Variadic Generics ideas that won't work for Rust

10 months ago

Variadic generics in Rust would allow implementing traits for tuples with an arbitrary number of fields.
Three common but flawed proposals for variadic generics are discussed: using iterators, variadic recursion, and first-class types.
Using iterators fails because there's no guarantee tuple members implement the required trait, and mapping tuples is clunky.
Variadic recursion, inspired by C++, splits logic across multiple trait implementations, leading to poor developer experience and compiler challenges.
First-class types, inspired by Zig, would require massive changes to Rust's type system and introduce post-monomorphization errors.
The article concludes that variadic generics need a syntax for trait bounds on all tuple members and iteration over them with type safety.
The Rust lang team and community members endorse the need for proper variadic generics over the discussed alternatives.

Hasty Briefsbeta