Author here. Development is indeed on hold for now. However, Crystal core team has plans to build a DSL into Crystal to allow for creating Ruby native extension

Author here. Development is indeed on hold for now. However, Crystal core team has plans to build a DSL into Crystal to allow for creating Ruby native extensions. There are some technical limitations with how I handled defining functions, which has also become obsolete with recent changes to Crystal. However, there is another approach (macro based) demonstrated at https://github.com/spalladino/crystal-ruby_exts https://github.com/spalladino/crystal-ruby_exts. The macro approach is what is needed. At time of first development, this was just an experiment and I didn't feel like redo-ing it this way. Now that core team has plans for similar functionality, I'd rather not finish a half baked solution that distracts from what theirs will likely be.