Predicates

Predicates are first-class Python objects that express conditions over a fact's fields. They compose with & | ~ and serialize cleanly.

Basic usage

from airules import Predicate

p = Light.color.eq("yellow") & Light.remaining_time.gt(5)

p.evaluate(Light(color="yellow", remaining_time=10))   # True
p(Light(color="yellow", remaining_time=2))             # False - same thing

# Compose with &, |, ~
either = Light.color.eq("red") | Light.color.eq("yellow")
not_green = ~Light.color.eq("green")

Available operators

Class	Method shorthand	Description
Eq	.eq(value)	Equality
Gt	.gt(value)	Greater than
Ge	.ge(value)	Greater than or equal
Lt	.lt(value)	Less than
Le	.le(value)	Less than or equal
Contains	.contains(value)	Substring or list membership
StartsWith	.startswith(prefix)	String prefix
EndsWith	.endswith(suffix)	String suffix
And	p & q	Boolean AND
Or	p | q	Boolean OR
Not	~p	Boolean NOT
Always	-	Always matches (used internally by @Default)

Case-insensitive matching

eq, startswith, endswith, and contains accept a keyword-only case_insensitive=True flag:

User.name.eq("alice", case_insensitive=True)          # matches "Alice", "ALICE"
User.name.startswith("dr.", case_insensitive=True)     # matches "Dr. Strange"
User.name.contains("smith", case_insensitive=True)     # matches "John SMITH"

Notes:

• eq ignores case only when both values are strings; numbers, None, and enums compare exactly.
• contains folds case for substring matches only - list/set membership stays exact.
• The flag survives to_dict() / from_dict() round-trips; it is omitted from the dict when False so older serialized predicates load unchanged.

Serialization

Predicates round-trip through plain dicts:

data = p.to_dict()
restored = Predicate.from_dict(data)

Store them in a database, diff them between deployments, or feed them into a rules-editor UI. See Introspection for dumping the full rule set.