This is just a toy Haskell library to encode large JSON objects in streaming fashion. It provides a ToJSONStream class that can be anyclass derived for types which have a Generic instance. As in the example below:

data VeryLargeObj m = VeryLargeObj {
    field1 :: Stream (Of Text) m (),
    field2 :: Stream (Of Text) m ()
    }
    deriving stock Generic
    deriving anyclass (ToJSONStream m)

This library also provides a UseToJSONInstance newtype wrapper for those with existing bespoke ToJSON instances for their types. So if you have a ToJSON instance for a type and you want to derive a ToJSONStream instance for it without duplicating the code, you can just:

deriving via (UseToJSONInstance MyType) instance (Monad m => ToJSONStream m MyType)

Naturally, this will use the ToJSON instance underneath so it won't stream your type incrementally when serializing.

How streaming is it?

• Objects' fields are each streamed separately (and recursively, and reasonably lazily)
• Arrays' elements are each streamed separately (and recursively, and reasonably lazily)
• Text and String are streamed whole, not incrementally.
• Bool and numeric types are streamed whole, not incrementally.