// functors and a list

class Procedure
{
    fun void run()
    {
        // empty
    }
}

class UnaryProcedure
{
    fun void run(Object arg)
    {
        // empty
    }
}

class UnaryPredicate
{
    fun int test(Object arg)
    {
        return false;
    }
}

class UnaryFunction
{
    Object @ default;

    fun Object evaluate(Object arg)
    {
        return default;
    }
}

class Comparator
{
    fun int compare(Object arg0, Object arg1)
    {
        return 0;
    }
}

class List
{
    // TODO: static initial capacity
    Object @ values[];

    fun int cap()
    {
        return values.cap();
    }

    fun int size()
    {
        // TODO:  count non-null refs
        return values.cap();
    }
    
    fun void resize(int capacity)
    {
        // TODO:  copy existing values
        Object @ ignore[capacity] @=> values;
    }
    
    fun Object get(int index)
    {
        return values[index];
    }

    fun void set(int index, Object value)
    {
        value @=> values[index];
    }

    fun void assign(Object value)
    {
        for (0 => int i; i < cap(); i++)
        {
            value @=> values[i];
        }        
    }
    
    fun void transform(UnaryFunction fn)
    {
        for (0 => int i; i < cap(); i++)
        {
            fn.evaluate(values[i]) @=> values[i];
        }
    }
    
    fun void forEach(UnaryProcedure procedure)
    {
        for (0 => int i; i < cap(); i++)
        {
            procedure.run(values[i]);
        }
    }

    fun void forEach(UnaryPredicate predicate, UnaryProcedure procedure)
    {
        for (0 => int i; i < cap(); i++)
        {
            if (predicate.test(values[i]))
            {
                procedure.run(values[i]);
            }
        }
    }
    
    // TODO:
    // fun List copy();
    // fun List subList(int from, int to);
    // fun void sort(Comparator comparator);
}

class TestUnaryProcedure extends UnaryProcedure
{
    fun void run(Object arg)
    {
        <<< "test", arg >>>;
    }
}

TestUnaryProcedure testProcedure;

List list;
Object a;
Object b;
4 => list.resize;
[ a, b ] @=> list.values;
<<< "cap =", list.cap(), "size =", list.size() >>>;
list.forEach(testProcedure);

1::second => now;