Adds mechanism for converting Fleece schemas to Aeson Values #49
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This allows for the use of Fleece schemas in defining `ToJSON` instances, like we do using `toParser` for `FromJSON` instances. Originally the plan was to replace the existing `Encoder` using `Encoding` and `Series` with one that uses `Value` and adding the `toEncoding` step in `encode` and `encodeStrict`. This results in a different JSON encoding, however - insertion order for key/value pairs is not preserved when using `Value`. This resulted in test failures because while the same fields are present, they may appear in a different order, so the encoded bytestrings won't always match.
| -- the same and will be decoded the same as `toJSON (toValue a)`, it will not | ||
| -- be exactly the same bytestring produced by the two. | ||
| -- | ||
| data ToValue a |
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Should I make the same change for other similar types? (Encoder, Decoder, etc)
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I think we likely should, but I don't want to make a bunch of extra work for this PR.
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I don't actually think we can make this a newtype since it's taking two arguments - the name and the Value-producing function.
| {-# LANGUAGE TypeOperators #-} | ||
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| module Fleece.Aeson.ToValue | ||
| ( ToValue (..) |
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Do we need to export the construction here at all, or is it always going to be built by the FC.Fleece instance? If it's the later, I'd say we just export the type. For the former, export a constructor function instead.
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I don't think we have to, but I did it here to be consistent with other modules (Encoder, Decoder, etc) where we export the constructor. Should we only export the type in those cases, too?
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I would think so, but again, I think that change could easily be done after this.
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One reason many of these constructors are exported is to ensure that end users who want to add new primitives to the schema language via their own classes can create instances of their type classes for the core Fleece instance types
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We're currently using the data constructor for Encoder in Schmods: Service.Wingspan uses it to make an encoder for Beeline that emits invalid JSON and should never actually get invoked.
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Also using the data constructor in Data.Accessorial to use Aeson's type class instances ToJSON inside an Fleece Encoder
This allows for the use of Fleece schemas in defining
ToJSONinstances, like we do usingtoParserforFromJSONinstances.Originally the plan was to replace the existing
EncoderusingEncodingandSerieswith one that usesValueand adding thetoEncodingstep inencodeandencodeStrict. This results in a different JSON encoding, however - insertion order for key/value pairs is not preserved when usingValue. This resulted in test failures because while the same fields are present, they may appear in a different order, so the encoded bytestrings won't always match.