From a23edf36051f2147de6979ab5f185a86b4753e64 Mon Sep 17 00:00:00 2001
From: themodernhakr <ehrumsey@gmail.com>
Date: Thu, 12 Jun 2025 00:37:01 -0500
Subject: [PATCH] Fix error typing in AsyncDoEither

---
 package.json  |  2 +-
 src/either.ts | 11 +++++------
 2 files changed, 6 insertions(+), 7 deletions(-)

diff --git a/package.json b/package.json
index 2bc54ec..fcaaf2e 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "fp-lib",
-  "version": "1.0.2",
+  "version": "1.0.3",
   "description": "Zero-dependency functional programming library optimized for Bun",
   "main": "dist/index.js",
   "module": "dist/index.js",
diff --git a/src/either.ts b/src/either.ts
index 3d05cc7..fcba02e 100644
--- a/src/either.ts
+++ b/src/either.ts
@@ -216,7 +216,6 @@ export class AsyncDoEither<T extends Record<string, unknown>, E> {
     f: (scope: T) => Either<A, E> | Promise<Either<A, E>>,
   ): AsyncDoEither<T & Record<K, A>, E> {
     const newPromise = this.promise.then(async (currentEither) => {
-      // Propagate Left case as is
       if (currentEither._tag === 'Left') {
         return currentEither as Either<T & Record<K, A>, E>
       }
@@ -225,18 +224,15 @@ export class AsyncDoEither<T extends Record<string, unknown>, E> {
       try {
         const nextEither = await f(scope)
 
-        // Propagate Left from bound computation
         if (nextEither._tag === 'Left') {
           return nextEither as Either<T & Record<K, A>, E>
         }
 
-        // Extend scope with new value
         return right({
           ...scope,
           [key]: nextEither.right,
         }) as Either<T & Record<K, A>, E>
       } catch (err) {
-        // Handle unexpected exceptions
         return left(err as E)
       }
     })
@@ -255,7 +251,7 @@ export class AsyncDoEither<T extends Record<string, unknown>, E> {
       if (either._tag === 'Left') {
         return either as Either<B, E>
       }
-      return right(f(either.right))
+      return right(f(either.right)) as Either<B, E>
     })
   }
 
@@ -308,9 +304,12 @@ export class AsyncDoEither<T extends Record<string, unknown>, E> {
 
   /**
    * Starts a new AsyncDoEither chain with an empty scope
+   * @typeParam E - The error type
    * @returns A new AsyncDoEither instance with an empty scope
    */
   static start<E>(): AsyncDoEither<{}, E> {
-    return new AsyncDoEither(Promise.resolve(right({})))
+    // Fix: Create a Right value with explicit error type casting
+    const initial: Either<{}, E> = right({}) as Either<{}, E>
+    return new AsyncDoEither(Promise.resolve(initial))
   }
 }