This question from 2013 asks whether m.se is appropriate forum to discuss languages similar to WL.
One mentioned, mathics, doesn't seem to be around anymnore, or at least page is unresponsive.
I have a slightly different question. Is m.se appropriate to solicit user opinions for what features one might like to see in a de-novo symbolic open source language.
I'm specifically interested in a language that maximizes compatibility with WL but perhaps is based on a subset of the features.
A potential example of using a subset might include eg using
Association structures to define option patterns or to organize in a common format the sometimes arbitrary format of arguments - think of various Graphics functions? (Kernighan once said associative arrays are a very powerful foundation of other structures)
The motivation for an open-source version should be obvious but basically in the 21st century, proprietary languages are fading. As a data scientist who's worked in large organizations and startups in healthcare and fintech, to get a proprietary platform in the door is a very hard sell. This is why Mathematica is mostly used by single-person consultancies.