Add functionality to construct products in applicative / monadic way #101
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joroKr21
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Sep 15, 2022
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joroKr21
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- TODO: Add tests
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| value <- fieldMap.get(field).toRight(s"Missing field '$field';") | ||
| parsed <- parser.parse(value, accum) | ||
| yield parsed | ||
| if accum then inst.constructA(parseField)(pure, map, ap) |
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I got so confused as to why constructA and constructM would be different for Either and then realized you're doing naughty things with ap 😂
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Yeah, I didn't want to spend too much time defining Validated so I just used an inconsistent Either
| final def erasedConstructA[F[_]](f: Any => F[Any])(pure: Pure[F], map: MapF[F], ap: Ap[F]): F[Any] = | ||
| traverseProduct(new ArrayProduct(is), (tc, _) => f(tc))(pure, map, ap) | ||
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| final def erasedConstructM[F[_]](f: Any => F[Any])(pure: Pure[F], map: MapF[F], tailRecM: TailRecM[F]): F[Any] = |
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Is this just a stacksafe version of constructA or is there some other difference that I've missed?
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constructA is based on Applicative:
- It can be parallel
- It cannot short circuit (evaluates for all fields)
- It is not stack safe (currently) - but it could be optimized if we build a tree instead of a list of
ap
constructM is based on Monad:
- It is always sequential
- It can short circuit
- It is stack safe
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cats.Applicative actually has map2Eval which can short circuit but that's too much complexity for Shapeless
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@TimWSpence here is a failed attempt to make traverse and constructA stack safe: #103
But it doesn't actually build a tree ...
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Sorry, just saw this. Will have a look!
