Scala, C, Javascript. Scala covers mainstream OO-programming and Haskell-style modern functional programming (monads, higher-kinded types). Moreover via Akka y

Scala, C, Javascript. Scala covers mainstream OO-programming and Haskell-style modern functional programming (monads, higher-kinded types). Moreover via Akka you have access to Erlang-style distributed programming. C is vital for low-level programming like operating sytems and network stacks. C might be replaced eventually by Rust but if that happens at all, it will take at a decade or so. Javascript is without competition for anything in the browser. All three languages have vast library and tool ecosystems at their disposal.