From e04efc54764b106d428ab495b18d1bf1d9a8c3ea Mon Sep 17 00:00:00 2001
From: Ken Snyder <ken@ken.net>
Date: Wed, 11 Sep 2024 13:36:28 -0700
Subject: [PATCH] feat: added Thenable type and isThenable() type guard

---
 src/runtime/type-guards/isThenable.ts |  8 ++++++++
 src/types/base-types/Thenable.ts      | 12 ++++++++++++
 src/types/base-types/index.ts         |  1 +
 3 files changed, 21 insertions(+)
 create mode 100644 src/runtime/type-guards/isThenable.ts
 create mode 100644 src/types/base-types/Thenable.ts

diff --git a/src/runtime/type-guards/isThenable.ts b/src/runtime/type-guards/isThenable.ts
new file mode 100644
index 00000000..c98aa876
--- /dev/null
+++ b/src/runtime/type-guards/isThenable.ts
@@ -0,0 +1,8 @@
+import { Thenable } from "src/types/index";
+import { isObject } from "./isObject";
+/**
+* type guard which checks whether passed in `val` is a `Thenable` object
+*/
+export const isThenable = (val: unknown): val is Thenable => {
+  return isObject(val) && "then" in val && "catch" in val && typeof val.then === "function";
+}
diff --git a/src/types/base-types/Thenable.ts b/src/types/base-types/Thenable.ts
new file mode 100644
index 00000000..2028ff70
--- /dev/null
+++ b/src/types/base-types/Thenable.ts
@@ -0,0 +1,12 @@
+import { Dictionary } from "./Dictionary";
+
+/**
+ * **Thenable**`<T>`
+ *
+ * An object which resembles a promise and is guarenteed to provide a `.then` and `.catch`
+ * callback hook.
+ */
+export type Thenable<T = unknown> = Dictionary & {
+  then: (cb: T) => void;
+  catch: (err: string) => void;
+}
diff --git a/src/types/base-types/index.ts b/src/types/base-types/index.ts
index ff50eaac..c6fc936e 100644
--- a/src/types/base-types/index.ts
+++ b/src/types/base-types/index.ts
@@ -11,6 +11,7 @@ export * from "./Scalar";
 export * from "./ScalarNotSymbol";
 export * from "./Container";
 export * from "./Tuple";
+export * from "./Thenable";
 export * from "./NumericSign";
 export * from "./Digital";
 export * from "./Indexable";