public static Mayhap <TResult> SelectMany <T, TMiddle, TResult>(
this Mayhap <T> @this,
Func <T, Mayhap <TMiddle> > selector,
Func <T, TMiddle, TResult> resultSelector)
{
Utilities.Guard.NotNull(selector, nameof(selector));
Utilities.Guard.NotNull(resultSelector, nameof(resultSelector));
return(@this.Bind(
x => selector(x).Select(
middle => resultSelector(x, middle))));
}
/// <summary>
/// (<**>)
/// <para>A variant of (<*>) with the arguments reversed.</para>
/// </summary>
public static Mayhap <TResult> Apply <TSource, TResult>(
this Mayhap <TSource> @this,
Mayhap <Func <TSource, TResult> > applicative)
{
// (<**>) :: Applicative f => f a -> f (a -> b) -> f b
// (<**>) = liftA2(\a f -> f a)
//
// A variant of '<*>' with the arguments reversed.
#if STRICT_HASKELL
return(Invoke(applicative, @this));
#else
return(applicative.Bind(f => @this.Select(f)));
#endif
}