Function match

  • match<T>(value, patterns): any

  • Pattern matching function for TypeScript.

    Type Parameters

    • T

      The type of the value to be matched.

    Parameters

    • value: T

      The input value to match against patterns.

    • patterns: [((value: T) => boolean), ((value: T) => any)][]

      An array of tuples where:

      • The first element is a predicate function that checks if the pattern applies.
      • The second element is a handler function that executes when the pattern matches.

    Returns any

    • The result of the first matching handler function.

    Throws

    If no pattern matches the input value.

    Example

    const result = match(5, [
      [(n) => n === 10, () => "Exactly ten"],
      [(n) => n > 0, (n) => `Positive: ${n}`],
    ]);
    console.log(result); // Output: "Positive: 5"

    Example

    // Matching against an Option type
    type None = { type: "None" };
    type Some<T> = { type: "Some"; value: T };
    type Option<T> = Some<T> | None;

    const None: None = { type: "None" };
    const Some = <T>(value: T): Some<T> => ({ type: "Some", value });

    const value: Option<number> = Some(15);
    const message = match(value, [
      [(x) => x.type === "Some", (x) => `Some value: ${x.value}`],
      [(x) => x.type === "None", () => "No value"]
    ]);
    console.log(message); // Output: "Some value: 15"

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