Revises the "union" method in SchemaVisitor ... #302
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…e optimised dispatched logic * Creates a `Alt.Dispatcher` construct that aims at streamlining the implementation of the `union` methods in SchemaVisitors, which is the hardest due to the fact that the implementor has to think about memoization. * Creates an `EncoderK` typeclass (used by Alt.Dispatcher) to generalise over what is an encoder, and streamline further the implementation of union encoders. * Extract a generalisation of SchemaVisitor, named SchemaCompiler, which could be used to unify Schematic, which @kubukoz really really wants. * Examplifies the use of `Alt.Dispatcher` in DocumentEncoderSchemaVisitor
| def absorb[A](f: A => Document): DocumentEncoder[A] = | ||
| new DocumentEncoder[A] { | ||
| def apply: A => Document = f | ||
| override def canBeKey: Boolean = false |
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this is cheating a little but we're planning on removing that canBeKey stuff in a subsequent PR
| import smithy.api.Http | ||
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| object SchemaVisitorPathEncoder extends SchemaVisitor[MaybePathEncode] { self => |
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This is a bit over my head, but I like it. We can eventually rewrite most of our implementation and get a free improvement with it |
There's not that many that actually encode things in this repo, and it might be a little bit less efficient than the raw management that the jsoniter interpreter does. |
| trait Precompiler[F[_], G[_]] { self => | ||
| def apply[A](label: String, instance: F[A]): G[A] | ||
| def toPolyFunction[U]: PolyFunction[Alt[F, U, *], G] = | ||
| new PolyFunction[Alt[F, U, *], G] { | ||
| def apply[A](fa: Alt[F, U, A]): G[A] = self.apply(fa.label, fa.instance) | ||
| } | ||
| } |
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suggestion: some helper for converting from F ~> G (e.g. if you want to simply lift a visitor to Precompiler) would be great (it'd just ignore the label)
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tbh I don't actually have a need for this, so feel free to ignore
| * | ||
| * Useful in particular when encoding unions | ||
| */ | ||
| trait EncoderK[F[_], Result] extends Contravariant[F] { |
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Would this be useful?
implicit def encoderKForFunction[B]: EncoderK[* => B, B] =
new EncoderK[* => B, B] {
def apply[A](fa: A => B, a: A): B = fa(a)
def absorb[A](f: A => B): A => B = f
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Mmm, possibly, doesn't hurt to add.
... to make it easier to write memoised dispatching logic
The
unionmethod in SchemaVisitor is an obvious footgun, because it makes it a hard to memoise the compilation of schemas for each alternative.This PR revises the
unionmethod to expose a new constructAlt.Dispatcher, which does the heavylifting of memoizing the result of compiling schemas, and dispatching the union instance to the correct alternative.Alt.Dispatcherconstruct that aims at streamlining theimplementation of the
unionmethods in SchemaVisitors, which is thehardest due to the fact that the implementor has to think about memoization.
EncoderKtypeclass (used by Alt.Dispatcher) to generaliseover what is an encoder, and streamline further the implementation of
union encoders.
be used to unify Schematic, which @kubukoz really really wants.
Alt.Dispatcherin DocumentEncoderSchemaVisitorThis should remove the need for #260