> For that I would need to see actual, regular controlled experiments from PL researchers showing that a given language or construct yields measurable dividends

> For that I would need to see actual, regular controlled experiments from PL researchers showing that a given language or construct yields measurable dividends over another, such as reductions in deficits, program size, or development time. There's certainly a lack of empirical user research in the field, when the research has that aim. However, the point of many research languages/features is not that it reduces development cost, etc. but that it exists at all. The article gives examples of non-PL research, eg. the discovery of an incremental algorithm to calculate convex hulls, and these are legitimate results on their own; regardless of whether they "lower convex hull discovery costs", etc. The PL angle is the discovery of general abstractions, eg. a language for incremental computation, of which convex hull discovery is just one of many programs. The discovery of such an abstrction is also a legitimate result on its own; regardless of whether it "lowers incremental algorithm discovery costs"; etc. These results are a "pure" basis for language and library implementors to work from. If that incremental computation language only existed as, say, a collection of Java classes, then it would be difficult for other implementors (eg. in Javascript) to know which parts of the architecture are fundamental to the approach and which are artefacts of using Java. Of course, when investigating which primitives to use, there may be no existing language capable of expressing them (short of embedding an interpreter; in which case, you've just created a new language anyway!). Few academic language creators expect their languages to be adopted. They're usually proofs of concept, or meant to inform and inspire future work. Only a few are meant to be used for real work (for one thing, it places a maintenance burden on the researcher!).