Comparisons and Membership

Comparisons and Membership#

EQL supports all standard Python comparison operators and adds powerful membership checks for querying containers and lists.

Standard Comparisons#

You can use the following operators directly on symbolic attributes:

  • Equality: == and !=

  • Ordering: <, <=, >, >=

# Select robots with high battery
query = entity(r).where(r.battery >= 80)

Hint

EQL automatically handles type coercion where appropriate, making your queries more resilient to minor data differences.

Membership Checks#

EQL provides two main ways to check for membership in collections: in_() and contains().

1. The in_() Operator#

Use in_() to check if a value exists within a specific collection.

from krrood.entity_query_language.factories import in_

# Select robots whose names are in a specific list
allowed_names = ["R2D2", "BB8"]
query = entity(r).where(in_(r.name, allowed_names))

2. The contains() Operator#

Use contains() to check if a symbolic attribute (which is a collection) contains a specific value.

from krrood.entity_query_language.factories import contains

# Select robots that have 'laser' in their equipment list
query = entity(r).where(contains(r.equipment, "laser"))

Warning

Python’s native in operator (e.g., value in container) cannot be overridden to return a symbolic expression. You must use EQL’s in_() or contains() functions for these checks inside a query.

Full Example: Filtering by Categories and Capabilities#

Let’s build a query that uses both standard comparisons and membership checks.

from dataclasses import dataclass
from typing import List
from krrood.entity_query_language.factories import variable, entity, an, Symbol, in_, contains

@dataclass
class ExampleRobot(Symbol):
    name: str
    battery: int
    tags: List[str]

robots = [
    ExampleRobot("R2D2", 100, ["astromech", "repair"]),
    ExampleRobot("C3PO", 20, ["protocol", "translator"]),
    ExampleRobot("K2SO", 80, ["security", "combat"])
]

r = variable(ExampleRobot, domain=robots)

# We want robots that:
# 1. Have at least 50% battery
# 2. Are in either the "security" or "protocol" category (using in_)
# 3. Have the "combat" tag (using contains)
query = an(entity(r).where(
    r.battery >= 50,
    contains(r.tags, "combat")
))

for robot in query.evaluate():
    print(f"Match: {robot.name} (Tags: {robot.tags})")

Match: K2SO (Tags: ['security', 'combat'])

API Reference#