Scala
A JVM language combining object-oriented and functional programming — the language behind Apache Spark and a mainstay in data engineering.
Scala runs on the JVM and interoperates with Java libraries, while adding functional programming features like pattern matching, immutable data structures, and a powerful type system. It is most prominent as the language of Apache Spark (big data processing) and is used for backend services at companies like Twitter/X, LinkedIn, and Databricks. The Akka toolkit makes Scala a strong choice for reactive, concurrent systems.
Typical time to job-readiness: ~4 months.