act (property)

Similar to Opt.chain (in other languages called bind or >>=), but supports more functions passed at once (resembles do notation in Haskell). It is used to model a sequence of operations where each operation can fail (can return None).

// does addition when first argument is number
const f1 =
  (x: string | number) => (y: number) => opt(x).narrow(isNumber).map(z => z + y);
// passes only even numbers
const f2 = (x: number): Opt<number> => x % 2 === 0 ? opt(x) : none;

opt(0).act( // Some(0)
  f1(-2), // Some(-2)
  f2, // Some(-2)
  optNegative, // None
); // None

opt(0).act( // Some(0)
  f1(1), // Some(1)
  f2, // None
  optNegative, // won't get called, still None
); // None

opt(3).act( // Some(3)
  f1(1), // Some(4)
  f2, // Some(4)
  optNegative, // Some(4)
); // Some(4)

See

act

Param