This module provides instances of ToJSON and FromJSON for MonoidMap.

These instances provide objects of type MonoidMap k v with a JSON encoding that is identical to objects of type Map k v, which are serialised as either JSON objects or arrays depending on the key type k.

Encoding as JSON objects

>>> encode $ MonoidMap.fromList [("abc", Sum 1), ("def", Sum 2)]

"{\"abc\":1,\"def\":2}"

Encoding as JSON arrays

>>> encode $ MonoidMap.fromList [((1,2), Sum 3), ((2,3), Sum 5)]

"[[[1,2],3],[[2,3],5]]"

Encoding to JSON

The ToJSON instance satisfies the following laws:

toEncoding == toEncoding . MonoidMap.toMap
toJSON     == toJSON     . MonoidMap.toMap

Decoding from JSON

The FromJSON instance satisfies the following law:

parseJSON == fmap (fmap MonoidMap.fromMap) parseJSON

Mappings from keys to values that decode to mempty are not included in decoded MonoidMap objects.