[kccqzy]

Compile-time introspection and reflection have been implemented in GHC Haskell as the Generic class. Basically the compiler synthesizes a representation of your data type in terms of basic operations like :+: or :*: (for sum types and product types) and you can easily operate on them. Is that what you mean by compile-time introspection?

It's already being used (for many years in fact) to implement JSON serialization and deserialization in arson without depending on Template Haskell (kind of like macros).