Example: Using indexing in symbolic expressions

This example demonstrates capturing indexing (the getitem operator) on symbolic variables. You can index into containers held by your symbolic variable, and the operation will be represented symbolically in the query.

from dataclasses import dataclass
from typing_extensions import List, Dict
from entity_query_language import an, entity, let, symbolic_mode, symbol

@symbol
@dataclass
class Body:
    name: str
    props: Dict[str, int]

@dataclass
class World:
    bodies: List[Body]

world = World([
    Body("Body1", {"score": 1}),
    Body("Body2", {"score": 2}),
])

with symbolic_mode():
    b = let(type_=Body, domain=world.bodies)
    # use indexing on a dict field
    query = an(entity(b, b.props["score"] == 2))

results = list(query.evaluate())
assert len(results) == 1 and results[0].name == "Body2"