There's a lot of niche languages for niche specialties. Like Ada/Spark for aviation/defense/safety-critical systems, Coq and Isabelle for formal verification, F

There's a lot of niche languages for niche specialties. Like Ada/Spark for aviation/defense/safety-critical systems, Coq and Isabelle for formal verification, FORTRAN and Julia for scientific computing, Mathematica for pure/applied math, Prolog for logic programming/planning/expert systems, R for stats, MiniZinc and TLA+ for modeling, Racket for compiler work, etc. Ideas in these fields come through clearer/more cleanly in these languages. Learning the language is easy, the field is harder, but ideas of the field are reflected in the language.