The `loadModule_` primitive now returns a fiber when a module is loaded, and the C runtime handles calling it via `PRIM_RUN_FIBER` instead of the Wren code manually invoking the result. This removes the conditional `if (result != null) result.call` from the `import_` method in both the builtin source and the embedded libSource string, and adds `IS_FIBER` macro to `wren_value.h` for type checking in the native implementation.
The Wren scripts in this directory get converted to C string literals and then inserted into their respective .c files so that the interpreter can load them directly without having to do any file IO.
The script that does this copying is script/generate_builtins.py.
You can invoke using make builtin.