rust-like proc_macro is very important,

[huiseliming]

New language should implement features that C++ lacks,
Can use macros to visit ast for code generation or replace very useful

[lexi-nadia]

Hi! See 3b674c4, which addresses this topic. In short: macros are very powerful but very complex, and if possible, we'd like to have a simpler model for metaprogramming in Carbon.