Uniform pattern for lambda input/output serialize

[hidden-dimensions]

Currently skygear lambda function takes either Object[] args or Map<String, Object> as input parameter, and returns JSONObject on LambdaResponseHandler, which make serialization asymmetric (toMap and fromJson).

Suggest to return Map<String,Object> on LambdaResponseHandler.

---

For kotlin we can expect a uniform serialization like the following:

data class TestData(
        val foo: String,
        val nested: Nested
) {
    data class Nested(
            val nestedInt: Int,
            val nestedString: String
    ) {
        fun toMap() = mapOf(
                "nestedInt" to nestedInt,
                "nestedString" to nestedString
        )
        companion object {
            @Throws(NullPointerException::class, ClassCastException::class)
            fun from(map: Map<*,*>): Nested {
                return Nested(
                        nestedInt = map["nestedInt"] as Int,
                        nestedString = map["nestedString"] as String
                )
            }
        }
    }

    fun toMap() = mapOf(
            "foo" to foo,
            "nested" to nested.toMap()
    )
    companion object {
        @Throws(NullPointerException::class, ClassCastException::class)
        fun from(map: Map<*, *>): TestData {
            return TestData(
                    foo = map["foo"] as String,
                    nested = Nested.from(map["nested"] as Map<*,*>)
            )
        }
    }
}

[carmenlau]

Since map is not the only result type for lambda, it would be string or array. So need further planning is needed. Will put this issue to backlog first and start planning again if it gets more votes.