VDM-10 Language Manual

VDM-10 Language Manual
Examples: Using the map GroupG defined in the preceding example, we have:
mk (2,1,0) in set rng GroupG
mk ("Romania",2,1,0) not in set rng GroupG
mk (,2,1,0) mk ("Romania",2,1,0)
6.11 Record Expressions
Syntax: expression = . . .
| record constructor
| record modifier
| . . . ;
record constructor = ‘mk ’, name, ‘(’, [ expression list ], ‘)’ ;
≡ true
≡ true
≡ true
record modifier = ‘mu’, ‘(’, expression, ‘,’, record modification,
{ ‘,’, record modification } ‘)’ ;
record modification = identifier, ‘|->’, expression ;
Semantics: The record constructor has the form:
✞
mk_T(e1, e2, ..., en)
✡✝
✆
where the type of the expressions (e1, e2, ..., en) matches the type of the corresponding
entrances in the composite type T.
The record modification has the form:
✞
✡✝
mu (e, id1 |-> e1, id2 |-> e2, ..., idn |-> en)
where the evaluation of the expression e returns the record value to be modified. All the
identifiers idi must be distinct named entrances in the record type of e.
✆
Examples: If sc is the value mk Score(,3,0,0,9) then
✞
✡✝
mu (sc, drawn |-> sc.drawn + 1, points |-> sc.points + 1)
≡ mk_Score(,3,1,0,10)
✆
Further examples are demonstrated in the function win. This function takes two teams and
a set of scores. From the set of scores it locates the scores corresponding to the given teams
(wsc and lsc for the winning and losing team respectively), then updates these using the
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