feat: add all function to combine multiple Result values

Author: richecr

docs/result/index.md

@@ -416,3 +416,31 @@ console.log(result2); // false
 ```
 
 ---
+
+### `all`
+
+Combines an array of `Result` values into a single `Result`. Returns `Ok` with all values if all are `Ok`, or `Err` with all errors if any are `Err`.
+
+```ts
+import { all, ok, err } from 'holo-fn/result';
+
+// All success case
+const result1 = all([ok(1), ok(2), ok(3)]);
+console.log(result1.unwrapOr([])); // [1, 2, 3]
+
+// Collecting errors
+const result2 = all([err('Name required'), err('Email invalid'), ok(25)]);
+console.log(
+  result2.match({
+    ok: (v) => v,
+    err: (e) => e,
+  })
+); // ['Name required', 'Email invalid']
+
+// Empty array
+const result3 = all([]);
+console.log(result3.unwrapOr([])); // []
+```
+
+---
+

src/result/index.ts

@@ -175,5 +175,24 @@ export const equals =
     return result.equals(other);
   };
 
+export const all = <T, E>(results: Result<T, E>[]): Result<T[], E[]> => {
+  const values: T[] = [];
+  const errors: E[] = [];
+
+  for (const result of results) {
+    if (result.isErr()) {
+      errors.push(result.extract() as E);
+    } else {
+      values.push(result.extract() as T);
+    }
+  }
+
+  if (errors.length > 0) {
+    return new Err<T[], E[]>(errors);
+  }
+
+  return new Ok<T[], E[]>(values);
+};
+
 export const ok = <T, E>(value: T): Result<T, E> => new Ok(value);
 export const err = <T, E>(error: E): Result<T, E> => new Err(error);

tests/result.test.ts

@@ -1,6 +1,7 @@
 import { describe, expect, it } from 'bun:test';
 import { pipe } from 'rambda';
 import {
+  all,
   chain,
   equals,
   Err,
@@ -361,4 +362,34 @@ describe('Result - Curried Helpers', () => {
     const result = pipe(new Err('Error'), equals(new Err('Different Error')));
     expect(result).toBe(false);
   });
+
+  it('all should return Ok with all values when all are Ok', () => {
+    const results = [ok<number, string>(1), ok<number, string>(2), ok<number, string>(3)];
+    const result = all(results);
+    expect(result.isOk()).toBe(true);
+    expect(result.unwrapOr([])).toEqual([1, 2, 3]);
+  });
+
+  it('all should return Err with all errors when any are Err', () => {
+    const results = [ok<number, string>(1), err<number, string>('error1'), err<number, string>('error2')];
+    const result = all(results);
+    expect(result.isErr()).toBe(true);
+    expect(result.match({ ok: (_) => [], err: (e) => e })).toEqual(['error1', 'error2']);
+  });
+
+  it('all should return Ok with empty array for empty input', () => {
+    const result = all<number, string>([]);
+    expect(result.isOk()).toBe(true);
+    expect(result.unwrapOr([])).toEqual([]);
+  });
+
+  it('all should collect all errors from multiple Err', () => {
+    const results = [
+      err<number, string>('Name required'),
+      err<number, string>('Email invalid'),
+      err<number, string>('Age too low'),
+    ];
+    const result = all(results);
+    expect(result.match({ ok: (_) => [], err: (e) => e })).toEqual(['Name required', 'Email invalid', 'Age too low']);
+  });
 });