Merge pull request #584 from macksal/macksal/ok-void-argument

Allow ok/err/okAsync/errAsync to accept zero arguments when returning void

.changeset/thirty-avocados-explain.md

@@ -0,0 +1,5 @@
+---
+"neverthrow": minor
+---
+
+Allow ok/err/okAsync/errAsync to accept zero arguments when returning void

src/result-async.ts

@@ -228,11 +228,17 @@ export class ResultAsync<T, E> implements PromiseLike<Result<T, E>> {
   }
 }
 
-export const okAsync = <T, E = never>(value: T): ResultAsync<T, E> =>
-  new ResultAsync(Promise.resolve(new Ok<T, E>(value)))
+export function okAsync<T, E = never>(value: T): ResultAsync<T, E>
+export function okAsync<T extends void = void, E = never>(value: void): ResultAsync<void, E>
+export function okAsync<T, E = never>(value: T): ResultAsync<T, E> {
+  return new ResultAsync(Promise.resolve(new Ok<T, E>(value)))
+}
 
-export const errAsync = <T = never, E = unknown>(err: E): ResultAsync<T, E> =>
-  new ResultAsync(Promise.resolve(new Err<T, E>(err)))
+export function errAsync<T = never, E = unknown>(err: E): ResultAsync<T, E>
+export function errAsync<T = never, E extends void = void>(err: void): ResultAsync<T, void>
+export function errAsync<T = never, E = unknown>(err: E): ResultAsync<T, E> {
+  return new ResultAsync(Promise.resolve(new Err<T, E>(err)))
+}
 
 export const fromPromise = ResultAsync.fromPromise
 export const fromSafePromise = ResultAsync.fromSafePromise

src/result.ts

@@ -61,10 +61,15 @@ export namespace Result {
 
 export type Result<T, E> = Ok<T, E> | Err<T, E>
 
-export const ok = <T, E = never>(value: T): Ok<T, E> => new Ok(value)
+export function ok<T, E = never>(value: T): Ok<T, E>
+export function ok<T extends void = void, E = never>(value: void): Ok<void, E>
+export function ok<T, E = never>(value: T): Ok<T, E> {
+  return new Ok(value)
+}
 
 export function err<T = never, E extends string = string>(err: E): Err<T, E>
 export function err<T = never, E = unknown>(err: E): Err<T, E>
+export function err<T = never, E extends void = void>(err: void): Err<T, void>
 export function err<T = never, E = unknown>(err: E): Err<T, E> {
   return new Err(err)
 }