How to clear/reset a Scala REPL session (without having to kill the session)

A cool feature of the Scala REPL is that you can reset/clear a REPL session. To do so, just issue the :reset command, like this:

scala> :reset
Resetting interpreter state.
Forgetting this session history:

Assuming that you already have at least a little history in your REPL session, the :reset command will show you everything that it dumps, so the full output looks more like this:

scala> :reset
Resetting interpreter state.
Forgetting this session history:

trait Animal
class Person(name: String) extends Animal
class Employee(name: String) extends Person(name)
def printPerson(b: Boolean)(implicit p: Person) = if (b) println(p)
val p = new Person("person")
val e = new Employee("employee")

Forgetting all expression results and named terms: e, p, printPerson
Forgetting defined types: Animal, Employee, Person

In my case I was testing implicit values in parameter lists, and forgot to make the last two values implicit, so I decided to start my REPL session over again.

If you ever need to clear your Scala REPL session, it’s great that you can reset the session, rather than having to kill it and start over.

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