feat(std/results): improve dx in result merging

Author: giveerr

packages/std/src/results/definition.ts

@@ -77,7 +77,11 @@ declare global {
 
     type UnionsToResult<
       U,
-      O = Extract<U, Ok<BlobType, BlobType, BlobType>>,
+      N = Exclude<U, Ok<BlobType, BlobType, BlobType[]> | Err<BlobType, BlobType, BlobType>>,
+      O = Extract<
+        U | (N extends never ? never : Ok<N, never, never>),
+        Ok<BlobType, BlobType, BlobType>
+      >,
       E = Extract<U, Err<BlobType, BlobType, BlobType>>,
     > = O | E extends never
       ? never

packages/std/src/results/utils/fn.ts

@@ -3,21 +3,10 @@ import type { BlobType } from '../../shared'
 import { Err } from './err'
 import { Ok, ok } from './ok'
 
-export const $fn = <
-  A extends BlobType[],
-  R,
-  O extends Exclude<R, Ok<BlobType, BlobType, BlobType[]> | Err<BlobType, BlobType, BlobType>>,
-  C extends Std.ErrorValues = never,
->(
+export const $fn = <A extends BlobType[], R, C extends Std.ErrorValues = never>(
   fn: (...args: A) => R,
   additionalCause?: C
-): ((
-  ...args: A
-) => Std.InjectError<
-  Std.UnionsToResult<R | (O extends never ? never : Ok<O, never, never>)>,
-  never,
-  C extends never ? [] : [C]
->) => {
+): ((...args: A) => Std.InjectError<Std.UnionsToResult<R>, never, C extends never ? [] : [C]>) => {
   return ((...args: A) => {
     const result = fn(...args)
 

packages/std/src/results/utils/try.ts

@@ -7,16 +7,11 @@ import { Ok, ok } from './ok'
 const invalidUsage = resultTags.get('invalid-usage')
 const cause = resultTags.get('try')
 
-export const $try = <
-  R,
-  R2,
-  O extends Exclude<R | R2, Ok<BlobType, BlobType, BlobType[]> | Err<BlobType, BlobType, BlobType>>,
-  C extends Std.ErrorValues = never,
->(
+export const $try = <R, R2, C extends Std.ErrorValues = never>(
   body: () => Generator<R, R2>,
   additionalCause?: C
 ): Std.InjectError<
-  Std.UnionsToResult<R | R2 | (O extends never ? never : Ok<O, never, never>)>,
+  Std.UnionsToResult<R | R2>,
   typeof invalidUsage,
   C extends never ? (typeof cause)[] : (typeof cause | C)[]
 > => {