Rust: “Explain GATs Like I'm 5 Years Old”

Re:Rust: “Explain GATs Like I'm 5 Years Old” by orblivion on Monday November 07, 2022 @10:32AM (#33507080)

I forget what exactly a GADT is (even though I've used Haskell a bit before). But just going by the linked example from Reddit, you could make a generic `map` function that worked on any container type. You'd have to implement the map function separately for each type. But then you could make a bunch of utility functions that you'd implement once that use the generic `map` under the hood, and all of those container types would be able to use those utility functions.

Not a Rust guy but I think that's the idea.

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Re:Rust: “Explain GATs Like I'm 5 Years Old” by kibwen on Monday November 07, 2022 @10:45AM (#33507292)

Just so that we're clear on acronyms for everyone out there, "GADT" is a computer science term for "generalized algebraic data type", which has no relation to "GAT", which is just Rust terminology for generics in associated types (even in Rust, I doubt that anyone will bother to refer to "GAT" in the coming years, rather than just lumping them in with the concept of associated types in general; there's really no need to teach them separately).

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Re:Rust: “Explain GATs Like I'm 5 Years Old” by ghostwriter on Monday November 07, 2022 @06:11PM (#33513852)

> you could make a generic `map` function that worked on any container type.

not only container types, it can be any type that has a consistent context of evaluation for the final value being calculated: "doing async IO", "doing optional presence", "doing potentially erroneous extraction", and so on. In that sense, "doing multiplicity of values" is the context expressing a container type you mentioned as an example.

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