json.prelude

A typical module that talks to JSON in Mojo touches the same handful of names: loads / dumps / load / dump for the Python- like entry points, Value / Null for the result type, ParserConfig / SerializerConfig for the rare-tuning knob, and the reflection serde shortcuts serialize_json / deserialize_json / try_deserialize_json. json.prelude is the wildcard-importable shortcut for that exact set, so the canonical import block shrinks from 5-6 lines to one::

from json.prelude import *

@fieldwise_init
struct Person(Defaultable, Movable):
    var name: String
    var age:  Int

    def __init__(out self):
        self.name = ""
        self.age = 0

def main() raises:
    var p = deserialize_json[Person]('{"name":"Alice","age":30}')
    print(p.name, p.age)
    print(dumps(serialize_value(p), indent="  "))

Domain-specific surfaces are deliberately not re-exported so the prelude stays small enough that the import block of a real module still documents which features it actually uses:

• JSONPath (jsonpath_query, jsonpath_one) -- import from json.jsonpath.
• JSON Patch / Merge Patch (apply_patch, merge_patch, create_merge_patch) -- import from json.patch.
• JSON Schema (validate, is_valid, ValidationResult, ValidationError) -- import from json.schema.
• Streaming / lazy (LazyValue, StreamingParser, ArrayStreamingParser) -- import from json.lazy / json.streaming.
• Manual serde traits (Serializable, Deserializable, to_json_value, to_json_string, get_int / get_string / get_bool / get_float) -- import from json.serialize and json.deserialize.
• simdjson FFI (SimdjsonFFI) -- import from json.cpu.simdjson_ffi.

For those, import the specific names from the matching module. The prelude is the "first ten lines of code" surface, not the kitchen sink.