- The article presents a type-safe generic data structure technique in C using unions and macros, avoiding void* and multiple #include approaches.
- A union with a 'payload' member enforces type safety at compile time, catching errors when adding wrong types to structures like linked lists.
- Flexible Array Members (FAM) solve memory and performance issues of void* by storing data within nodes, reducing allocations and cache misses.
- Macros like list_prepend automatically handle size and type enforcement using the ternary operator, with __typeof__() for return type casting.
- Using typedef with the List macro avoids compiler errors from structurally identical union types, though newer compilers may address this.