types

@sandlada/result (root barrel) and @sandlada/result/types — the discriminated-union contracts every other module builds on.

Scope

• Operates on: the value shapes themselves — IResult, IResultOfT, IOption, AsyncResult, AsyncOption.
• Execution model: none. Every named export is a type; the only runtime export is an empty default object that materializes the entries and their sourcemaps.
• Not here: constructors (factories), transformations (operators, option), async carriers (async-result, promise-result).

API

Result

Export	Description	Source
IResult (type)	Void result union: IResultSuccess | IResultFailure<TError>; TError defaults to unknown.	IResult.ts
IResultSuccess (type)	Success variant without a value (isSuccess: true, isFailure: false).	IResult.ts
IResultFailure (type)	Failure variant carrying error: TError (isSuccess: false, isFailure: true).	IResult.ts
IResultOfT (type)	Value-bearing union: IResultOfTSuccess<TValue> | IResultOfTFailure<TError>; TError defaults to unknown.	IResultOfT.ts
IResultOfTSuccess (type)	Success variant carrying value: TValue (isFailure: false).	IResultOfT.ts
IResultOfTFailure (type)	Failure variant carrying error: TError (isSuccess: false).	IResultOfT.ts

Option

Export	Description	Source
IOption (type)	Optional-value union: IOptionSome<T> | IOptionNone.	Option.ts
IOptionSome (type)	Present value (isSome: true, isNone: false, value: T).	Option.ts
IOptionNone (type)	Absent value (isSome: false, isNone: true).	Option.ts

Async carriers

Export	Description	Source
AsyncResult (type)	Lazy thunk { readonly run: () => Promise<IResultOfT<T, E>> }; E defaults to unknown.	AsyncResult.ts
AsyncOption (type)	Lazy thunk { readonly run: () => Promise<IOption<T>> }.	AsyncOption.ts

Runtime entry marker

Export	Description	Source
default	Empty object. Its only purpose is to make Rolldown materialize the root and /types entries and their sourcemaps; it has no domain behavior.	index.ts

Contract notes

• Results and options are plain objects — no classes, no prototype methods, no sentinels.
• Narrow with the discriminant: isSuccess / isFailure on Results, isSome / isNone on Options. Accessing value on a failure or error on a success is a compile-time error.
• Every property is readonly; values are immutable by contract.
• TError defaults to unknown, not Error: a bare failure carries no usable payload until the caller narrows it.
• The root barrel @sandlada/result and @sandlada/result/types export the same contract set; both are type-focused, and functional runtime values come from subpaths.
• Values survive JSON.stringify unchanged, including both discriminants:

JSON.stringify(ok(42));    // '{"isSuccess":true,"isFailure":false,"value":42}'
JSON.stringify(err('x'));  // '{"isSuccess":false,"isFailure":true,"error":"x"}'
JSON.stringify(ofSome(1)); // '{"isSome":true,"isNone":false,"value":1}'
JSON.stringify(ofNone());  // '{"isSome":false,"isNone":true}'

Design notes

• Pure discriminated unions over classes. Plain objects match TypeScript’s structural type system, serialize trivially, and support property narrowing without instanceof.
• Generic TError over a hardcoded error type. Consumers define their own error contract; the library never converts a domain error into Error on their behalf.
• Type-focused barrel. The root entry exports contracts plus the empty default marker only. Functional runtime values are reachable exclusively through subpaths, which resolves name collisions at the import site and keeps tree-shaking total.

Related

• Every module in src/ depends on these contracts; see the module map in AGENTS.md.
• factories and option are the entry points that create these values.