[derefr]

Even a "kitchen that fits in your pocket" isn't general enough. A library that parses a DSL, such that you can then code in that DSL, is still a lame duck if that library, plus the encodings of all the useful solutions in the domain, add up to more code than just the solutions would be when expressed in a general language. The ROI of (learning the DSL + maintaining the library) would be negative.

On the other hand, there are things like Prolog. You can think of Prolog as a backtracking constraint-solving library, and then another library that parses a DSL for expressing facts and procedural constraints and feeds it to the first library. But Prolog's language isn't really a DSL, because it isn't particular to any domain: there's no closed solution-space where Prolog applies. The efficiency gains you get from Prolog's elision of proceduralized contraint-solution code can apply to any program you write. And so its value is unbounded; its ROI is certainly positive, whatever the cost was to implement it.

That's the comparison that's useful here, I think. Is this something that only solves problems in one domain? Or is this something that could be applied to (at least some little bits of) any problem you encounter?