[kaba0]

While I also believe several commenter’s opinion that libraries, frameworks can easily become DSLs themselves (e.g. isn’t Java streams basically a DSL for stream processes inside another language?), one really can’t talk about polyglottism without mentioning the ingenuity of GraalVM.

You basically write a dumb, easy parser and AST interpreter for your language, and it will magically turn into a JIT compiled dynamic language with state-of-the-art GCs and better performance than what you could likely come up with. And the best thing is that it really unifies the computing model where you can pass a python object to some js lib, effectively giving you every library ever written for any (implemented) language, which is the real productivity booster.

[adql]

Yes but library that turns a part of syntax of language into DSL to solve certain problem have advantage of developers already knowing that language, developers needing to learn only one language, and ability to use with that DSL anything else language libraries offer.

The problem is really "does the language app uses works for target audience that will be doing the DSL". If it does (Ruby makes pretty decent one), job done, if it doesn't, we end up in the mess of making toy languages (usually because developers want to do something fun and writing new small language can be pretty fun) or plugging something like Lua into it.