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kotlinlang

<https://medium.com/@Robert_Chrzanow/kotlins-missing-type-either-51602db80fda>

<@U43TWHVK8> In case you have not already run into it, we have Either, EitherT, monadic comprehensions for all monads and other similar FP datatypes and abstraction in Kategory. <https://github.com/kategory/kategory/blob/master/kategory/src/main/kotlin/kategory/data/Either.kt>
There is other instances of Either in other libs too, Funktionale also has an Either <https://github.com/MarioAriasC/funKTionale/blob/master/funktionale-either/src/main/kotlin/org/funktionale/either/Disjunction.kt>

Good article explaining the absolute basics, but I don't really get why you're talking about "product" and "sum" types: why is that information useful in practice?

Thanks! I'm aware of these libraries. I'm writing my own library of functional abstractions to better grok them.

I wanted to quickly cover how algebraic data types construct new types before showing a generic instance of a sum type.