/// <summary>
/// Returns the minimum and maximum value of an iterable by comparing the results of a
/// selector function. In case of multiple occurrences the first instance is returned.
/// </summary>
/// <typeparam name="TItem">
/// The type of the values in the <paramref name="source"/>.
/// </typeparam>
/// <typeparam name="TKey">
/// The type of the values returned by the <paramref name="keyFunc"/> function.
/// </typeparam>
/// <param name="source">
/// The enumerable of values from which to get the minimum and maximum.
/// </param>
/// <param name="keyFunc">
/// The selector function that converts the values in the <paramref name="source"/> to the
/// values that are compared.
/// </param>
/// <param name="comparer">
/// The comparer for the values returned by the selector.
/// </param>
/// <returns>
/// A value tuple containing the minimum (first element) and maximum (second element).
/// </returns>
/// <exception cref="ArgumentNullException">
/// If the <paramref name="source"/> or <paramref name="keyFunc"/> or
/// <paramref name="comparer"/> is null.
/// </exception>
/// <exception cref="InvalidOperationException">
/// If the <paramref name="source"/> contains no elements.
/// </exception>
public static MinMaxResult <TItem> MinMaxBy <TItem, TKey>(
this IEnumerable <TItem> source,
Func <TItem, TKey> keyFunc,
IComparer <TKey> comparer
)
=> MinMaxOps.MinMaxBy(source, keyFunc, comparer);
/// <summary>
/// Returns the minimum and maximum value of an iterable by comparing the results of a
/// selector function. In case of multiple occurrences the first instance is returned.
/// </summary>
/// <typeparam name="TItem">
/// The type of the values in the <paramref name="source"/>.
/// </typeparam>
/// <typeparam name="TKey">
/// The type of the values returned by the <paramref name="keyFunc"/> function.
/// </typeparam>
/// <param name="source">
/// The enumerable of values from which to get the minimum and maximum.
/// </param>
/// <param name="keyFunc">
/// The selector function that converts the values in the <paramref name="source"/> to the
/// values that are compared.
/// </param>
/// <returns>
/// A value tuple containing the minimum (first element) and maximum (second element).
/// </returns>
/// <exception cref="ArgumentNullException">
/// If the <paramref name="source"/> or <paramref name="keyFunc"/> is null.
/// </exception>
/// <exception cref="InvalidOperationException">
/// If the <paramref name="source"/> contains no elements.
/// </exception>
public static MinMaxResult <TItem> MinMaxBy <TItem, TKey>(
this IEnumerable <TItem> source,
Func <TItem, TKey> keyFunc
) where TKey : IComparable <TKey>
=> MinMaxOps.MinMaxBy(source, keyFunc);
