Untyped Typescript or Error Prone Covariance

Some time ago I wrote this short article about co- and controvariance in Kotlin and how these features help the developer to write less error prone code. When I talked with some colleagues about TypeScript, I recognized that, despite some experiences I made with small pet projects, I do no know about type variance in TypeScript. Thus, I decided to take a look and was surprised. TypeScript is not that well-typed as I thought…

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