public void TestEIf()
{
var test1 = BF.EIf(false, () => "abc", () => 3);
Assert.AreEqual("abc", test1.Match(left: n => n.ToString(), right: BF.Identity));
var test2 = BF.EIf(false, () => test1, () => 19);
Assert.AreEqual("abc", test2.Match(left: n => n.ToString(), right: BF.Identity));
var test3 = BF.EIf(false, () => "abc", () => test1);
Assert.AreEqual("abc", test3.Match(left: n => n.ToString(), right: BF.Identity));
}
/// <summary>
/// Type-safe version of LINQs 'Single' and 'SingleOrDefault' function that returns a Maybe
/// instead of possibly throwing an exception or returning null
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="items">A queryable of elements that we want the only element of</param>
/// <returns>The only value in the queryable, or nothing if no such element exists or multiple elements exist</returns>
public static IMaybe <T> MaybeSingle <T>(this IQueryable <T> items)
{
return(items.MaybeSingle(BasicFunctions.Const <T, bool>(true).AsExpression()));
}
/// <summary>
/// Type-safe version of LINQs 'Single' and 'SingleOrDefault' function that returns a Maybe
/// instead of possibly throwing an exception or returning null
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="items">An enumerable of elements that we want the only element of</param>
/// <returns>The only value in the enumerable, or nothing if no such element exists or multiple elements exist</returns>
public static IMaybe <T> MaybeSingle <T>(this IEnumerable <T> items)
{
return(items.MaybeSingle(BasicFunctions.Const <T, bool>(true)));
}
