println(append[Int](lx, ly))
