isSame

isSame is a term used in programming and data processing to describe a predicate that tests whether two values correspond to the same entity under a defined notion of sameness. The exact semantics of sameness can vary by language and context, and so isSame is often implemented to reflect either identity (whether two references point to the same object) or value equality (whether two values are equivalent in content).

Two broad interpretations are common. Referential identity treats isSame as a test of whether two references refer to the exact same object in memory. Value equality, by contrast, checks whether two distinct objects have equal content according to a chosen equality rule. Some libraries and languages expose explicit operators for one or the other, while others rely on a function-like predicate named isSame.

In practice, isSame appears in different forms. In Python, for example, the identity check is performed with the is operator, while equality uses ==; a function named isSame would typically implement identity checks. In JavaScript, Object.is(a, b) tests sameness with a behavior that differs slightly from the strict equality operator === in edge cases. In data modeling and databases, a concept similar to isSame might compare primary keys or unique identifiers to determine whether two records refer to the same entity.

Semantics should be clearly documented because the meaning of sameness affects correctness, such as memoization, deduplication, and data integrity checks. Common related concepts include equality, identity, and reference equality.