How do I get "sbt hello, world" to run?

Question

I'm trying to get a clue about Scala/SBT and was walking through http://www.scala-sbt.org/0.13/docs/Hello.html

The first step went well...I've got a directory called "hello" that has the result of $ sbt new sbt/scala-seed.g8 in it.

At the 2nd step, "Running your app", the wheels come off.

$ sbt
[info] Loading project definition from /Users/robert.kuhar/dev/Hello/project
[info] Set current project to Hello (in build file:/Users/robert.kuhar/dev/Hello/)
> run
[info] Compiling 1 Scala source to /Users/robert.kuhar/dev/Hello/target/scala-2.12/classes...
[info] 'compiler-interface' not yet compiled for Scala 2.12.1. Compiling...
[info] Resolving org.scala-sbt#interface;0.13.13 ...
[trace] Stack trace suppressed: run last compile:compileIncremental for the full output.
[error] (compile:compileIncremental) java.lang.reflect.InvocationTargetException
[error] Total time: 1 s, completed Mar 9, 2017 3:34:03 PM
>

The output of the run last compile:compileIncremental is greek to the eyes of a noobie...

...
[info] Resolving org.scala-sbt#interface;0.13.13 ...
java.lang.VerifyError: Uninitialized object exists on backward branch 209
Exception Details:
  Location:
    scala/collection/immutable/HashMap$HashTrieMap.split()Lscala/collection/immutable/Seq; @249: goto
  Reason:
    Error exists in the bytecode
...

I'm off the track, in the weeds, and in search of a clue.

I don't know if any of this version stuff matters, but I'm OSX Sierra with a 1.8 JDK and 0.13.13 SBT. There is a Scala 2.12.1 on this machine.

$ sbt sbtVersion
[info] Loading project definition from /Users/robert.kuhar/dev/Hello/project
[info] Set current project to Hello (in build file:/Users/robert.kuhar/dev/Hello/)
[info] 0.13.13
$ java -version
java version "1.8.0_20"
Java(TM) SE Runtime Environment (build 1.8.0_20-b26)
Java HotSpot(TM) 64-Bit Server VM (build 25.20-b23, mixed mode)
$ scala -version
Scala code runner version 2.12.1 -- Copyright 2002-2016, LAMP/EPFL and Lightbend, Inc.

How do I get the "SBT Hello, World" to run on my dev box?

In which directory are you running sbt? you should go to the folder created by sbt new sbt/scala-seed.g8 and type: sbt run — nmat
@nmat that is where I am running it from; the directory Hello created by the template. — Bob Kuhar
Works on my machine ;) I have not idea where "Error exists in the bytecode" comes from, but I'm pretty sure it's something local to your environment. — lutzh

Brian Brian · Accepted Answer · 2017-03-10T00:51:56

Here's a way to do it without the sbt new plugin.

Create the following dirs and file in a directory Hello:

├── build.sbt
└── src
    └── main
        └── scala
            └── Hello.scala

Put this in Hello.scala

object Hello extends App{
  println("Hello")
}

In Hello/build.sbt add this line:

scalaVersion := "2.11.8

Run it with run

/tmp/Hello  $ sbt                                                                                                                                                                                                                                                                                                                                              [16:40:38]
[info] Loading global plugins from /home/brian/.sbt/0.13/plugins
[info] Set current project to hello (in build file:/tmp/Hello/)
> run
[info] Compiling 1 Scala source to /tmp/Hello/target/scala-2.11/classes...
[info] Running Hello 
Hello
...

I've had "mixed" results with the g8/giterate templates in the past but that may or may not be your issue. I've used https://github.com/sbt/sbt-fresh and that worked well. If your completely new to Scala and SBT the above code and build setup should get you started.

How do I get "sbt hello, world" to run?

1 Answers