Pattern matching multiple related values required nested if statements or complex boolean logic. This was particularly cumbersome when the logic depended on combinations of multiple variables.

C# 8.0 introduces tuple patterns, allowing you to match against multiple values simultaneously in a single pattern. This is especially powerful with switch expressions for writing clear, concise logic based on combinations of values.

Code

Now

public string RockPaperScissors(string player1, string player2) => (player1, player2) switch
{
    ("rock", "scissors") => "Player 1 wins",
    ("scissors", "paper") => "Player 1 wins",
    ("paper", "rock") => "Player 1 wins",
    ("scissors", "rock") => "Player 2 wins",
    ("paper", "scissors") => "Player 2 wins",
    ("rock", "paper") => "Player 2 wins",
    _ => "Draw"
};

Before

public string RockPaperScissors(string player1, string player2)
{
    if ((player1 == "rock" && player2 == "scissors") ||
        (player1 == "scissors" && player2 == "paper") ||
        (player1 == "paper" && player2 == "rock"))
        return "Player 1 wins";
    if ((player1 == "scissors" && player2 == "rock") ||
        (player1 == "paper" && player2 == "scissors") ||
        (player1 == "rock" && player2 == "paper"))
        return "Player 2 wins";
    return "Draw";
}

Notes

• Create a tuple of values to match against: (value1, value2) switch { ... }
• Each arm matches against a tuple pattern: (pattern1, pattern2) => result
• Use _ as a discard pattern to match any value for that position
• Supports constant patterns, type patterns, and var patterns within tuple positions
• Particularly useful for state machines, game logic, or any multi-variable decision logic
• Order matters - the first matching pattern wins
• Type pattern improvements ^{C# 9.0} added relational patterns and or/and combinators that can be used within tuple positions

More information

• Specification
• Pattern matching overview