[9q9]

   Terra paper

I didn't mean to push Terra in particular, and I agree that doing meta-programming is easier in the same language you do normal programming in. I just mentioned the Terra paper since it provided a rationale for using meta-programming in high-performance programming (I could have pointed to others making the same argument).

Rust's procedural macros are standard compile-time meta programming.

   proc macros do AST->AST folds)

Last time I looked (I have not used Rust for a while) procedural macros operate over tokens, not ASTs. Maybe that changed?

[steveklabnik]

It hasn’t changed; we didn’t want to freeze the AST forever, so we went with the token approach. There are libraries to form an AST though.