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Combine results

Short-circuit on first failure — andThen​

Chain operations where each step depends on the previous success.

const response = await readConfig(path)
	.andThen(parseConfig)
	.andThen(validateConfig);

Each callback receives the predecessor's T and must return a Result. The first Err short-circuits the chain.

Take the first — and, or​

and(other) returns other if this is Ok, otherwise returns this. Useful when you only care that both succeed but want to discard the first value.

const pair = authenticate().and(loadProfile);

or(other) is the inverse: returns this if Ok, otherwise other.

const source = readPrimary().or(readSecondary);

Flatten a nested Result — flatten​

When a transformation produces Result<Result<T, E2>, E1>, call .flatten() to collapse one level.

const doubled: Result<Result<number, E2>, E1> = /* ... */;
const single: Result<number, E1 | E2> = doubled.flatten();

andThen(identity) is equivalent to .flatten().

See also​