Ok and Err API
Reference for Result variants, discriminants, payloads, instance methods, and iterator behavior.
Ok<A, E = never>
A successful Result variant. E is phantom: it exists for type composition but is not stored at runtime.
| Member | Type / behavior |
|---|---|
status |
literal "ok" |
value |
A |
isOk() |
returns true and narrows |
isErr() |
returns false and narrows |
map(fn) |
transforms value |
mapError(fn) |
no-op; updates phantom error type |
andThen(fn) |
runs next Result-returning operation |
andThenAsync(fn) |
runs async next operation |
tryRecover(fn) |
no-op; preserves existing success |
tryRecoverAsync(fn) |
async no-op; preserves existing success |
match(handlers) |
runs ok handler |
unwrap() |
returns value |
unwrapOr(fallback) |
returns value |
tap / tapAsync |
observes success |
tapError / tapErrorAsync |
no-op |
tapBoth / tapBothAsync |
runs ok observer |
[Symbol.iterator]() |
returns value to Result.gen without yielding |
Err<T, E>
An error Result variant. T is phantom: it exists for type composition but is not stored at runtime.
| Member | Type / behavior |
|---|---|
status |
literal "error" |
error |
E |
isOk() |
returns false and narrows |
isErr() |
returns true and narrows |
map(fn) |
no-op; updates phantom success type |
mapError(fn) |
transforms error |
andThen(fn) |
no-op; preserves existing error |
andThenAsync(fn) |
async no-op; preserves existing error |
tryRecover(fn) |
runs recovery |
tryRecoverAsync(fn) |
runs async recovery |
match(handlers) |
runs err handler |
unwrap(message?) |
throws Panic with error as cause |
unwrapOr(fallback) |
returns fallback |
tap / tapAsync |
no-op |
tapError / tapErrorAsync |
observes error |
tapBoth / tapBothAsync |
runs err observer |
[Symbol.iterator]() |
yields itself to short-circuit Result.gen |
Construct through Result
const ok = Result.ok(value);
const err = Result.err(error);Ok and Err classes are exported for guards, type declarations, and advanced use, but the constructors on Result communicate intent more clearly.
Callback contract
Instance callbacks are protected. A thrown or rejected callback becomes Panic; it is never silently added to the Result’s typed error union.