fix type

lib/utils.ts

@@ -1,6 +1,6 @@
 import { None, Option, Some } from "./option";
 import { Err, Ok, Result } from "./result";
-import { AsyncTask, SyncTask, Task } from "./task";
+import { Task } from "./task";
 
 export function identity<A>(a: A): A {
   return a;
@@ -14,18 +14,12 @@ export function isOption<A>(value: unknown): value is Option<A> {
   return value instanceof Some || value instanceof None;
 }
 
-export function isTask<E, A>(
-  value: unknown
-): value is AsyncTask<E, A> | SyncTask<E, A> {
+export function isTask<E, A>(value: unknown): value is Task<E, A> {
   return value instanceof Task;
 }
 
 export function isMonad(value: unknown): value is Monad<unknown, unknown> {
   return isOption(value) || isResult(value) || isTask(value);
 }
 
-export type Monad<E, A> =
-  | Option<A>
-  | Result<E, A>
-  | AsyncTask<E, A>
-  | SyncTask<E, A>;
+export type Monad<E, A> = Option<A> | Result<E, A> | Task<E, A>;