Scala REPL FAQ: How do I add a Jar file to the Scala REPL classpath? (The Scala REPL is the interactive command line you get if you just type
scala at your command line.)
To add a new jar file to the Scala REPL classpath (interactive command line classpath), use the
:require command at the command line, like this:
scala> :require myjar.jar
After you do this, you should see a reply from the REPL like this:
Added '/Users/Al/tests/myjar.jar'. Your new classpath is: ".:/Users/Al/tests/myjar.jar"
At this time you can begin using the classes in your jar (though you'll have to import them, as usual).
Adding a jar file to the classpath when you start the Scala interpreter
I usually find that I need to add a jar file to the Scala REPL after I've been running the REPL, but if you happen to know that you're going to need to add a jar file to the classpath when you start the interpreter, you can do so like this:
$ scala -cp junit-4.8.1.jar
As you can see, this approach uses the usual "-cp" classpath option that is used by the scalac and javac commands.
Scala REPL help
I learned about the Scala REPL
:require command by looking at the help from within the REPL. Here's what that help looks like with my current version of Scala, version 2.12.1:
scala> :help All commands can be abbreviated, e.g., :he instead of :help. :edit <id>|<line> edit history :help [command] print this summary or command-specific help :history [num] show the history (optional num is commands to show) :h? <string> search the history :imports [name name ...] show import history, identifying sources of names :implicits [-v] show the implicits in scope :javap <path|class> disassemble a file or class name :line <id>|<line> place line(s) at the end of history :load <path> interpret lines in a file :paste [-raw] [path] enter paste mode or paste a file :power enable power user mode :quit exit the interpreter :replay [options] reset the repl and replay all previous commands :require <path> add a jar to the classpath :reset [options] reset the repl to its initial state, forgetting all session entries :save <path> save replayable session to a file :sh <command line> run a shell command (result is implicitly => List[String]) :settings <options> update compiler options, if possible; see reset :silent disable/enable automatic printing of results :type [-v] <expr> display the type of an expression without evaluating it :kind [-v] <expr> display the kind of expression's type :warnings show the suppressed warnings from the most recent line which had any