Is this using Lightning? We've done SPARC and x86 in pure Ruby without libraries here (for other reasons). You might be surprised how easy this stuff is to do. I assumed he just emits instructions.

I don't know why he wastes time with an actual parseable assembly language. Ruby and Python are vastly better languages than Assembler. They have all the same textual features that Assembler has, plus a real programming language to do things like virtualized registers.

I looked at Lightning recently, but it looked sort of as if it was dead. Is it still being maintained?