public static DataType Cons(T x, DataType ts)
{
if (IsEmpty(ts))
{
return(new One(x, RList <Tuple <T, T> > .Empty));
}
if (ts is Zero zero)
{
return(new One(x, zero.RList));
}
if (ts is One one)
{
return(new Zero(RList <Tuple <T, T> > .Cons(new Tuple <T, T>(x, one.Alpha), one.RList)));
}
throw new ArgumentException("must be null, Zero or One", nameof(ts));
}
public static DataType Fupdate(Del f, int i, DataType ts)
{
if (ts is One one)
{
if (i == 0)
{
return(new One(f(one.Alpha), one.RList));
}
return(Cons(one.Alpha, Fupdate(f, i - 1, new Zero(one.RList))));
}
if (ts is Zero zero)
{
RList <Tuple <T, T> > .Del fp0 = value => new Tuple <T, T>(f(value.Item1), value.Item2);
RList <Tuple <T, T> > .Del fp1 = value => new Tuple <T, T>(value.Item1, f(value.Item2));
var fp = i % 2 == 0 ? fp0 : fp1;
return(new Zero(RList <Tuple <T, T> > .Fupdate(fp, i / 2, zero.RList)));
}
throw new ArgumentException("must be Zero or One", nameof(ts));
}
private static Tuple <T, DataType> Uncons(DataType dataType)
{
if (dataType is One one)
{
if (RList <Tuple <T, T> > .IsEmpty(one.RList))
{
return(new Tuple <T, DataType>(one.Alpha, Empty));
}
return(new Tuple <T, DataType>(one.Alpha, new Zero(one.RList)));
}
if (dataType is Zero zero)
{
var xy = RList <Tuple <T, T> > .Head(zero.RList);
var psp = RList <Tuple <T, T> > .Tail(zero.RList);
return(new Tuple <T, DataType>(xy.Item1, new One(xy.Item2, psp)));
}
throw new ArgumentException("must be Zero or One", nameof(dataType));
}
public static T Lookup(int i, DataType ts)
{
if (ts is One one)
{
if (i == 0)
{
return(one.Alpha);
}
return(Lookup(i - 1, new Zero(one.RList)));
}
if (ts is Zero zero)
{
var node = RList <Tuple <T, T> > .Lookup(i / 2, zero.RList);
if (i % 2 == 0)
{
return(node.Item1);
}
return(node.Item2);
}
throw new ArgumentException("must be Zero or One", nameof(ts));
}
public One(T alpha, RList <Tuple <T, T> > .Node list)
: base(list)
{
Alpha = alpha;
}
public Zero(RList <Tuple <T, T> > .Node list)
: base(list)
{
}
protected DataType(RList <Tuple <T, T> > .Node list)
{
RList = list;
}
