Hands-on Scala Programming

Scala exercises based on Li Haoyi's "Hands-on Scala Programming" book.

Running through Ammonite

Ammonite can run simple Scala script files, which is any file containing Scala code, ending in .scala.

Basic Script Run

Run script once:

 amm  script.scala

Watching Scripts

If you are working on single script, you can use amm --watch or amm -w to watch the script and re-run it when things change.

amm -w script.scala

Exit by pressing Ctrl-C.

Scripts loading to REPL

You can open up a REPL with access to the functions in Scala script by using --predef flag.

 amm --predef  script.scala

Given script.scala has helloWorld method defined, then it could be accessed in REPL.

// script.scala
def helloWorld(name: String) = {
   s"Hello World, $name"
}
...
$> amm --predef script.scala
@> helloWorld("Jonny")
@> res0: String = "Hello World, Jonny"

Load to REPL and Watch

If you need to edit large script file in the editor, but still want to test it in REPL, you may combine --watch and --predef flags, as follows:

amm -w --predef script.scala

If you make changes to the script file, you need to exit the REPL using Ctrl-D and -w flag will make sure to restart the REPL upon change.