ExhaustiveMatching.Analyzer 0.5.0

ExhaustiveMatching.Analyzer

ExhaustiveMatching.Analyzer adds exhaustive matching to C# switch statements and expressions.

Get compiler errors for missing cases in a switch statement or expression. Mark which switches should have exhaustiveness checking by throwing an exception in the default case. Exhaustiveness checking works not just for enums, but for classes and interfaces. Turn them into discriminated unions (aka sum types) by marking them with the Closed attribute and listing the cases. ExhaustiveMatching.Analyzer goes beyond what other languages support by handling full inheritance hierarchies.

Full documentation on the GitHub Project.

Quickstart Guide

Mark a switch statement or expression as exhaustive and get errors for missing cases.

using ExhaustiveMatching;

public enum CoinFlip { Heads, Tails }

// ERROR Enum value not handled by switch: Tails
switch (coinFlip)
{
    default:
        throw ExhaustiveMatch.Failed(coinFlip);
    case CoinFlip.Heads:
        Console.WriteLine("Heads!");
        break;
}

// ERROR Enum value not handled by switch: Tails
_ = coinFlip switch
{
    CoinFlip.Heads => "Heads!",
    _ => throw ExhaustiveMatch.Failed(coinFlip),
};

Create discriminated unions (aka sum types) and get errors for missing switch cases.

[Closed(typeof(IPv4Address), typeof(IPv6Address))]
public abstract class IPAddress { … }

public class IPv4Address : IPAddress { … }
public class IPv6Address : IPAddress { … }

// ERROR Subtype not handled by switch: IPv6Address
switch (ipAddress)
{
    default:
        throw ExhaustiveMatch.Failed(ipAddress);
    case IPv4Address ipv4Address:
        return ipv4Address.MapToIPv6();
}