GoKawiilCopper language creator trims union types down to option-type-only experiment
The developer behind the Copper programming language describes scaling back an earlier attempt at full union types (lists of alternative types a value can hold) to a simpler, option-type-only design. The post details restrictions imposed for efficient compilation, including banning nested unions and treating type order as significant to simplify value representation and enable syntactic sugar for common error-handling patterns.
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The trade-offs described illustrate a recurring tension in language design between expressive type systems and compiler simplicity or performance, particularly for low-level languages aiming to interoperate with existing C libraries. Restricting unions to ordered, non-nested pairs could make the feature easier to implement and faster at runtime, but may limit flexibility for more complex type-safety use cases that fuller union types support in other languages.
- Copper's creator is narrowing a prior union-type experiment to focus on simpler option types.
- Design restrictions include disallowing nested unions and making type order within a union meaningful.
- The ordered-union approach lets the language offer error-handling syntactic sugar without building an Error type into the language itself.
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Published there as: “Union Types and Option Types”
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