Absence of side effects is a necessary, but not sufficient, condition for referential transparency. Referential transparency means that an expression (such as a function call) can be replaced with its value. This requires that the expression is pure, that is to say the expression must be deterministic (always give the same value for the same input) and side-effect free.
absence of side effects is a necessary but not sufficient condition for referential transparency referential transparency means that an expression (such as a function call) can be replaced with its value this requires that the expression is pure that is to say the expression must be deterministic (always give the same value for the same input) and side-effect free