[NTG-context] Commands with arguments before in ConTeXt

I've read the following is not possible in TeX \def#1\macro{blabla#1} where arguments come before. The only partial exceptions are commands like \atop or \over, which are in fact primitives. Is there a way to do this in ConTeXt? Could it be a feature request for LuaMetaTeX? I've seen Hans experimenting a lot with new primitives and new possibilities for arguments, like #0 and co., so I ask in case it's not too nonsensical to propose it. Regards Jairo :)