I once wrote a rudimentary x86 assembler in about 250 lines of Clojure:

https://github.com/nathell/lithium/blob/master/src/lithium/a...

In general, I find that s-expressions are actually a nice syntax for assembly languages. For x86, they kind of sidestep the AT&T vs. Intel conundrum, and you get to write macro-like functions in the host Lisp that compile down to s-expressions.