/// <summary>
/// Map the sequence using the function provided
/// </summary>
/// <typeparam name="B"></typeparam>
/// <param name="f">Mapping function</param>
/// <returns>Mapped sequence</returns>
public Seq <B> Map <B>(Func <A, B> f)
{
IEnumerable <B> Yield()
{
foreach (var item in this)
{
yield return(f(item));
}
}
return(SeqEnumerable <B> .New(Yield()));
}
/// <summary>
/// Filter the items in the sequence
/// </summary>
/// <param name="f">Predicate to apply to the items</param>
/// <returns>Filtered sequence</returns>
public Seq <A> Filter(Func <A, bool> f)
{
IEnumerable <A> Yield()
{
foreach (var item in this)
{
if (f(item))
{
yield return(item);
}
}
}
return(SeqEnumerable <A> .New(Yield()));
}
/// <summary>
/// Monadic bind (flatmap) of the sequence
/// </summary>
/// <typeparam name="B">Bound return value type</typeparam>
/// <param name="bind">Bind function</param>
/// <returns>Flatmapped sequence</returns>
public Seq <C> SelectMany <B, C>(Func <A, Seq <B> > bind, Func <A, B, C> project)
{
IEnumerable <C> Yield()
{
foreach (var a in this)
{
foreach (var b in bind(a))
{
yield return(project(a, b));
}
}
}
return(SeqEnumerable <C> .New(Yield()));
}
/// <summary>
/// Monadic bind (flatmap) of the sequence
/// </summary>
/// <typeparam name="B">Bound return value type</typeparam>
/// <param name="f">Bind function</param>
/// <returns>Flatmapped sequence</returns>
public Seq <B> Bind <B>(Func <A, Seq <B> > f)
{
IEnumerable <B> Yield()
{
foreach (var a in this)
{
foreach (var b in f(a))
{
yield return(b);
}
}
}
return(SeqEnumerable <B> .New(Yield()));
}
/// <summary>
/// Append operator
/// </summary>
public static Seq <A> operator +(Seq <A> x, Seq <A> y)
{
IEnumerable <A> Yield(Seq <A> sx, Seq <A> sy)
{
foreach (var a in sx)
{
yield return(a);
}
foreach (var b in sy)
{
yield return(b);
}
}
return(SeqEnumerable <A> .New(Yield(x, y)));
}
public static Seq <A> Cons <A>(this A head, IEnumerable <A> tail) => SeqEnumerable <A> .New(head, tail);
public static Seq <A> createRange <A>(IEnumerable <A> items) => SeqEnumerable <A> .New(items);