public static IEnumerable <T> ToEnumerable <T>(this Enumerate <T> source)
{
var e = source();
IMaybe <T> value;
while (!((value = e()) is None <T>))
{
yield return(value.Value);
}
}
public static List <T> ToList <T>(this Enumerate <T> source)
{
var list = new List <T>();
var e = source();
IMaybe <T> value;
while (!((value = e()) is None <T>))
{
list.Add(value.Value);
}
return(list);
}
public static Enumerate <TResult> SelectMany <T, TResult>(this Enumerate <T> source, Func <T, Enumerate <TResult> > selector)
{
return(() =>
{
var e = source();
IMaybe <T> lastOuter = new None <T>();
IMaybe <TResult> lastInner = new None <TResult>();
Enumeration <TResult> innerSet = null;
return () =>
{
do
{
while (lastInner is None <TResult> )
{
lastOuter = e();
if (!lastOuter.HasValue)
{
return lastOuter.TransposeEmpty <TResult>();
}
innerSet = selector(lastOuter.Value)();
lastInner = innerSet();
if (lastInner is Some <TResult> )
{
return lastInner;
}
}
lastInner = innerSet();
}while (lastInner is None <TResult>);
return lastInner;
};
});
}
public static Enumerate <T> Where <T>(this Enumerate <T> source, Func <T, bool> filter)
{
return(source.SelectMany(t => filter(t) ? Return(t) : Empty <T>()));
}
public static Enumerate <TResult> Select <T, TResult>(this Enumerate <T> source, Func <T, TResult> selector)
{
return(source.SelectMany(a => Return(selector(a))));
}