Guard

The Guard primitive provides a mechanism to encapsulate a value of type T and offers methods to handle scenarios where the value may be undefined. It allows retrieving a default value or throwing an error when the Guard value is undefined.

APIs

The Guard<T> primitive provides methods to handle potential undefined values.

In these APIs' examples we will use the guardAsync utility function that always repond with a Promise of Guard.

Returns the guarded value or the default value if the guarded value is undefined.

Example

// if couldReturnUndefined() returns undefined we provide a default value.
const username = await guardAsync(couldReturnUndefined()).or("John Doe");

Returns the guarded value if it is not undefined, otherwise throws an error.

Example

// wrap the guardAsync that could throw inside a tryAsync and handle the possible error.
const usernameMaybe = await tryAsync(
  guardAsync(couldReturnUndefined())._throws()
);
if (usernameMaybe.isErr()) {
  const err = usernameMaybe.getErr();
  // handle the error
}
const username = usernameMaybe.unwrap();