Prior art: Lisp reader macros

[js-choi]

There’s a list of similar syntaxes from three other programming languages. It might also be worth including the reader macros from the Lisps, e.g., Common Lisp reader macros. These might be less similar to this proposal than C#/Swift/Rust attributes, but they’re still perhaps related. They extends the source-code parser (the “reader”) itself using a table of prefix operators. And the Clojure dispatch reader macro reserves a single prefix character # as a larger space in advance for future use.

[littledan]

Interesting parallel!