scala

Scala programming language interpreter and REPL

TLDR

Start REPL

$ scala

Run script

$ scala [script.scala]

Run with classpath

$ scala -cp [lib.jar] [script.scala]

Evaluate expression

$ scala -e "println(1 + 2)"

Run compiled class

$ scala [ClassName]

With specific JVM memory

$ scala -J-Xmx[2g] [script.scala]

Run in explain mode

$ scala -explain [script.scala]

SYNOPSIS

scala [-cp classpath] [-e expr] [options] [script] [args]

scala runs Scala programs and provides an interactive REPL. Scala combines object-oriented and functional programming on the JVM.The REPL evaluates expressions and shows results with types. Tab completion helps explore APIs. :help shows REPL commands.Scripts run directly without compilation. The Scala 3 runner can execute .scala files as scripts with dependencies.Classpath specifies libraries and compiled classes. Maven coordinates can specify dependencies in Scala 3.Compiler explanations help understand complex error messages. The explain mode provides detailed reasoning.The language supports type inference, pattern matching, implicits, and higher-order functions. It interoperates with Java seamlessly.

PARAMETERS

-cp, -classpath PATH

Set classpath for class files and libraries.

-e EXPR

Evaluate expression and print the result.

-J FLAG

Pass flag to JVM (e.g., -J-Xmx2g).

-deprecation

Show deprecation warnings.

-explain

Explain errors in detail with additional context.

-feature

Show feature warnings for advanced language features.

-help

Show help.

-version

Show version.

-X

Show advanced compiler options.

-Y

Show private compiler options.

CAVEATS

Scala 3 differs significantly from Scala 2. JVM startup adds latency. Memory usage can be high. Some features have learning curve.

HISTORY

Scala was designed by Martin Odersky at EPFL in Switzerland, with version 1.0 released in 2004. Scala 3 (Dotty), released in 2021, brought significant language improvements.