Well, compilers have layers - you ain't outputting assembly from the AST layer directly, usually there is some kind of IR. Like LLVM have plenty of layers. And

Well, compilers have layers - you ain't outputting assembly from the AST layer directly, usually there is some kind of IR. Like LLVM have plenty of layers. And for a simple DSL you can usually just use a sufficiently expressive language, no need for macros. Like kotlin/Scala has html DSLs that look pretty decent. For anything more complex though, you can't just "compose stuff", a type system is a global property so for that you literally have to write something way more complex than a local macro should contain.