There aren&#x27;t many popular non-Turing-complete languages because most language designers are stuck in a cycle of redesigning Algol and Lisp for the umpteenth time. Very few new mainstream languages have anything new to say that applies to anything outside writing simple algorithms or gluing libraries together. Scala, Ruby, D, Rust, CoffeeScript, Clojure... I could go on. They&#x27;re all just rehashes of the same ingredients. Why this is the trend I&#x27;m not sure, but I bet it&#x27;s related to the fact that these same languages try to position themselves as complete ecosystems, rather than simple tools which form but part of an engineering solution.<p>There&#x27;s been some promising movement recently in the direction of DSLs. Reactive programming seems to finally be gaining popularity, which allows us to replace gobs of glue code with simple declarations. Erlang&#x27;s OTP has been gaining popularity too, allowing declarative design in the large.