From 6e140b4797516d9f684c8ae5aeffc43edf71e007 Mon Sep 17 00:00:00 2001
From: Lexus Drumgold <unicornware@flexdevelopment.llc>
Date: Wed, 1 Feb 2023 00:32:28 -0500
Subject: [PATCH] feat(types): `Fn`

Signed-off-by: Lexus Drumgold <unicornware@flexdevelopment.llc>
---
 src/types/__tests__/fn.spec-d.ts | 19 +++++++++++++++++++
 src/types/fn.ts                  | 18 ++++++++++++++++++
 src/types/index.ts               |  1 +
 3 files changed, 38 insertions(+)
 create mode 100644 src/types/__tests__/fn.spec-d.ts
 create mode 100644 src/types/fn.ts

diff --git a/src/types/__tests__/fn.spec-d.ts b/src/types/__tests__/fn.spec-d.ts
new file mode 100644
index 00000000..2ce8943c
--- /dev/null
+++ b/src/types/__tests__/fn.spec-d.ts
@@ -0,0 +1,19 @@
+/**
+ * @file Type Tests - Fn
+ * @module tutils/types/tests/unit-d/Fn
+ */
+
+import type ANY from '../any'
+import type TestSubject from '../fn'
+
+describe('unit-d:types/Fn', () => {
+  it('should be callable with Args', () => {
+    expectTypeOf<TestSubject>().parameters.toEqualTypeOf<ANY[]>()
+    expectTypeOf<TestSubject<[string]>>().parameters.toEqualTypeOf<[string]>()
+  })
+
+  it('should return Ret', () => {
+    expectTypeOf<TestSubject>().returns.toEqualTypeOf<ANY>()
+    expectTypeOf<TestSubject<ANY, string>>().returns.toBeString()
+  })
+})
diff --git a/src/types/fn.ts b/src/types/fn.ts
new file mode 100644
index 00000000..23b5cfd5
--- /dev/null
+++ b/src/types/fn.ts
@@ -0,0 +1,18 @@
+/**
+ * @file Type Definitions - Fn
+ * @module tutils/types/Fn
+ */
+
+import type ANY from './any'
+
+/**
+ * A function.
+ *
+ * @template Args - Arguments type
+ * @template Ret - Return type
+ */
+type Fn<Args extends ANY[] = ANY[], Ret extends ANY = ANY> = (
+  ...args: Args
+) => Ret
+
+export type { Fn as default }
diff --git a/src/types/index.ts b/src/types/index.ts
index f6b52118..0acd26b8 100644
--- a/src/types/index.ts
+++ b/src/types/index.ts
@@ -17,6 +17,7 @@ export type {
   default as ExactOptionalPropertyTypes
 } from './exact-optional-property-types'
 export type { default as FIXME } from './fixme'
+export type { default as Fn } from './fn'
 export type { default as IndexSignature } from './index-signature'
 export type { default as IsTuple } from './is-tuple'
 export type { default as Join } from './join'