I'm not a lawyer but my understanding is that copying semantics could still be argued as creating a derivative work. This is what e.g. Whisper Systems claimed before publishing an axolotl spec, that anyone implementing the spec was doing so by deducing the semantic meaning of a copyleft piece of software and thus was a derivative work of said copyleft piece of software. This meant that the resulting binary was covered under the copyleft license (GPLv3 in that case, but my understanding of EPL is similar) https://medium.com/@wireapp/axolotl-and-proteus-788519b186a7
I don't know if Rich or the other Clojure copyright holders care enough to ever make trouble, but I'm pretty sure most companies with a decent legal team would think thrice before offering a piece of code built using Ferret
GCC has already solved the problem the other commenter you mention brings up with the runtime library exception https://www.gnu.org/licenses/gcc-exception-faq.html but I don't know if you can tack this on to the clojure-derived parts of ferret. I sure wish SFLC or someone was able to do legal counselling for new/small projects like this, I feel like a big reason people shy away from copyleft isn't the hippie dippie bullshit but because these interactions are impossible to reason about by laypersons
I don't know if Rich or the other Clojure copyright holders care enough to ever make trouble, but I'm pretty sure most companies with a decent legal team would think thrice before offering a piece of code built using Ferret
GCC has already solved the problem the other commenter you mention brings up with the runtime library exception https://www.gnu.org/licenses/gcc-exception-faq.html but I don't know if you can tack this on to the clojure-derived parts of ferret. I sure wish SFLC or someone was able to do legal counselling for new/small projects like this, I feel like a big reason people shy away from copyleft isn't the hippie dippie bullshit but because these interactions are impossible to reason about by laypersons