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 package jason.stdlib;

Internal action: .literal.

Description: checks whether the argument is a literal, e.g.: "p", "p(1)", "p(1)[a,b]", "~p(1)[a,b]".


  • + argument (any term): the term to be checked.


  • .literal(b(10)): true.
  • .literal(b): true.
  • .literal(10): false.
  • .literal("Jason"): false.
  • .literal(X): false if X is free, true if X is bound to a literal.
  • .literal(a(X)): true.
  • .literal([a,b,c]): false.
  • .literal([a,b,c(X)]): false.

public class literal extends DefaultInternalAction {
    private static InternalAction singleton = null;
    public static InternalAction create() {
        if ( == null
             = new literal();
        return ;
    @Override public int getMinArgs() { return 1; }
    @Override public int getMaxArgs() { return 1; }
    public Object execute(TransitionSystem tsUnifier unTerm[] argsthrows Exception {
        return args[0].isLiteral();
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