Threading macros, core.async in Clojure that does quite a bit of code rewriting, anaphoric macros, with- macros that bind to some context, destructing in Clojure, slingshot's try+/catch+ in Clojure.
None of that is strictly impossible in languages without macros but best case you'd have to wrap everything in a copious amount of lambdas making for very nasty looking code. Worst case some compile time optimizations wouldn't be possible.
Any single macro isn't THE killer macro, but giving all of them up is a big deal. Similarly replicating semantics of a single macro in some other language may be doable but getting many of them to compose would be tough.
Most popular languages tend to get new keywords, operators and other forms of syntax over time implicitly acknowledging limitations of the "user space" syntax. You don't see that as much in LISPs since most such things can be implemented as a macro.
None of that is strictly impossible in languages without macros but best case you'd have to wrap everything in a copious amount of lambdas making for very nasty looking code. Worst case some compile time optimizations wouldn't be possible.
Any single macro isn't THE killer macro, but giving all of them up is a big deal. Similarly replicating semantics of a single macro in some other language may be doable but getting many of them to compose would be tough.
Most popular languages tend to get new keywords, operators and other forms of syntax over time implicitly acknowledging limitations of the "user space" syntax. You don't see that as much in LISPs since most such things can be implemented as a macro.