如何从命令行运行Scala文件? [英] How to run scala file from command line?

问题描述

scala是否支持 scala run xxx.scala ?go语言支持像

Does scala support scala run xxx.scala? The go language supports running like

go my.go

和python支持

python my.py

但似乎

scala xxx.scala

仅是语法检查，没有观察到输出或运行行为.那么有没有办法直接运行scala文件?

is only a syntax check, no output or running behavior is observed. So is there a way to run a scala file directly?

推荐答案

这似乎很容易.但是您必须使用println来打印某些内容.

It seems pretty easy. But you have to use println to print something.

➜  ~ cat hello.scala
println("hello, world")
➜  ~ scala hello.scala
hello, world
➜  ~ scala -Vprint:parser hello.scala
[[syntax trees at end of                    parser]] // hello.scala
package <empty> {
  object Main extends scala.AnyRef {
    def <init>() = {
      super.<init>();
      ()
    };
    def main(args: Array[String]): scala.Unit = {
      final class $anon extends scala.AnyRef {
        def <init>() = {
          super.<init>();
          ()
        };
        println("hello, world")
      };
      new $anon()
    }
  }
}

hello, world
➜  ~ 

或者有几种方法可以将行输入到REPL，为您打印结果.

or there are a few ways to feed lines to the REPL, which prints results for you.

➜  ~ cat calc.scala
2 + 2
➜  ~ scala < calc.scala
Welcome to Scala 2.13.1 (OpenJDK 64-Bit Server VM, Java 11.0.3).
Type in expressions for evaluation. Or try :help.

scala> 2 + 2
res0: Int = 4

scala> :quit
➜  ~ 

另请参见 -i ， -I ， -e 和:load 和:paste 命令.

See also -i, -I, -e, and the :load and :paste commands.

如另一个答案所示，它还将在对象中寻找Java风格的main方法.通常，这就是编译程序入口点的方式.

As shown in the other answer, it will also look for a Java-style main method in an object. That's how you'd normally compile a program entry point.

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