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.
