Contents - Cultural View

Quark Framework 261
//illustrates positionally based case expression extraction of the
//"name" field of the RegularEmployee data constructor
RegularEmployee empname _ _ -> empname;
;
b) By field name in a case expression:
/**
* @arg employee
* @return the employee's name
*/
employeeName :: Employee -> String;
employeeName employee =
case employee of
//illustrates field-name based case expression extraction of the
//"name" field of the RegularEmployee data constructor
RegularEmployee {name} -> name;
;
This method is obviously more stable with respect to changes in data constructor arguments than the positional
version
c) By a selector expression
/**
* @arg employee
* @return the employee's name
*/
employeeName :: Employee -> String;
employeeName employee =
//illustrates data constructor field selection of the directReports
//field
employee.RegularEmployee.name;
Note that CAL allows multiple constructor arguments to be cited in a case extractor, along with multiple constructors
to match on (so long as they all have the named arguments). So, the following scenario is possible (assuming the
data declaration includes the employeeID field and new constructors for Contractor and Associate):
// ...snip...
case employee of
//illustrates multiple field case expression extraction over multiple
//data constructors. Note the local renaming of the employeeID field
//to 'id'
(RegularEmployee | Contractor | Associate) {name, employeeID = id } -> (name, id);
;
// ...snip...