sweetjs was a good idea, but I've found it hard to use, or rather..it's not the using part that's hard, but writing your own macro.

sweetjs has this hygienic thing that renames identifiers. To prevent it from renaming, there are many hoops that you have to jump through to prevent it.

sweetjs introduces of a lot of new concepts. These concepts are not as easy to understand as the ones in C. The macros are certainly more powerful. It's just that assuming it's C-like macro will give you the wrong kind of expectation with sweetjs.