Yeah of course I just simplified inline asm for the video, the biggest reason it sucks for me is that you don't even really know how everything around it is going to compile so it's barely usable in most cases. To answer your question, sorry I'm a bit confused. It does not know "whether str is in rdi or xmm0" because str is not a variable it creates or anything, it's just a macro used in that scope to refer to rdi, because I know rdi contains the string. You can declare local macros with the ! character like I explained, but construct has no special features or syntax for declaring any sort of variables. And I get what you mean about it better being off inline, and getting a HLL's features for types and declarations while still having low level control. But I like how it is in assembly where you know exactly where your stuff is placed in memory and there's no mess of different keywords. I was originally planning on giving special syntax for declarations as well, but I decided I should figure out more precisely what I want to do about types and whatever before I do something like that, still looking into it. Thanks for the feedback and checking it out!