
HANDBOOK
/ GENTLE PRIMER
/ Control Structures
/
The Conditional Statement
A frequent case is that, if a certain condition holds, a specific action
should be initiated, otherwise nothing should happen.
This could be expressed by an alternative statement
with an empty second alternative.
For example,
(| IsBad(Item) Complain(Item) || /*nothing*/ |)
This can be abbreviated by a conditional statement.
[| IsBad(Item) Complain(Item) |]
An alternative statement has the form
The members Mi are elaborated in the given order.
If one member fails elaboration is completed and
and the conditional statement succeeds.
If all members succeed the conditional statement succeeds.
A conditional statement cannot define variables
because if one member fails its conceptual empty second case is taken
which defines no variables.
