feat: add ResultValue and ResultError helper types

src/_internals/utils.ts

@@ -21,12 +21,6 @@ export type ExtractErrAsyncTypes<T extends readonly ResultAsync<unknown, unknown
   [idx in keyof T]: T[idx] extends ResultAsync<unknown, infer E> ? E : never
 }
 
-export type InferOkTypes<R> = R extends Result<infer T, unknown> ? T : never
-export type InferErrTypes<R> = R extends Result<unknown, infer E> ? E : never
-
-export type InferAsyncOkTypes<R> = R extends ResultAsync<infer T, unknown> ? T : never
-export type InferAsyncErrTypes<R> = R extends ResultAsync<unknown, infer E> ? E : never
-
 /**
  * Short circuits on the FIRST Err value that we find
  */

src/index.ts

@@ -1,9 +1,21 @@
-export { Result, ok, Ok, err, Err, fromThrowable, safeTry } from './result'
+export {
+  Err,
+  Ok,
+  Result,
+  err,
+  fromThrowable,
+  ok,
+  safeTry,
+  InferErrTypes,
+  InferOkTypes,
+} from './result'
 export {
   ResultAsync,
-  okAsync,
   errAsync,
   fromAsyncThrowable,
   fromPromise,
   fromSafePromise,
+  okAsync,
+  InferAsyncErrTypes,
+  InferAsyncOkTypes,
 } from './result-async'

src/result-async.ts

@@ -5,6 +5,8 @@ import type {
   IsLiteralArray,
   MemberListOf,
   MembersToUnion,
+  InferErrTypes,
+  InferOkTypes,
 } from './result'
 
 import { Err, Ok, Result } from './'
@@ -13,12 +15,22 @@ import {
   combineResultAsyncListWithAllErrors,
   ExtractErrAsyncTypes,
   ExtractOkAsyncTypes,
-  InferAsyncErrTypes,
-  InferAsyncOkTypes,
-  InferErrTypes,
-  InferOkTypes,
 } from './_internals/utils'
 
+/**
+ * Extract the ok type from a `ResultAsync` type
+ * @example
+ * type OkType = InferAsyncOkTypes<ResultAsync<number, string>> // number
+ */
+export type InferAsyncOkTypes<R> = R extends ResultAsync<infer T, unknown> ? T : never
+
+/**
+ * Extract the error type from a `ResultAsync` type
+ * @example
+ * type ErrType = InferAsyncErrTypes<ResultAsync<number, string>> // string
+ */
+export type InferAsyncErrTypes<R> = R extends ResultAsync<unknown, infer E> ? E : never
+
 export class ResultAsync<T, E> implements PromiseLike<Result<T, E>> {
   private _promise: Promise<Result<T, E>>
 

src/result.ts

@@ -1,15 +1,26 @@
-import { errAsync, ResultAsync } from './'
+import { errAsync, ResultAsync, InferAsyncErrTypes } from './'
 import { createNeverThrowError, ErrorConfig } from './_internals/error'
 import {
   combineResultList,
   combineResultListWithAllErrors,
   ExtractErrTypes,
   ExtractOkTypes,
-  InferAsyncErrTypes,
-  InferErrTypes,
-  InferOkTypes,
 } from './_internals/utils'
 
+/**
+ * Infers the ok types from a Result
+ * @example
+ * type OkType = InferOkTypes<Result<number, string>> // number
+ */
+export type InferOkTypes<R> = R extends Result<infer T, unknown> ? T : never
+
+/**
+ * Infers the error types from a Result
+ * @example
+ * type ErrType = InferErrTypes<Result<number, string>> // string
+ */
+export type InferErrTypes<R> = R extends Result<unknown, infer E> ? E : never
+
 // eslint-disable-next-line @typescript-eslint/no-namespace
 export namespace Result {
   /**