mixedstrongtype

Mixedstrongtype is a concept in type system design describing a hybrid approach that combines mixed typing with strong typing guarantees. In this model, a type called MixedStrongType represents values that may originate from multiple concrete types (for example, numbers, strings, or composite values). At the same time, the system enforces safety by requiring explicit type guards, assertions, or static narrowing when a value is used in a context that requires a more specific type. The goal is to offer the flexibility of interchanging data across boundaries (such as between dynamically typed components and statically typed modules) while maintaining predictable error behavior.

In static contexts, variables of MixedStrongType can be assigned values of different base types. However, operations on such values are performed only after the value has been narrowed to a compatible type, either by runtime checks or by compile-time type predicates. If a mismatch is detected, a type error is raised.

This approach is related to gradual typing and soft typing. It can be realized via runtime type metadata and guards, or via static analysis that infers possible type sets and inserts guards automatically.

Common use cases include inter-language interop, API boundaries, and data deserialization, where inputs may be heterogeneous yet must be handled safely.

Limitations include potential performance overhead due to runtime checks, more complex error messages, and a larger burden on developers to provide and maintain appropriate guards.

See also: gradual typing, strong typing, dynamic typing, interop.