CADiZ

Reference manual / Non-standard extensions to Z / Schema overriding


The schema overriding operator composes two operations so that the result behaves like its right operand schema does when that is applicable, and like the left operand otherwise.

Expression = Expression , \zovr , Expression;

The LATEX mark-up of \zovr is \zovr. The troff mark-up of \zovr is zov.

Schema overriding could be defined as follows, using the notation of type-constrained generics.

_ \zovr _ [\dagger X, Y] == \lambda S : \power X; T : \power Y @ (S \land \lnot pre T) \lor T

IT 4-Jan-2002