/// <summary>
/// Map to a new type.
/// </summary>
/// <typeparam name="TLeft">The type of the left.</typeparam>
/// <typeparam name="TLeftResult">The type of the left result.</typeparam>
/// <typeparam name="TRight">The type of the right.</typeparam>
/// <typeparam name="TRightResult">The type of the right result.</typeparam>
/// <param name="source">The source.</param>
/// <param name="selectLeft">The select left.</param>
/// <param name="selectRight">The select right.</param>
/// <returns></returns>
public static Either <TLeftResult, TRightResult> Map <TLeft, TLeftResult, TRight, TRightResult>(
this IEither <TLeft, TRight> source,
Func <TLeft, TLeftResult> selectLeft,
Func <TRight, TRightResult> selectRight)
{
return(source.Match(
onLeft: leftValue => new Either <TLeftResult, TRightResult>(selectLeft(leftValue)),
onRight: rightValue => new Either <TLeftResult, TRightResult>(selectRight(rightValue))));
}
/// <summary>
/// Performs an given Action based on whether the IEither(TLeft, TRight) contains a Left or
/// Right value.
/// </summary>
/// <typeparam name="TLeft">The type of a potential Left value.</typeparam>
/// <typeparam name="TRight">The type of a potential Right value.</typeparam>
/// <param name="either">An IEither(TLeft, TRight) instance.</param>
/// <param name="leftAction">Action used for a Left value.</param>
/// <param name="rightAction">Action used for a Right value.</param>
public static void Match <TLeft, TRight>(
this IEither <TLeft, TRight> either, Action <TLeft> leftAction, Action <TRight> rightAction)
{
either.Match <object>(
left =>
{
leftAction(left);
return(null); // We're not using the result of the match, so just return null.
},
right =>
{
rightAction(right);
return(null);
});
}
public EitherEnumerable <TLeft, TResult> Bind <TResult>(Func <TRight, EitherEnumerable <TLeft, TResult> > f)
{
return(new EitherEnumerable <TLeft, TResult>(Out.Match(
right: xs => xs.Select(x => f(x).Out).Sequence().Select(ys => ys.SelectMany(BasicFunctions.Identity)),
left: l => l.AsLeft <TLeft, IEnumerable <TResult> >())));
}
public static IMaybe <TRight> ToMaybe <TLeft, TRight>(this IEither <TLeft, TRight> m) => m.Match(_ => (IMaybe <TRight>) new Nothing <TRight>(), r => new Just <TRight>(r));
/// <summary>
/// Applies the <paramref name="selector" /> to the right side and flattens.
/// </summary>
/// <param name="this">The <see cref="IEither{TL,TR}" /> to select on.</param>
/// <param name="selector">The function to apply to the right side of the <see cref="IEither{TL,TR}" />.</param>
/// <typeparam name="TL">The left type of the <see cref="Either{TL,TR}" />.</typeparam>
/// <typeparam name="TR">The right type of the <see cref="Either{TL,TR}" />.</typeparam>
/// <typeparam name="TOut">The output type of the <paramref name="selector" />.</typeparam>
/// <returns>An <see cref="IEither{TL,TR}" />.</returns>
public static IEither <TL, TOut> SelectMany <TL, TR, TOut>(this IEither <TL, TR> @this, Func <TR, IEither <TL, TOut> > selector)
=> @this.Match(x => OfLeft <TL, TOut>(x), selector);