Crate dataflow_rs_derive 

The proc-macro behind #[derive(FunctionConfig)]: a derive must live in a proc-macro crate of its own, and one derive serves the built-ins and hosts alike.

The generated code names nothing but ::dataflow_rs::function::__private, ::core and ::std, so the library must be reachable as ::dataflow_rs. A dependent keeps the dependency key dataflow-rs, and renames v3, not v4, when both are in scope. Inside the crate, extern crate self as dataflow_rs does it.

Derive Macros

FunctionConfig

Derives FunctionConfig for a function’s typed configuration, and ConfigField, so a derived config nests inside another.