transcendental-lisp/src/function/builtin/cons/CAR.java

package function.builtin.cons;

import function.*;
import sexpression.*;

public class CAR extends LispFunction {

    private ArgumentValidator argumentValidator;

    public CAR() {
        this.argumentValidator = new ArgumentValidator("CAR");
        this.argumentValidator.setExactNumberOfArguments(1);
        this.argumentValidator.setEveryArgumentExpectedType(Cons.class);
    }

    public SExpression call(Cons argumentList) {
        argumentValidator.validate(argumentList);
        Cons argument = (Cons) argumentList.getCar();

        return argument.getCar();
    }

}