Merge branch 'master' into schniz/remove-maintainer-callout

supermacro · Aug 5, 2024 · 8aac6ae · 8aac6ae
2 parents 036b8ad + ced9108
commit 8aac6ae
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diff --git a/.changeset/mean-eagles-develop.md b/.changeset/mean-eagles-develop.md
@@ -0,0 +1,5 @@
+---
+"neverthrow": patch
+---
+
+fix: change type definitions to make inferring types of safeTry more strict
diff --git a/src/result.ts b/src/result.ts
@@ -77,6 +77,16 @@ export const err = <T = never, E = unknown>(err: E): Err<T, E> => new Err(err)
  * @returns The first occurence of either an yielded Err or a returned Result.
  */
 export function safeTry<T, E>(body: () => Generator<Err<never, E>, Result<T, E>>): Result<T, E>
+export function safeTry<
+  YieldErr extends Err<never, unknown>,
+  GeneratorReturnResult extends Result<unknown, unknown>
+>(
+  body: () => Generator<YieldErr, GeneratorReturnResult>,
+): Result<
+  InferOkTypes<GeneratorReturnResult>,
+  InferErrTypes<YieldErr> | InferErrTypes<GeneratorReturnResult>
+>
+
 /**
  * Evaluates the given generator to a Result returned or an Err yielded from it,
  * whichever comes first.
@@ -95,6 +105,17 @@ export function safeTry<T, E>(body: () => Generator<Err<never, E>, Result<T, E>>
 export function safeTry<T, E>(
   body: () => AsyncGenerator<Err<never, E>, Result<T, E>>,
 ): Promise<Result<T, E>>
+export function safeTry<
+  YieldErr extends Err<never, unknown>,
+  GeneratorReturnResult extends Result<unknown, unknown>
+>(
+  body: () => AsyncGenerator<YieldErr, GeneratorReturnResult>,
+): Promise<
+  Result<
+    InferOkTypes<GeneratorReturnResult>,
+    InferErrTypes<YieldErr> | InferErrTypes<GeneratorReturnResult>
+  >
+>
 export function safeTry<T, E>(
   body:
     | (() => Generator<Err<never, E>, Result<T, E>>)

diff --git a/tests/typecheck-tests.ts b/tests/typecheck-tests.ts
@@ -13,7 +13,7 @@ import {
   Result,
   ResultAsync,
 } from '../src'
-import { Transpose } from '../src/result'
+import { safeTry, Transpose } from '../src/result'
 import { type N, Test } from 'ts-toolbelt'
 
 type CreateTuple<L, V = string> =
@@ -1961,6 +1961,158 @@ type CreateTuple<L, V = string> =
 });
 
