guard

programming 1. In functional programming, a Boolean

expression attached to a function definition specifying when

(for what arguments) that definition is appropriate.

2. In (parallel) logic programming, a Boolean expression

which is used to select a clause from several alternative

matching clauses.

See Guarded Horn Clauses.

3. In parallel languages, a Boolean expression which

specifies when an message may be sent or received.

(1995-05-09)