We propose to introduce a macro system into Swift. At a very high level, macros can be explicitly triggered with syntax such as #stringify(x + y), subsuming a number of existing expressions that use similar syntax already (#line, #colorLiteral(...), etc.) with a general features. Macros can also be triggered more implicitly in response to type checking, e.g., applying a macro to the argument passed to a function. Macro arguments are type-checked so that tooling behaves similarly to today, but macro evaluation involves transforming the syntax so that it can serve a number of different use cases.