 (function describe(_ = 'Utility types') {
+  (function describe(_ = 'safeTry') {
+    (function describe(_ = 'sync generator') {
+      (function it(_ = 'should correctly infer the result type when generator returns Ok') {
+        interface ReturnMyError {
+          name: 'ReturnMyError'
+        }
+
+        type Expectation = Result<string, ReturnMyError>
+
+        const result = safeTry(function *() {
+          return ok<string, ReturnMyError>('string');
+        })
+        Test.checks([
+          Test.check<typeof result, Expectation, Test.Pass>(),
+        ])
+      });
+
+      (function it(_ = 'should correctly infer the result type when generator returns Err') {
+        interface ReturnMyError {
+          name: 'ReturnMyError';
+        }
+
+        type Expectation = Result<string, ReturnMyError>
+
+        const result = safeTry(function *() {
+          return err<string, ReturnMyError>({ name: 'ReturnMyError' });
+        })
+        Test.checks([
+          Test.check<typeof result, Expectation, Test.Pass>(),
+        ])
+      });
+
+      (function it(_ = 'infers the value type when calling "yield*"') {
+        interface YieldMyError {
+          name: 'YieldMyError';
+        }
+        interface ReturnMyError {
+          name: 'ReturnMyError';
+        }
+
+        safeTry(function *() {
+          type Expectation = number
+
+          const unwrapped = yield* ok<number, YieldMyError>(123).safeUnwrap();
+          Test.checks([
+            Test.check<typeof unwrapped, Expectation, Test.Pass>(),
+          ])
+
+          return ok<string, ReturnMyError>('string');
+        })
+      });
+
+      (function it(_ = 'should correctly infer the result type with multiple "yield*"') {
+        interface FirstYieldMyError {
+          name: 'FirstYieldMyError';
+        }
+        interface SecondYieldMyError {
+          name: 'SecondYieldMyError';
+        }
+        interface ReturnMyError {
+          name: 'ReturnMyError';
+        }
+
+        type Expectation = Result<string, FirstYieldMyError | SecondYieldMyError | ReturnMyError>
+
+        const result = safeTry(function *() {
+          yield* ok<number, FirstYieldMyError>(123).safeUnwrap();
+          yield* err<never, SecondYieldMyError>({ name: 'SecondYieldMyError' }).safeUnwrap();
+          return ok<string, ReturnMyError>('string');
+        })
+        Test.checks([
+          Test.check<typeof result, Expectation, Test.Pass>(),
+        ])
+      });
+    });
+
+    (function describe(_ = 'async generator') {
+      (function it(_ = 'should correctly infer the result type when generator returns OkAsync') {
+        interface ReturnMyError {
+          name: 'ReturnMyError'
+        }
+
+        type Expectation = Promise<Result<string, ReturnMyError>>
+
+        const result = safeTry(async function *() {
+          return okAsync<string, ReturnMyError>('string');
+        })
+        Test.checks([
+          Test.check<typeof result, Expectation, Test.Pass>(),
+        ])
+      });
+
+      (function it(_ = 'should correctly infer the result type when generator returns ErrAsync') {
+        interface ReturnMyError {
+          name: 'ReturnMyError';
+        }
+
+        type Expectation = Promise<Result<string, ReturnMyError>>
+
+        const result = safeTry(async function *() {
+          return errAsync<string, ReturnMyError>({ name: 'ReturnMyError' });
+        })
+        Test.checks([
+          Test.check<typeof result, Expectation, Test.Pass>(),
+        ])
+      });
+
+      (function it(_ = 'infers the value type when calling "yield*"') {
+        interface YieldMyError {
+          name: 'YieldMyError';
+        }
+        interface ReturnMyError {
+          name: 'ReturnMyError';
+        }
+
+        safeTry(async function *() {
+          type Expectation = number
+
+          const unwrapped = yield* okAsync<number, YieldMyError>(123).safeUnwrap();
+          Test.checks([
+            Test.check<typeof unwrapped, Expectation, Test.Pass>(),
+          ])
+
+          return ok<string, ReturnMyError>('string');
+        })
+      });
+
+      (function it(_ = 'should correctly infer the result type with multiple "yield*"') {
+        interface FirstYieldMyError {
+          name: 'FirstYieldMyError';
+        }
+        interface SecondYieldMyError {
+          name: 'SecondYieldMyError';
+        }
+        interface ReturnMyError {
+          name: 'ReturnMyError';
+        }
+
+        type Expectation = Promise<Result<string, FirstYieldMyError | SecondYieldMyError | ReturnMyError>>
+
+        const result = safeTry(async function *() {
+          yield* okAsync<number, FirstYieldMyError>(123).safeUnwrap();
+          yield* errAsync<never, SecondYieldMyError>({ name: 'SecondYieldMyError' }).safeUnwrap();
+          return okAsync<string, ReturnMyError>('string');
+        })
+        Test.checks([
+          Test.check<typeof result, Expectation, Test.Pass>(),
+        ])
+      });
+    });
+  });
+
   (function describe(_ = 'Transpose') {
     (function it(_ = 'should transpose an array') {
       const input: [