/// <summary>
/// Combines <c>Io</c>'s but constructing new <c>IO</c>s
/// that eval and append the results of the original <c>IO</c>s.
/// </summary>
public static Monoid <Io <A> > Io <A>(Monoid <A> monoid) => Of(
() => IoMonad.Of(() => monoid.Default),
(x, y) => IoMonad.Of(() => monoid.Concat(x.Eval(), y.Eval())));
/// <summary> /// Combines <c>Some</c>s, ignoring <c>None</c>s. /// </summary> public static Monoid <Maybe <A> > Maybe <A>(Monoid <A> monoid) => Of(None <A>, (x, y) => x.AndOr(y, monoid.Concat));