From 8f52f4ef9f251668a031c7876da1051573e4f864 Mon Sep 17 00:00:00 2001
From: bloodyowl <bloodyowl@icloud.com>
Date: Tue, 20 Feb 2024 14:53:24 +0100
Subject: [PATCH] Prevent Futures from hanging when circular

---
 src/Future.ts       |  3 ++-
 test/Future.test.ts | 10 ++++++++++
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/src/Future.ts b/src/Future.ts
index 16d0bd7..c1e638b 100644
--- a/src/Future.ts
+++ b/src/Future.ts
@@ -101,8 +101,9 @@ export class Future<A> {
   ) {
     const resolver = (value: A) => {
       if (this._state.tag === "Pending") {
-        this._state.resolveCallbacks?.forEach((func) => func(value));
+        const resolveCallbacks = this._state.resolveCallbacks;
         this._state = { tag: "Resolved", value };
+        resolveCallbacks?.forEach((func) => func(value));
       }
     };
 
diff --git a/test/Future.test.ts b/test/Future.test.ts
index dfc8e1d..f5a6712 100644
--- a/test/Future.test.ts
+++ b/test/Future.test.ts
@@ -419,3 +419,13 @@ test("Future isFuture", async () => {
   expect(Future.isFuture([])).toEqual(false);
   expect(Future.isFuture({})).toEqual(false);
 });
+
+test("Future doesn't hang", async () => {
+  const future = Future.make((resolve) => {
+    setTimeout(() => resolve(0), 10);
+  });
+  return future
+    .flatMap(() => Future.value(1))
+    .flatMap(() => future.flatMap(() => Future.value(2)))
+    .tap((value) => expect(value).toEqual(2));
+});