Sure they can. You can use server side languages like Clojure, Erlang, Elixir, F# and a few others I'm sure I'm missing. There also exist libraries for some la

Sure they can. You can use server side languages like Clojure, Erlang, Elixir, F# and a few others I'm sure I'm missing. There also exist libraries for some languages that introduce immutable data structures, like pysistance for Python.