All great industrial apps are DSLs for specific domains, because often time end users are much smarter & craftier than developers. Some great examples: - AutoCad (vector drawing DSL on top of Lisp) - Mathematica (symbolic algebra DSL - Lisp & C) - Aspen One (Thermodynamics/Chemistry DSL on FORTRAN) - COMSOL (Multiphysics DSL C++) - Verilog (FPGA design DSL C) and also general purpose tools like Regex, XLA, CERN/Root, SQL, HTML/CSS,...