broadcast:listen/2

Availability::- use_module(library(broadcast)).(can be autoloaded)

listen(+Template, :Goal)

Register a listen channel. Whenever a term unifying Template is broadcasted, call Goal. The following example traps all broadcasted messages as a variable unifies to any message. It is commonly used to debug usage of the library.

?- listen(Term, (writeln(Term),fail)).
?- broadcast(hello(world)).
hello(world)
true.