Just another scratch pad¶
Notes on [Burstall1977]¶
Laws. Well expressed as known properties about the objects. Associativity, commutativity, etc..
i + j
— Does not commute on strings, but it does associate.A * M
— Commutes if A is a scalar and M a matrix, but does not commute if both are matrices. It associates for scalars and matrices alike being mixed.
In xotl.ql, this kind of information can be only provided by
isinstance()
inside a query expression, or by the object model (known only to the translator).