prolog passing a function as a variable, how to add arguments?
declarative, prolog
Solution
Specifically in SWI-Prolog you can use `call` . Quoting the manual:
call(:Goal, +ExtraArg1, ...)
Append ExtraArg1, ExtraArg2, ... to the argument list of Goal and call the result. For example, call(plus(1), 2, X) will call plus(1, 2, X), binding X to 3. The call/[2..] construct is handled by the compiler. The predicates call/[2-8] are defined as real (meta-)predicates and are available to inspection through current_predicate/1, predicate_property/2, etc. Higher arities are handled by the compiler and runtime system, but the predicates are not accessible for inspection.
where the plus indicates that the `argument must be fully instantiated to a term that satisfies the required argument type`, and the colon indicates that the `agument is a meta-argument` (this also implies "+").
Problem
I have this arbitrary function that I need to call many times with different variables. btw, this is SWI-Prolog ``` perform(V1,V2,V3,Function,Result):- % % do little stuf. % Function(Arg1,Arg2,Result). ``` This gives a syntax error. But passing a function as a variable without adding arguments works fine as in the following code: ``` perform(Function):- Function. sayHello:- write('hello'). :-perform(sayHello). ``` So how to add arguments to a variable function?