In Idris, why do interface parameters have to be type or data constructors?

In the Idris programming language, why do interface parameters have to be type or data constructors, and what is the rationale behind this design choice?

In Idris, interface parameters have to be type or data constructors because interfaces are designed to work with types that have specific structures and behaviors. This design choice ensures that the methods defined in an interface can be implemented consistently across different types, leveraging their constructors to provide meaningful implementations.

Rationale Behind This Design Choice Type Safety: By restricting interface parameters to type or data constructors, Idris ensures that only valid types can implement the interface, enhancing type safety and reducing the risk of runtime errors.

Consistency: This restriction helps maintain consistency in how methods are implemented across different types, making it easier to reason about the code and ensuring that implementations adhere to the expected structure.

Overloading: Interfaces in Idris are similar to type classes in Haskell or traits in Rust. By using type or data constructors, interfaces can provide overloading of functions, allowing the same function name to be used with different types while ensuring that each type provides a specific implementation.

By requiring interface parameters to be type or data constructors, Idris ensures that implementations are consistent and type-safe, making it easier to work with polymorphic functions and maintain clean, readable code.