var match = new Matcher<string>
{
    {s => s.Length == 1, s => Console.WriteLine("1")},
    {s => s.Length == 2, s => Console.WriteLine("2")},
    {s => true, s => Console.WriteLine("Many")}
}.ToAction();

match("a") // 1
match("aa") // 2
match("aaa") // Many

var match = new Matcher<string, int>
{
    {s => string.IsNullOrEmpty(s), (string _) => 0},
    {s => true, s => s.Length}
}.ToFunc();

int len1 = match(null); // 0
int len2 = match("abc"); // 3

var match = new Matcher<Option<int>, int?>
{
    // Predicate matching requires explicit type annotation
    {i => i is None, (Option<int> _) => null},
    {i => i as Some<int>, i => i.Value},
}.ToFunc();

match(new None<int>()); // null
match(new Some<int>(10)); // 10

var match = new UnionMatcher<Union<string, StringBuilder>, string>
{
    {UnionCase._<string>(), s => s},
    {UnionCase._<StringBuilder>(), sb => sb.ToString()}
}.ToFunc();

match("string"); // string
match(new StringBuilder("stringBuilder")); // stringBuider

var match = new Matcher<string, string>
{
    {Case.Rx(new Regex("\\d{2}")), s => s},
    {Case.Rx(new Regex("test\\s(\\d{3})")), s => s}
}.ToFunc();

match("12"); // 12
match("test 123"); // 123