Notational Conventions

Every procedure is available via field selection from its module. Some procedures are so common that there is an abbreviation. For example, the procedure NoNumber.label is available as Label. Every procedure description in this document starts with an application scheme. For example

{Label +RT ?L}

• If the first letter of the designator procname is written in lower case, the prodedure is available as module . procname where module denotes the name of the module given in the top margin. For example, the procedure List.subB is documented on page under the line {subB ·..}. If the first letter of the designator procname is written in upper case, it is available by the abbreviation procname ; and in addition as module . procname' where procname' results from procname by downcasing the first letter and deleting the string module . For example, the procedure IsNumberB is available as Number.isB.
• Procedures with suffix B denote a boolean function or a procedure taking boolean functions as argument. For constraint programming, every boolean function has a counterpart without the suffix B that succeeds when the boolean function returns True and fails when the boolean function returns False. For example, the unary boolean function (binary procedure) Number.isB, also available as IsNumberB, has a corresponding succeeding or failing unary procedure Number.is, also available as IsNumber. Every procedure taking boolean functions as argument has a counterpart without suffix B that expects as arguments succeeding or failing procedures instead of boolean functions. For example, the binary function (ternary procedure) List.filterB, also available as FilterB, takes as second argument a boolean function and thus can be called like in Ys={List.filterB Xs IsNumberB}. There is a corresponding binary function List.filter, also available as Filter that takes as second argument a succeeding or failing procedure and thus can be called like in Ys={List.filter Xs IsNumber}.
• Associated with every argument of a procedure is a type. The type of an argument is indicated by the name of the argument, using the following abbreviations:

  

  We use indices as in R1 to disambiguate several occurrences of arguments of the same type. We combine these abbreviations as in RT meaning ``record or tuple''. We use the suffix s to indicate lists of a certain type (e.g. Is stands for a list of integers). Additionally, we allow ourselves to prefix these arguments as in PortI indicating an integer that is used as a port.

• We distinguish between input (+) and output arguments (?). The application fails, if any of the argument types of input arguments is violated. Implementations should provide for a way to report such a violation at compile or run time. If no input argument type is violated, the application suspends until all input arguments are bound to a value of their type. Suspension of the application does not depend on the constraints on output arguments.