17. Match | Talos

A match statement considers a value and compares against several possible matching patterns. After which and appropriate block of code can be executed if matched successfully.

In the simplest form, a match statement compares against values of the same type.

match ("a") {
    "a": Debug.println("First latin character");
    "z": Debug.println("Last latin character");
    *: Debug.println("Some other character");
}

Unlike other languages, cases do not fall-through to one-another. Each case expects a following statement. To instead match more than one case for a code-block, we can combine the cases.

match ("a") {
    "a", "A": Debug.println("Found letter 'a'");
    *: Debug.println("Was not the letter 'a'");
}

Or for more specific matching, we can use a function guard.

// Prepare a guard for our values
let guard = fn (ch: String) => ch.to_lower() == "a";

match ("a") {
    guard: Debug.println("Found letter 'a'");
    *: Debug.println("Was not the letter 'a'");
}

Additionally, we can use classes and builtin types as our guards as well.

match ("a") {
    String: Debug.println("Value was a string");
    Number: Debug.println("Value was a number");
    *: Debug.println("Did not match a valid type");
}