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Kotlin's rich errors: Native, typed errors without exceptions


At KotlinConf 2025, the Kotlin team showcased progress toward Rich Errors with union types. After years of watching languages slowly adopt patterns that Elm has championed since day one, it’s exciting to see Kotlin taking this significant step toward more explicit, type-safe error handling. And in a very “native” Kotlin way at that! I vividly remember this announcement giving my functional heart a pleasant jolt, but I haven’t found the time for a write-up until now. Better late than never, though:

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