Of course. "Maybe" is clearly of a different character than "Int", but both are types.
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Indeed, they are both types, just like 42 and True are both values. But they are different "kinds" of type * -> * and * resp. You can get a static "compile time" kind error, which is like a type error "one level up" so to speak. i.e. the type annotations themselves are incoherent
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One of the things my students of Haskell consistently have trouble with is understanding why a declaration like "instance Monoid Either where..." isn't allowed.
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Maybe the mental model error is related to the inelegance that the kind system is not polymorphic. e.g. you can 'map' a unary or binary function, so why not Monoid Either?
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Would be neat to be able to curry kinds. 🤔
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Yeah the special rules around type level programming in haskell is annoying. I think the dependent haskell stuff aims to make it a bit less janky? I dunno though.
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I do like that they are moving to `Type` instead of `*` for the type of types - would have made this stuff easier to learn at first! My brain always got really confused seeing stuff like `* -> *`.
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funnily enough it makes sense to me; * as a type wildcard
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Would you call `Int` an 'integer wildcard'? I guess to me it seemed like some weird scary thing, and I assumed I couldn't use my existing knowledge about how types worked in order to understand it.
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now that you mention it, Int may as well be an integer wildcard
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I guess I more take issue with the special casing. If wildcard were a more common way to look at types, then that would makes sense? Like how `[a]` is confusing notation for the type constructor of lists, when `List a` would have sufficed? I dunno 😅