Prolog

higher order programming

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meta-call predicates

meta-call predicates are used to call terms constructed at run time

call/1

call/1 is used to call a term

call(person(N, doe) = person(john, L)).
% N = john, L = doe.

call/[2..]

call/[2..] appends arguments to the predicate’s argument list and calls the result

plus(X, Y, R) :- X + Y #= R.

call(plus(X), 3, 7). % effectively calls `plus(X, 3, 7)`
% X = 4.

append/2

append/2 appends a list of arguments to the argument list and calls the result

append(plus(X), [3, 7]).
% X = 4.

• used when the number of arguments isn’t fixed

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