look into proto-lens-jsonpb

[martyall]

It's possible that this library could allow is to get away with less manual json definitions or WrappedVals

https://hackage.haskell.org/package/proto-lens-jsonpb

[IvantheTricourne]

https://github.com/tclem/proto-lens-jsonpb/blob/master/src/Data/ProtoLens/JSONPB/Class.hs#L224-L226

This function might help out with types with String Fields issues as described in #92.

[IvantheTricourne]

https://github.com/tclem/proto-lens-jsonpb/blob/master/src/Data/ProtoLens/JSONPB/Class.hs#L159-L162

This one should address the other 2 categories

[IvantheTricourne]

I should be able to give a pretty thorough pros/cons write up for this.

See my WIP branch

[IvantheTricourne]

Given below, I don't think we benefit using this library. Aside from not having to worry about possible null values (i.e., because every PB instance is required to declare a default field value), we actually incur writing more boilerplate and manual JSON instances.

CONS

• we cannot use generic deriving
• we must manually derive FromJSONPB instances via (.:) for any nullable type
• we cannot completely remove wrapped values: certain request types (i.e., Query) actually use string parameters (i.e., height); JSON-PB only allows for string to int parsing.

PROS

• every nullable field must have a protolens FieldDefault instance (i.e., we don't have to handle Nulls)
• every FromJSON instance just uses (.:) and not (.?)/(.!=)
• most ToJSON and FromJSON instances can be derived from the corresponding PB equivalent

[IvantheTricourne]

In a similar effort of trying to use generic JSON parsers, I've come to another conclusion:

We should only use this library if we find any value in encoding defaults inside of a FieldDefault versus directly in an Aeson parser:

newtype Foo = Foo {..}

instance FromJSON Foo where
  parseJSON = withObject "Foo" $ \v -> Foo
    <$> v .:? "some_nullable_field" .!= someDefault

versus with PB:

newtype Foo = Foo {..}

instance FromJSONPB NullableField where
  parseJSONPB = ...
instance FieldDefault NullableField where
  fieldDefault = someDefault

instance FromJSON Foo where
  parseJSON = withObject "Foo" $ \v -> Foo
    <$> v .: "some_nullable_field"