You can think of it as clang, but controlled by a lua engine instead of the CLI. It's not just macros, you have control over generation of build artifacts. By default you're running in JIT mode, but you can at any time bundle up some procedures and spit out an object file or link them into an executable.
You can also call back into Lua from the native code, and use it to generate more native code. You get back some of the cool self-modifying executable techniques of the days gone by, without having to completely YOLO it.
Well Rust procedural macros can run arbitrary code, so that's not such a big difference. I'd say the larger one is having access to actual AST data structures available if you want them. Rust forces you to parse the token stream yourself and serialize it again. Also, Terra allows user defined keywords so it's a lot easier to create nice looking DSLs (which is my personal use case).
You can think of it as clang, but controlled by a lua engine instead of the CLI. It's not just macros, you have control over generation of build artifacts. By default you're running in JIT mode, but you can at any time bundle up some procedures and spit out an object file or link them into an executable.
You can also call back into Lua from the native code, and use it to generate more native code. You get back some of the cool self-modifying executable techniques of the days gone by, without having to completely YOLO it.
Well Rust procedural macros can run arbitrary code, so that's not such a big difference. I'd say the larger one is having access to actual AST data structures available if you want them. Rust forces you to parse the token stream yourself and serialize it again. Also, Terra allows user defined keywords so it's a lot easier to create nice looking DSLs (which is my personal use case).